Separations doi: 10.3390/separations11030088
Authors: Yinpeng Wang Yumei Li Yan Ding Xinxin Du Jingbo Zhu
Chemical composition is a critical factor for determining the efficacy of any traditional Chinese medicine (TCM) and can be used as an indicator of commercial quality. To develop a new strategy for discovering potential quality markers (Q-markers) of TCM by integrating ultra-performance liquid chromatography-Q-extractive orbitrap/mass spectrometry (UPLC-Q-Extractive Orbitrap/MS), chemometric analysis, and network pharmacology, using Schisandra chinensis (Turcz.) Baill. (S. chinensis) as an example. The chemical profiling of S. chinensis was performed using UPLC-Q-Extractive Orbitrap/MS, followed by identification of hepatoprotective Q-markers through a comprehensive understanding of chemometric analysis and virtual target prediction of network pharmacology. Six compounds were considered potent candidates for Q-markers, which were identified as schisandrol A (6), angeloylgomisin H (10), schisantherin A (17), schisantherin B (18), schisandrin A (23), and schisandrin C (26). All Q-markers exhibited significant hepatoprotective activity, as evidenced by in vitro experiments. Subsequently, a method for simultaneous quantification was established and employed to analyse seven batches of S. chinensis. Therefore, the integrated approach of UPLC-Q-Extractive Orbitrap/MS, chemometrics, and network pharmacology proved to be an effective strategy for the discovery of Q-markers that can assist in assessing the overall chemical consistency of samples and provide a basis for quality evaluation of the material basis of S. chinensis.
]]>Separations doi: 10.3390/separations11030087
Authors: Hanwen Yuan Wei Su Ling Liang Qingling Xie Mengying Lyu Huanghe Yu Bin Li Wei Wang
Xuetong, the dried stem of Kadsura heteroclita (Roxb.) Craib, is a traditional Tujia medicine extensively used to treat rheumatoid arthritis (RA). All traditional Chinese medicines (TCMs) necessitate a processing stage called “Paozhi” before clinical application. However, there is a dearth of research concerning the processing methods employed for Xuetong. To investigate the impact of vinegar and wine processing on the chemical constituents of Xuetong, this study devised a targeted offline two-dimensional (2D) high-performance liquid chromatography (HPLC) and ultra-high-performance liquid chromatography-orbitrap mass spectrometry (UHPLC-orbitrap-MS) method. By incorporating various MS data-processing techniques, such as molecular networking technology, fragment-ion similarity searching (FISh), online and offline database matching, and fragmentation pattern analysis, a total of 158 components were identified in Xuetong. Among them, 14 were verified by comparison with the reference standards. Notably, aside from triterpenoids and lignans, catechin derivatives were found to be the predominant constituents of Xuetong, and their levels exhibited a significant decrease following processing. This method significantly improved peak capacity and resolution, overcoming the limitations of 1D LC in simultaneously analyzing highly polar catechin derivatives and less polar triterpenoids and lignans. Moreover, the developed method shows promise for Xuetong’s quality control.
]]>Separations doi: 10.3390/separations11030086
Authors: Meina Liang Zimeng Wu Haiyan Cao Kun Dong Shaoyuan Bai Dunqiu Wang
Mg/Fe layered bimetallic oxide mulberry rod biochar composites (MFBCs) were prepared from mulberry rods and characterized using electron microscopy scanning (SEM), X-ray diffraction (XRD), Fourier infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). We investigated the adsorption properties of MFBCs for phosphorus, which was recovered via crystallization using calcium chloride as a precipitant. According to the findings, the MFBC is a layered bimetallic oxide with a specific surface area of 70.93 m2·g−1. Its point of zero charge values, or pHzpc, was 7.66. The removal of phosphorus usingMFBCs gradually decreased with increasing pH, and the optimum pH for phosphorus removal was 4.0. The maximum phosphorus adsorption by MFBCs at 298 K was 29.682 mg·g−1 for MFBCs. The adsorption process of phosphorus onto MFBCs is a heat absorption process, and the adsorption isothermal data of phosphorus onto MFBCs fit with the Langmuir adsorption isothermal model. Phosphorus recovery is achieved when calcium chloride is added to the phosphate-enriched desorption solution at a Ca/P molar ratio of 2.2. The phosphorus product obtained from this process is very pure hydroxyphospapatite. The recovery rate of phosphorus in the desorption solution is 99.64%.
]]>Separations doi: 10.3390/separations11030085
Authors: A. Celeste Medrano Ariela Cantu Edgar O. Aviles-Rosa Nathaniel J. Hall Michele N. Maughan Jenna D. Gadberry Paola A. Prada-Tiedemann
This study focused on evaluating human body odor volatiles using a chamber approach. Ten participants were asked to sit inside the chamber for 1 h, while using SPME as the extraction technique for vapor sampling. A total of 105 compounds were detected across participants, with nonanal having the highest frequency. PCA statistical analysis depicted tighter clustering in female whole-body odor profiles when compared to males, thus corroborating gender odor differences. Concurrently, various biospecimens (hand, axillary, breath) from the same participants allowed for a comparison between whole-body and individual biospecimen odor signatures. When comparing whole-body sampling and distinctive biospecimens, nonanal and decanal were the only odor volatiles shared. Statistical clustering depicted higher similarity within the odor profiles of individual biospecimens compared to odor profiles of the whole body, indicating distinctiveness of the odor chemical landscape as a function of sampling region. Overall, this study demonstrated that SPME-GC/MS methodology was successful in the extraction, detection, and identification of previously reported human scent volatiles when employing the human chamber for whole-body sampling. Our presented testing paradigm allows for a direct comparison of odor volatiles across the full body and specific body locations that allows odor markers to be furthered exploited for diagnostic and biological detection contexts.
]]>Separations doi: 10.3390/separations11030084
Authors: Hasaruwani S. Kiridena Sharmila I. Thenuwara Manjula M. Kandage Norman Peiffer Michal Marszewski Dragan Isailovic
Microcystins (MCs) and nodularins (NODs) are cyanotoxins that can be found in water bodies during cyanobacterial harmful algal blooms (cyanoHABs). Consumption of water contaminated with cyanotoxins leads to health risks for humans and animals. Herein, corncob-based biochar and activated carbon (AC) were initially investigated for the sorption of six common MC congeners (MC-RR, MC-YR, MC-LR, MC-LA, MC-LW, and MC-LF) and nodularin-R (NOD-R) from spiked water. Biochar was prepared by refluxing commercial corncob with HCl and heating it to 250, 300, or 350 °C. AC was prepared by chemical activation of corncob with H3PO4 at 500 °C under a nitrogen atmosphere. Low-temperature nitrogen adsorption measurements confirmed that H3PO4-AC has a higher specific surface area (≈1100 m2/g) and total pore volume (≈0.75 cm3/g) than biochar and commercial AC. H3PO4-AC showed the maximum efficacy, among all corncob-based sorbents, to remove MCs and NOD-R from water as confirmed by experiments that involved sample analyses by ultrahigh-pressure liquid chromatography-mass spectrometry (UHPLC-MS). The effect of natural organic matter (NOM) on the adsorption of MCs was checked by incubating sorbents with Lake Erie water collected during cyanoHABs from 2020 to 2022. The total concentration (extracellular and intracellular) of studied MC congeners ranged from 1.37 µg/L to 438.51 µg/L and 50 mg of H3PO4-AC completely removed them from 3 mL of lake water. The effect of water pH on cyanotoxin adsorption was studied at pH values of 5.5, 7.0, and 8.5 at both a lower (10 μg/L each) and a higher (50 μg/L each) toxin concentration. Removal was influenced by solution pH at both concentrations when using biochar, while only at higher toxin concentration when using H3PO4-AC. At higher MC and NOD-R concentrations, competitive adsorption was prominent, and overall, the adsorption increased at acidic pH (5.5). The study results suggest that processed corncobs can remove a significant amount of MCs and NOD-R from water, and the measured sorption capacity of H3PO4-AC was ~20 mg of MC-LR and NOD-R per g of this sorbent.
]]>Separations doi: 10.3390/separations11030083
Authors: Sami El Deeb Khalid Abdelsamad Maria Kristina Parr
A sustainable reversed-phase chromatographic method has been developed and validated for the simultaneous determination of three active pharmaceutical ingredients, dorzolamide, brinzolamide, and timolol, used to treat glaucoma. The eco-friendly solvent isopropanol has been used as an organic mobile phase constituent. According to the Hansen space green solvent selection tool, isopropanol has a G score of 6.5, comparable to ethanol, which has a G score of 6.6. The mobile phase consists of isopropanol: aqueous sodium acetate buffer (0.1 M, pH 4.25) in the ratio of 10:90 (v/v). The flow rate was maintained at 1 mL/min. Dorzolamide and brinzolamide were detected at 254 nm, and timolol was detected at 295 nm. A high-purity silica with a polymeric C18 modification column (150 × 4.6 mm, 5 µm particle size) was used for this separation. The three compounds were eluted within 8 min. The method was validated according to ICH guidelines. The calibration curves were linear in the range of 20–70 µg/mL, 40–140 µg/mL, and 20–70 µg/mL for dorzolamide, brinzolamide, and timolol, respectively. The LODs were found to be 1.61 µg/mL, 1.60 µg/mL, and 3.16 µg/mL for dorzolamide, brinzolamide, and timolol, respectively. Good accuracy and precision were obtained for the three compounds. The greenness and whiteness of the method were indicated using the AGREE, ChlorTox, and RGB12 tools.
]]>Separations doi: 10.3390/separations11030082
Authors: Bohyun Shin Hyung-seung Kim Ji-Youn Lee Sumin Seo Cho Hee Jeong Eunbin Bae Jiyu Kim Hyojeong Lee Donghee Lee Dong-Kyu Lee Sang Beom Han
Pralidoxime chloride, a highly hydrophilic antidote, cannot be effectively separated by reverse-phase high-performance liquid chromatography (RP-HPLC), unless the mobile-phase composition is varied. However, the use of ion-pairing reagents for pralidoxime separation is hindered by the persistent contamination of the stationary phase or chromatography system inside the HPLC system. Thus, this study aimed to develop a simple, rapid, and robust method based on RP-HPLC to determine pralidoxime chloride in antidote autoinjectors using a chaotropic salt as the mobile-phase additive. The use of UV detection at 270 nm allowed for the simultaneous detection of pralidoxime chloride and the internal standard, pyridine-2-aldoxime. The addition of chaotropic salts (NaPF6, NaBF4, and NaClO4) and an ionic liquid ([EMIM]PF6) increased the retention time of pralidoxime chloride. Among them, NaPF6 exhibited the highest capacity factor in the reverse-phase C18 column. Increasing the salt concentration increased the capacity factor and the number of theoretical plates. Analytical method validation was performed to assess the linearity, accuracy, precision, recovery, and repeatability, according to the Ministry of Food and Drug Safety guidelines. Additionally, this newly developed method exhibits an adequate separation capability, making it a potential substitute for the current method employed in the United States/Korean Pharmacopoeia, and it ensures the necessary durability to maintain the robustness and reliability of the analytical system.
]]>Separations doi: 10.3390/separations11030081
Authors: Alena Stupar Senka Vidović Jelena Vladić Tanja Radusin Aleksandra Mišan
Utilizing natural plant extracts as food additives represents a promising strategy for enhancing the quality, nutritional value, and safety of food products, benefiting both consumers and the environment. Therefore, the primary objective of this study was to develop an environmentally sustainable process for the production of solid powder derived from Allium ursinum liquid extract, with the intent of utilizing it as a natural food additive. To address the challenge of instability and enhance the solubility of bioactive compounds in A. ursinum extracts obtained through subcritical water extraction, this study employed the spray drying process. Notably, the results demonstrated the remarkable efficiency of the spray drying process, with maltodextrin as a carrier, yielding uniformly encapsulated particles with an average size of approximately 4 µm, spherical shape with smooth, intact surfaces. The most optimal conditions for achieving the highest content of total phenolics (23.10 mg GAE/g) and total flavonoids (4.92 mg CE/g) in the A. ursinum extract were identified, involving an inlet temperature of 120 °C and an 80% maltodextrin concentration. The encapsulated powders showed excellent stability, with minimal loss of total phenolics (12.64%) and total flavonoids (10.52%) after three months of storage. Physicochemical analysis confirmed the successful preservation of bioactive compounds through microencapsulation using maltodextrin, suggesting its potential for application in innovative food or pharmaceutical products.
]]>Separations doi: 10.3390/separations11030080
Authors: Shuwen Xue Yunhu Hu Keji Wan Zhenyong Miao
Water pollution poses a global threat to human health, particularly in terms of ensuring a safe supply of drinking water. The accumulation of heavy metals from various water sources is increasing, driving the search for effective and environmentally friendly approaches and materials for metal removal. This review investigates the selective adsorption of Pb2+ by humic acid (HA) in a multi-metal coexistence solution. The focus is on discussing approaches to the structural identification of HA, highlighting that separation techniques are an effective method to reduce its heterogeneity. Starting from the key structural units of HA, the study reveals the interaction between HA and heavy metals. Approaches to enhance Pb2+ selective adsorption are explored, proposing that introducing activating groups, Ca ion exchange, and optimizing pore structures are effective approaches for improving lead ion selective adsorption. Ca2+ activation is suggested as a future research direction for lead-selective adsorption. Additionally, attaining lead selective adsorption through pH regulation’s significance is emphasized. This research contributes to a fundamental understanding of HA’s role as a selective lead adsorbent while offering practical implications for developing environmentally friendly adsorbent materials. The results aim to advance knowledge in environmental science and water treatment.
]]>Separations doi: 10.3390/separations11030079
Authors: Jong Gu Kim Byong Chol Bai
This study investigates lyocell-based activated carbon fibers (ACFs) for their suitability in adsorbing and electrochemically detecting toxic HCl gas. ACFs were prepared via steam activation, varying temperature (800–900 °C) and time (40–240 min) to assess their adsorption and sensing capabilities. The adjustment of activation temperature and reaction time aimed to regulate the uniformity of the pore structure and pore size of the active reaction area, as well as the number of reaction sites in the ACFs. Optimal ACFs were achieved at 900 °C for 50 min, exhibiting the highest specific surface area (1403 m2/g) and total pore volume (0.66 cm3/g). Longer reaction times resulted in pore formation and disorder, reducing mechanical strength. The ACFs prepared under optimal conditions demonstrated a rapid increase in resistance during sensor measurement, indicating a significant sensitivity to HCl gas. These findings suggest the potential of ACFs for efficient HCl gas adsorption (1626.20 mg/g) and highlight the importance of activation parameters in tailoring their properties for practical applications.
]]>Separations doi: 10.3390/separations11030078
Authors: Beatrice Arwenyo Prashan M. Rodrigo Olalekan A. Olabode Hashani P. Abeysinghe Jessie N. Tisdale Rose C. Azuba Todd E. Mlsna
Copper is a non-biodegradable heavy metal, and high levels in water bodies cause serious environmental and health issues. Douglas fir biochar has a higher number of carboxylic, phenolic, and lactonic groups, which provide suitable active sites for copper removal. Douglas fir biochar (BC) was modified using 20% solutions of KOH (KOH/BC), H2SO4, (H2SO4/BC), and Na2CO3 (Na2CO3/BC). All materials were characterized using SEM, SEM-EDS, FTIR, TGA, XRD, BET, and elemental analysis. These modifications were done to compare the activations of those sites by measuring copper removal efficiencies. KOH/BC, H2SO4/BC, and Na2CO3/BC materials gave surface areas of 389.3, 326.7, and 367.9 m2 g−1, respectively, compared with pristine biochar with a surface area of 578.9 m2 g−1. The maximum Langmuir adsorption capacities for Na2CO3/BC, KOH/BC, BC, and H2SO4/BC were 24.79, 18.31, 17.38, and 9.17 mg g−1, respectively. All three modifications gave faster kinetics at 2 mg/L initial copper concentrations (pH 5) compared with pristine BC. The copper removal efficiency was demonstrated in four different spiked real water matrices. The copper removals of all four water matrices were above 90% at 2 mg/L initial concentration with a 2 g/L biochar dosage. The competitive effects of Pb2+, Zn2+, Cd2+, and Mg2+ were studied at equimolar concentrations of Cu2+ and competitive ions for all four materials.
]]>Separations doi: 10.3390/separations11030077
Authors: Da Li Zhan Yang Kun Wang Lan Zhang Linglong Shi Abdul Qadeer Jiao Dong Haoyu Ren
Nickel titanate (NiTiO3) semiconductors and graphitic carbon nitride (g-C3N4) have attracted great attention as photocatalysts in the degradation of environmental pollutants because of their visible-light-driven activity. But the utilizations of both semiconductors are limited by their low specific surface area. In this study, a nano-NiTiO3/g-C3N4 photocatalyst was successfully synthesized by optimizing the preparation method of photocatalyst precursors. Compared with the bulk g-C3N4 and bulk NiTiO3/g-C3N4 composite photocatalysts, the nano-NiTiO3/g-C3N4 composite catalyst displayed a larger specific surface area, a more abundant pore size structure, and superior carrier separation capabilities. According to the pseudo-first-order, the degradation rate of MB was more than 2.5–19.7 times higher than that of previous studies. The superoxide radicals (·O2−) and holes (h+) played significant roles in the photocatalytic reaction of MB. This study provides a new idea for the synthesis of photocatalysts and the improvement in photocatalytic performance.
]]>Separations doi: 10.3390/separations11030076
Authors: Kou-Toung Chung Ching-Lung Lin Wu-Chang Chuang Ming-Chung Lee Li-Wen Chen Chung-Hsin Wu
Bat feces have been reported in traditional Chinese medicine (TCM) books to have the effect of reducing fever and improving eyesight, but the mechanism of vision improvement still needs further research. To this end, we used 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and liquid chromatography/tandem mass spectrometry (LC/MS/MS) to analyze the antioxidant capacity of and the types of vitamins in bat feces. We hoped to screen the pharmacological components of bat feces and to explain the role that these components may play in treating visual deterioration. Our results found that bat feces had a good antioxidant capacity and mainly contained vitamins B1 (thiamine), B2 (riboflavin), B3 (nicotinamide), B3 (nicotinic acid), and B5 (pantothenic acid). Although these vitamins may help to maintain the health of the optic nerve and cornea, the vitamin content of bat feces is low, but the heavy metal content is high, as shown using inductively coupled plasma–mass spectrometry (ICP-MS) analysis. Therefore, we suggest that the use of bat feces as TCM to improve vision should be strictly restricted.
]]>Separations doi: 10.3390/separations11030075
Authors: Jianjun Zhao Junqing Sun Kefeng Zhang Shan Wang Wande Ding Zhengping Li
A liposome vesicle is an ideal carrier for carbon nanotubes (CNTs) serving as the water channel that allows for the fast transport of water molecules, thus enhancing membrane permeability. However, a low quantity of CNTs inserted into the liposome vesicle is an important factor that limits the further improvement of the membrane flux. In the present study, a positively charged lipid, (2,3-dioleoyloxy-propyl)-trimethylammonium-chloride (DOTAP), was introduced to 1,2-dioleoyl-sn-glycero-3-phosphoethanolamineon (DOPE) liposome vesicles to tailor the vesicle charge so as to evaluate the effect of positively charged DOTAP on the insertion of CNTs into liposomes and the separation performance of thin-film nanocomposite (TFN) membranes. The results show that the addition of DOTAP increased the quantity of CNTs inserted into the liposome vesicles, as the shrinkage rate (k) and permeability (Pf) of the liposome vesicles presented an obvious increase with the increased content of DOTAP in the liposome vesicles. Moreover, it contributed to a 252.3% higher water flux for TFN membranes containing DOPE/DOTAP2:1-CNT liposomes (the mass ratio between DOPE and DOTAP was 2:1) than thin-film composite (TFC) membranes. More importantly, it presented a 106.7% higher water flux for TFN membranes containing DOPE/DOTAP4:1-CNT liposomes (the mass ratio between DOPE and DOTAP was 4:1), which originated from the greater number of water channels that the CNTs provided in the liposome vesicles. Overall, positively charged DOTAP effectively tailored the vesicle charge, which provided a better carrier for the insertion of a greater quantity of CNTs and contributed to the higher permeability of the TFN membranes.
]]>Separations doi: 10.3390/separations11030074
Authors: Tahir Khan Jinna Zhou Yingqi Guo Donghai Hou Na Pi Yinlong Yang Hong Yu
Cordyceps fumosorosea is a common species within the Cordyceps genus. In this study, the protective effect of Cordyceps fumosorosea mycelium was investigated to clarify the potential mechanism of alleviating acute lung injury in mice using serum metabolomic analysis, which could provide a theoretical basis for the clinical application of C. fumosorosea. Sixty mice were divided into six groups (NS, LPS, MIX, COR, COC and DMX). Lung cell nuclei were analyzed using hematoxylin and eosin staining and cellular changes were observed using transmission electron microscopy (TEM). Metabolomic analyses using liquid chromatography-mass spectrometry (LC-MS) were used to identify various compounds. In all six groups, lung nuclear inflammation was observed in the COR, COC and DMX groups, whereas the NS, LPS and MIX groups showed no cellular changes, indicating good health. Metabolomic analysis using LC-MS identified 1607 compounds across various classes. Statistical analyses, including the coefficient of variation and OPLS-DA, revealed distinct metabolic proles, indicating significant changes after the consumption of C. fumosorosea mycelia. Lipids constituted the largest proportion (30.37%) of the 30 identified classes and subclasses of metabolites. A total of 617 differentially accumulated metabolites (DAMs) were identified, both unique and shared between comparisons. Metabolite analysis identified 617 differentially accumulated metabolites, with 493 common to the LPS vs. MIX group, 75 in the LPS vs. NS group and 49 in the LPS vs. NS group and LPS vs. MIX group. This comprehensive investigation suggests that C. fumosorosea mycelia treatment holds promise as a therapeutic intervention for lung injury, influencing both the histopathological (lung) features and serum metabolic profiles.
]]>Separations doi: 10.3390/separations11030073
Authors: Sónia Mendes Tiago Q. Faria André Nascimento Marc Noverraz Franziska Bollmann Piergiuseppe Nestola António Roldão Cristina Peixoto Ricardo J. S. Silva
Adeno-associated viruses (AAV) are currently predominant viral transfer tools for gene therapy, and efforts are being made to design faster and more efficient methods and technologies for their manufacturing. The early selection of high-performing filters is essential for developing an ultrafiltration and diafiltration (UF/DF) process, especially when feed material is scarce, and timelines are short. However, few methods and technologies exist to enable process optimization with multiple variations in a single run. In this study, we explored the potential of Ambr® Crossflow for high-throughput, automated screening of different membrane materials, pore sizes and different process conditions for the UF/DF step of AAV8. The best overall performance was obtained with a 100 kDa PES flat sheet cassette. The UF/DF process was further transferred to a larger scale to the Sartoflow® Smart Tangential Flow Filtration (TFF) system using a 100 kDa PES Sartocon® Slice 200 cassette and compared to a 100 kDa PES hollow fiber. Virus recovery, permeate flux and total protein removal values of the flat sheet cassette were similar to those achieved in small-scale devices, and higher than those of the hollow fiber, thus demonstrating similar performance at a larger process scale. The high-throughput, automated method described herein allowed to screen multiple materials and process parameters of a UF/DF process in a time- and resource-efficient way, making it a useful tool to accelerate early-stage downstream process development of AAV.
]]>Separations doi: 10.3390/separations11030072
Authors: Athanasios Ch. Mitropoulos Ramonna I. Kosheleva Margaritis Kostoglou Thodoris D. Karapantsios
Nanoporous materials offer a promising solution for gas storage applications in various scientific and engineering domains. However, several crucial challenges need to be addressed, including adsorptive capacity, rapid loading, and controlled gas delivery. A potential approach to tackle these issues is through rotation-based methods. In this study, we investigate the impact of rotation on CO2 adsorption using activated carbon, both at the early and late stages of the adsorption process. Towards this direction, three sets of experiments were conducted: (i) adsorption isotherm with rotation at each gas loading, (ii) adsorption kinetics with multiple rotations performed in sequence 15 min after CO2 introduction, and (iii) adsorption kinetics with a single rotation after 40 h of adsorption and repetition after another 20 h. For the first two cases, the comparison was performed by respective measurements without rotation, while for the last case, results were compared to a theoretical pseudo-first-order kinetic curve. Our findings demonstrate that rotation enhances the adsorptive capacity by an impressive 54%, accelerates kinetics by a factor of 3.25, and enables controllable gas delivery by adjusting the angular velocity. These results highlight rotation as a promising technique to optimize gas storage in nanoporous materials, facilitating advancements in numerous scientific and engineering applications.
]]>Separations doi: 10.3390/separations11030071
Authors: Aleksandra Sander Ana Petračić Domagoj Vrsaljko Jelena Parlov Vuković Patricija Hršak Antonija Jelavić
Following the trend of transport decarbonization, biodiesel has become a promising alternative fuel option. Its production includes multiple steps, all of which can be time-consuming and energy intensive. Improving any of these steps could bring considerable environmental and economic benefits. The utilization of deep eutectic solvents (DESs) for glycerol extraction from crude biodiesel has predominantly been explored as a batch process. This work provides insight into continuous column extraction. Different waste cooking oils were used to produce biodiesel via transesterification with methanol, and the selective solvent for purification was DES choline chloride–ethylene glycol (1:2.5, mol.). A laboratory Karr column at different pulsation frequencies and DES to biodiesel mass ratio was used for extraction. Plate material (steel and 3D printed PETG) and geometry influence on the efficiency of extraction were investigated. Contact angle measurement was used to measure the surface free energy of steel and PETG and the spreading ability of biodiesel and DESs on both materials. Extraction efficiency was analyzed by several analytical techniques. Higher efficiency was observed with steel plates of a triangular pitch hole arrangement. Increasing the mixing intensity and DES to biodiesel mass ratio further increased the efficiency of extraction.
]]>Separations doi: 10.3390/separations11030070
Authors: Nobuyuki Katagiri Takehiro Uchida Hironori Takahashi Eiji Iritani
Microfiltration plays an increasingly important role in various fields. Consequently, elucidating the mechanism of membrane fouling has emerged as a pivotal issue that needs to be resolved. In this study, a blocking filtration model was employed to evaluate the effects of membrane properties on the fouling mechanism during the microfiltration of representative polysaccharides, namely sodium alginate, pectin, and xanthan gum. Microfiltration membranes composed of hydrophilic and hydrophobic PVDF, mixed cellulose ester, as well as hydrophilic and hydrophobic PTFE were used as filter media. The flux decline behavior was significantly affected by the membrane properties, with hydrophilic membranes exhibiting a slower decrease in filtration rate. The model analysis revealed a correlation between the blocking characteristic values and the membrane properties. Although the blocking index n showed membrane material dependence, the values of this parameter remained consistent across various filtration conditions, including the wettability of the membrane surface, solute concentration, and pressure (pectin: n = 1.86, 1.85, 1.50, and 1.50 for hydrophilic PVDF, hydrophobic PVDF, hydrophilic PTFE, and hydrophobic PTFE, respectively). The resistance coefficient k was influenced by the characteristics of the membrane surface; the k values of the hydrophobic membranes were higher than those of the hydrophilic ones (pectin: k = 0.00084, 0.00725, 0.00714, and 0.0384 s1−n/cm2−n for hydrophilic PVDF, hydrophobic PVDF, hydrophilic PTFE, and hydrophobic PTFE, respectively). The model calculations, based on the values of n and k, demonstrated a relatively good agreement with the experimental data.
]]>Separations doi: 10.3390/separations11030069
Authors: Igor G. Zenkevich Abdennour Derouiche
Background: Recurrent approximation of retention parameters in reversed-phase HPLC is effective for revealing anomalies that are otherwise difficult to detect, namely, the reversible hydration of analytes. This was demonstrated previously for restricted sets of analytes with acetonitrile–water eluents. Expanding the number of analytes and eluents seems to be a topical problem. Two kinds of derivatives of aromatic carbonyl compounds were characterized: unsubstituted hydrazones and oximes. Methods: If analyte demonstrates no anomalies in dependences of retention times vs. concentration of organic modifier, the recurrent approximations of these dependences are linear. To explain the features of recurrent approximations, the numerical experiments were proposed and considered. The artificial shifting of one, two, or more points allows for the modeling the different kinds of deviations of approximations from linearity. Results: It was shown that hydrazones are the class of analytes having no anomalies of retention parameters. On the contrary, several anomalies were detected for oximes. Downward deviations of points in the plots of recurrent approximations of retention times are the signs of reversible hydration. This effect for methanol–water eluents was detected for the first time. Some of oximes underwent hydrolysis. Conclusions: Recurrent approximation of retention times allows detecting chemical transformations of analytes during RP HPLC analysis.
]]>Separations doi: 10.3390/separations11030068
Authors: Jun Xiang Qi Liu Huihua Jing Xiaoqing Chen
Camellia oil is a high-value product with rich nutrients. Recently, the adulteration of camellia oil has become an increasingly concerning issue related to human health. In this study, electric soldering iron coupled with rapid evaporative ionization mass spectrometry (REIMS) was employed for the identification and analysis of camellia oil without any sample preparation. REIMS technology coupled with chemometrics was applied to develop an analysis model for the authentication of camellia oil adulterated with soybean oil, peanut oil, rapeseed oil, sunflower oil, and corn oil (5–40%, v/v). The results showed that different types of vegetable oils could be classified using principal component analysis-linear discriminant analysis (PCA-LDA) with a correct classification of 93.8% in leave-20%-out cross-validation and 100% correctly identified in real-time recognition. The established prediction models were found to be particularly sensitive when the camellia oil samples were adulterated with 5–40% of other oils, indicating that REIMS could be a powerful tool for the authentication and adulteration analysis of camellia oil, particularly for cases where the adulteration levels are relatively high. In conclusion, the results provide valuable insights into the potential of REIMS for the rapid, accurate, and real-time authentication and adulteration analysis of camellia oil.
]]>Separations doi: 10.3390/separations11030067
Authors: Patroklos Vareltzis Dimitrios Fotiou Vasiliki Papatheologou Smaro Kyroglou Efthymia Tsachouridou Athanasia M. Goula
Lavender distillation produces huge quantities of solid waste yearly. This waste is usually discarded, resulting in serious environmental issues. However, it still contains residual essential oil and other bioactive compounds. This research reports on the development and comparison of optimized solid–liquid separation methods, i.e., microwave- (MAE) and ultrasound-assisted extraction (UAE) of phenolic compounds from lavender distillation waste. The optimal pretreatment conditions, such as waste moisture content and particle size, were also determined. The extracts were spray- or freeze-dried and the resulting powders were characterized for their physicochemical properties. The majority of the original phenolic compounds in lavender were found in the leachate fraction after distillation (61%), whereas 43% was found in the solid waste. Drying of the solid waste before extraction affected the process efficiency. UAE led to a higher phenolic content and greater antioxidant properties compared to MAE. Drying (spray or freeze) the extracts did not significantly affect their phenolic content, whereas the use of maltodextrin as a drying agent improved the drying process yield, especially when using the freeze-drying method. It is concluded that valorization of lavender distillation wastes can be achieved via an integrated process consisting of a green extraction method and a consequent drying process that results in a stable bioactive powder.
]]>Separations doi: 10.3390/separations11030066
Authors: Calogero Cuttaia Barbara Di Stefano Solange Sorçaburu Ciglieri Raffaella Vetrini Carlo Previderè Paolo Fattorini
Body fluid identification is fundamental in forensic science as it links a specific biological source to a genetic profile, thus providing critical clues for crime scene reconstruction. Blood is one of the most common body fluids found on the crime scene, and several strategies have been developed for its identification in recent decades. Usually, after a preliminary (or presumptive) test to determine the presence of blood (both human and non-human), a confirmatory test is needed to prove that the sample is human blood. Out of the confirmatory tests, immunochromatographic (IC) assays are the most commonly and widely used. This work gives a review of the use of commercial kits specifically developed to detect human hemoglobin or glycophorin A (a surface protein of human red cells) in forensics. Claimed sensitivity varies broadly (ranging from 0.06 to 75 nanoliters of fresh blood), but different values (as low as 0.002 nL) were found during validation procedures. Specificities are high, and the possibility of cross-reaction (with the risk of false-positive results) is so low that it can be considered negligible. False-negative results, however, can be found due to the so-called “hook effect” as well as to the target degradation/modification, which interferes with the Ag-Ab binding. In addition, the chemical compositions of the presumptive test, detergents, and washing can also promote false negative outcomes in peculiar situations. Although IC assays are rapid, inexpensive, specific, and easy to use even on the crime scene, their major limitation is represented by the destructive approach required by this kind of confirmatory test. Since the final goal of the forensic investigation is the genetic typing of a bloodstain, we will describe the strategies developed for IC assays of faint stains as well as the strategies adopted to ensure that exactly the same sample undergoes human blood identification and DNA typing.
]]>Separations doi: 10.3390/separations11030065
Authors: Bum Soo Lee Yun Young Lee Seoung Rak Lee Yoon Seo Jang Rhim Ryoo Wooram Park Se-Na Kim Soah Lee Chun Gwon Park Ki Hyun Kim
Podostroma cornu-damae, one of the lethal toxic mushrooms, is known to contain macrocyclic trichothecene mycotoxins exhibiting potent cytotoxic effects, attracting attention as an important research subject for scientists interested in natural product chemistry and toxicity research. To investigate the mycotoxins from the toxic mushroom P. cornu-damae and evaluate their cytotoxic activities, the fungus was large-cultured on solid plates and successively extracted to acquire a crude methanol (MeOH) extract. After performing successive separation and purification processes, a total of eight macrocyclic trichothecenes were isolated from the MeOH extract of plate cultures of P. cornu-damae using the liquid chromatography/mass spectrometry (LC/MS)-guided isolation technique. Extensive interpretation of nuclear magnetic resonance (NMR) spectroscopic and high-resolution (HR)-electrospray ionization (ESI)-MS data allowed for the structural identification of all isolated macrocyclic trichothecenes, including satratoxin I (1), satratoxin H (2), roridin E (3), miophytocen D (4), roridin L-2 (5), trichoverritone (6), 12′-episatratoxin H (7), and roridin F (8). We conducted a cytotoxicity evaluation of compounds 1–8 against 4T1 breast cancer cells and fibroblast cell lines (L929 cells) using the Counting Kit-8 (CCK-8) cell viability assay to validate their cytotoxic potential. Our results indicated that compounds 1–6 lack anti-cancer effects on 4T1 cells and have minimal impact on the viability of the fibroblast cell line, L929 cells. In contrast, compounds 7 and 8 exhibited no cytotoxicity in normal cells (L929) and demonstrated specific cytotoxicity in breast cancer cell lines. Notably, the cytotoxic effects of compounds 7 and 8 in 4T1 cells were significantly stronger than those observed with free doxorubicin. These findings suggest that compounds 7 and 8 may possess targeted anti-cancer effects, specifically against breast cancer cells, emphasizing their efficient and selective toxicity towards breast cancer cells.
]]>Separations doi: 10.3390/separations11020064
Authors: Roberto Castro-Muñoz
In new food formulations, carotenoids and phenolic compounds are likely to be the most sought after food ingredients according to their bioactivity, nutraceutical, nutritional value, and compatibility properties once incorporated into food formulations. Such solutes are naturally present in many plant-based sources, and some portions are directly consumed when enriching food products and formulations; however, some portions, which are contained in the parts of the plant sources not considered edible, including the leaves, peel, and seeds, among other by-products, are commonly wasted. Related to this, scientists have found a new window for obtaining these bioactive molecules, but their recovery remains a challenge. To some extent, the final purification and polishing requires highly selective performance to guarantee the desired properties and concentration. In this regard, membrane technologies, such as nanofiltration (NF), represent an alternative, owing to their highly selective properties when separating low-molecular-weight compounds. NF becomes immediately suitable when the pretreated extracts are subjected to further efficient concentration, fractionation, and polishing of phenolic fractions and carotenoids. The separation efficiency (usually higher than 97%) of NF technology is high according to the low pore size of NF membranes, but the low temperature in process separation also contributes to the separation of thermolabile compounds. Therefore, this paper reviews the ongoing cases of studies reporting the successful separation and polishing of phenolic fractions and carotenoids from distinct sources. In particular, we have focused our attention on the main interactions during the separation process and the drawbacks and advantages of using membranes for such a case study.
]]>Separations doi: 10.3390/separations11020063
Authors: Shengyang Zheng Yaping Xu Xu Yao Chenzhe Wang Ping Liu Haitao Zhao Jianbing Lu Jing Ju
The widespread use of tetracycline (TC) poses potential hazards to ecosystems and human health. In this study, ZIF-67 was successfully synthesized using a room-temperature static synthesis method and applied to the efficient removal of TC from water. It was shown that the maximum adsorption of TC by ZIF-67 could reach 1583.128 mg·g−1 at pH = 5.0, an initial TC concentration of 450 mg·g−1, an adsorption time of 720 min, and a temperature of 308K.The pseudo-second-order kinetic model and Langmuir’s isothermal adsorption model could describe the adsorption process better, which proved that the adsorption of ZIF-67 on TC was mainly monolayer adsorption dominated by chemisorption. Mechanistic studies showed that the adsorption process of ZIF-67 on TC was mainly through electrostatic interactions, pore adsorption, π–π interactions, and framework coordination of ZIF-67 surface cations with TC.
]]>Separations doi: 10.3390/separations11020062
Authors: Alexandre Janeiro Ana Lima Filipe Arruda Tanner Wortham Tânia Rodrigues José Baptista Elisabete Lima
Cryptomeria japonica (Thunb. ex L.f.) D. Don (Cupressaceae) is widely cultivated in the Azores archipelago (Portugal) for landscaping and timber production, generating a huge amount of biomass residues. Among these, female cones (FC) emerge as a source of particularly valuable essential oils (EOs), namely, as promising broad-spectrum antimicrobial agents. However, phytochemical research on C. japonica FC EOs remains scarce. This study evaluated the EO yields and chemical compositions of immature and mature FC (IFC and MFC) from the same batch of Azorean C. japonica. IFC and MFC EOs, obtained via hydrodistillation, presented different yields (0.72% vs. 1.12% w/w, dry weight), and their composition, determined via gas chromatography/mass spectroscopy, revealed that the monoterpenes class was dominant (51.84% vs. 69.13%), followed by the sesquiterpenes (36.44% vs. 26.28%) and diterpenes (10.96% vs. 3.03%) classes. However, the correspondent oxygen-containing terpenes classes were 1.5–2.0 times higher in IFC. Thus, the maturation process revealed an increase in EO yield and α-pinene content (19.5% vs. 41.3%) but a decrease in other important bioactive terpenes/terpenoids (terpinen-4-ol, bornyl acetate, elemol, γ-eudesmol, phyllocladene, and nezukol) content. In conclusion, IFC and MFC EOs, due to their unique composition, may have differential commercial applications and, consequently, contribute to increasing the commercial potential of C. japonica’s EO industry.
]]>Separations doi: 10.3390/separations11020061
Authors: Madasamy Sundar Gopalan Rajagopal Ambikapathi Nivetha Seetharaman Prabu Kumar Selvaraj Muthukumar
In this study, we biosynthesized the stable silver nanoparticles (AgNPs) from Momordica cymbalaria leaves to evaluate their antioxidant, antibacterial, cytotoxic, and photocatalytic properties. Initially, we screened the bioactive compounds from M. cymbalaria extract using GC-MS. The biosynthesis of Mc-AgNPs was confirmed using instruments, such as UV-visible spectroscopy FT-IR, XRD, SEM with EDX, and HR-TEM analyses. The UV-visible spectrum indicated absorbance at 425 nm. The crystallite size of the M. cymbalaria-stabilized nanoparticles was determined to be 20.14 nm. The morphology and size of the synthesized Mc-AgNPs were confirmed via SEM-EDX and HR-TEM analyses, with a size range from 16 to 22 nm. The synthesized Mc-AgNPs exhibited a photocatalytic yield of 60%. The biosynthesized Mc-AgNPs demonstrated strong antioxidant properties and prominent antibacterial activity against human pathogenic bacteria. The cytotoxicity study revealed that Mc-AgNPs were effective against MCF-7 cells in a dose-dependent manner. The recognized bioactivities confirm that the synthesized Mc-AgNPs act as effective catalysts in oxidation and serve as potent antioxidant, anticancer, and antibacterial agents.
]]>Separations doi: 10.3390/separations11020060
Authors: Patroklos Vareltzis Panagiota Karatsioli Ioannis Kazakos Anna-Maria Menelaou Konstantina Parmaxi Vangelis Economou
The food industry is seeking a stable, non-toxic red dye as a substitute for synthetic pigments. This can result from the reaction between 5-O-Caffeoylquinic acid (5-CQA) and tryptophan (TRP). This study explores the reaction kinetics under ultrasound conditions and investigates reaction parameters, such as pH, temperature, and reactants’ concentrations, to accelerate the reaction. At the end of the reaction, the solution was either spray-dried or acidified to isolate the pigment, which was evaluated for its potential as a food dye. Using ultrasound at 40 °C led to a significant acceleration of the reaction that was completed in 8.5 h, marking a 300% improvement compared to literature. The caffeic acid, and not the quinic acid, moiety of 5-CQA seems to be partly responsible for the formation of the red pigment. The pH had a profound impact on the reaction rate, with an optimal value of pH = 9.5. Increased TRP concentrations led to increased reaction rates, while higher 5-CQA concentrations led to significant deviations from redness (a* value). The pigment, lacking significant antimicrobial activity, exhibited remarkable thermal stability (pH 3–9), delaying food oxidation and color deterioration. The results indicate that the reaction can be significantly accelerated by ultrasound, which will be useful for the scale-up of the process and giving the produced pigment the potential for use as an alternative to artificial coloring.
]]>Separations doi: 10.3390/separations11020059
Authors: Zeinab Rabiei Andrew Simons Magdalena Folkmanova Tereza Vesela Ondrej Uhlik Evguenii Kozliak Alena Kubátová
Lignin, a complex and abundant biopolymer, is a major constituent of plant cell walls. Due to its chemical and structural complexity, lignin degradation is a challenging task for both natural and engineered systems. Therefore, investigation of lignin degradation using so called “model compounds” has been the focus of many research efforts in recent years. This study addresses the utility of guaiacylglycerol-β-guaiacyl ether (Gβ2) as a model compound for evaluating the β-O-4 bond cleavage under diverse thermal and aqueous medium conditions. Experimental conditions included varied pH (3–10), microbial biodegradation, subcritical water environment (150–250 °C), and mild pyrolysis (150–250 °C). A high-performance liquid chromatography with high-resolution mass spectrometry was employed for accurate detection and quantification of both Gβ2 and its degradation/modification products in an aqueous environment. Pyrolysis experiments were performed using gas chromatography-mass spectrometry analysis with a pyrolyzer. The results showed that Gβ2 remained stable under exposure to moderate pH and several bacterial strains, which were successfully used previously for biodegradation of other recalcitrant pollutants. We report, for the first time, differing Gβ2 breakdown pathways for subcritical water treatment vs. pyrolysis under an inert atmosphere. The scientific novelty lies in the presentation of differences in the degradation pathways of Gβ2 during subcritical water treatment compared to pyrolysis in an inert atmosphere, with water playing a key role. The observed differences are ascribed to the suppression of homolytic reactions by water as a solvent.
]]>Separations doi: 10.3390/separations11020058
Authors: Nadin Boegelsack James Walker Court D. Sandau Dena W. McMartin Jonathan M. Withey Gwen O’Sullivan
Producing defensible data for legal proceedings requires strict monitoring of sample integrity. In fire debris analysis, various approved packaging and storage solutions are designed to achieve this by preventing cross-contamination. This study examines the efficiency of current practices at preventing cross-contamination in the presence of a sample matrix (charred wood) via analysis by comprehensive multidimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-ToF MS). The transfer of ignitable liquid residue (ILR) was assessed by comparing percentages of the target ILR area relative to the total chromatogram area and applying chemometric tools developed to detect cross-contamination. All practices reduced cross-contamination in comparison to faulty packaging. Individual practices varied in their performance. Nylon-based packaging performed best, whereas commercial polyethylene-based packaging performed worst due to interfering compounds emitted from the material and sealing mechanism. Heat-sealing was the best sealing mechanism when applied correctly, followed by press-fit connections, and lastly, adhesive sealing. Refrigerated storage offered several advantages, with elevated impact for polyethylene-based packaging and adhesive sealing mechanisms. Triple-layer packaging practices did not show significant benefits over double-layers. The recommended packaging approach based on these findings is mixed-material packaging (metal quart can in a heat-sealed nylon bag), offering advanced prevention of cross-contamination and practical advantages with continued refrigeration during transport.
]]>Separations doi: 10.3390/separations11020057
Authors: Krastena Nikolova Nadezhda Petkova Dasha Mihaylova Galia Gentscheva Georgi Gavrailov Ivaylo Pehlivanov Velichka Andonova
Phycocyanin is a pigment–protein complex from the group of phycobiliproteins obtained from Spirulina (Arthrospira platensis), with possibilities for various applications in food and pharmaceutical technologies. It is a natural colorant for food and cosmetic products. This study aimed to investigate the effect of ultrasonic and microwave extraction conditions on antioxidant activity (AOA), chlorophyll content, and the content and purity index of phycocyanin in aqueous and alcoholic extracts of Spirulina (Arthrospira platensis). For this purpose, ultrasonic extraction with water or ethanol was performed at 20 °C, 30 °C, and 40 °C for 1, 2, and 3 h at an ultrasonic frequency of 36 kHz, 40 kHz, and 45 kHz. Microwave water extraction was performed for 60 s, 120 s, and 180 s. For each of the obtained samples, three parallel measurements of antioxidant activity were made by DPPH and FRAP methods, and chlorophyll content and phycocyanin yield and purity index were determined spectrophotometrically. Ultrasonic extraction resulted in a higher yield and purity index of phycocyanin compared to microwave extraction. The highest yield of 14.88 mg g−1 with a purity index of 1.60 was achieved at a temperature of 40 °C for one hour and an ultrasonic wave frequency of 40 kHz. A relatively low yield of 4.21 mg g−1, but with a purity index of 2.67, was obtained at a temperature of 30 °C, a time of two hours, and an ultrasonic frequency of 40 kHz. Chlorophyll b content at 20 °C, for two hours and ultrasonic frequency 40 kHz was 1.400 mg g−1. The study proposes ultrasonic extraction as a green method to obtain phycocyanin of varying purity index that may be used for food, cosmetic, or biomedical purposes.
]]>Separations doi: 10.3390/separations11020056
Authors: Felix Buthmann Philip Laby Djamal Hamza Jörg Koop Gerhard Schembecker
Centrifugal Partition Chromatography (CPC) is a separation technique that utilizes immiscible liquid phases to purify compounds. The selection of solvents in Liquid–Liquid Chromatography offers flexibility and optimization possibilities for specific separation tasks. Understanding the hydrodynamics inside the apparatus is crucial for optimizing a CPC process. The phase retention ratio (Sf) determines the apparatus’s operating point and separation efficiency. However, stationary phase leakage, known as bleeding, complicates the immobilization of this phase. We used a partly transparent single-disc rotor to investigate the time and space dependency of bleeding inside a CPC apparatus, enabling real-time and localized determination of the phase retention ratio. By tracking the retention values over time, we observed the bleeding phenomenon and its progression from the inlet to the rotor outlet. Depending on the phase system used, the CPC was utilizable for a separation task for only 173–500 dimensionless residence times. Systems with a higher stability parameter (as described in the literature) showed a lower bleeding rate and increased stability over time. Accordingly, our results demonstrate the importance of maintaining an optimal ratio of mobile to stationary phase for efficient separation.
]]>Separations doi: 10.3390/separations11020055
Authors: Ayah Nader Abu-shark Ashok K. Shakya Safwan M. Al-Adwan Rajashri R. Naik
Perampanel, a novel α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, is registered for the adjunctive treatment of patients (aged ≥ 12 years) with refractory partial-onset seizures. A simple high-performance liquid chromatographic method fluorescence detection (HPLC-FLD) was developed to analyze perampanel in rats’ plasma and validated for bioanalytical purposes. Rats’ plasma (50 µL) was processed by microextraction packed sorbent (MEPS). The analytes were separated using a Hypersil Gold octadecyl silane column (250 × 4.6 mm internal diameter, 5 μm particle size) with isocratic elution. A mobile phase consisting of acetonitrile–methanol–water (275:275:450, v/v/v; containing 50 µL triethylamine and pH adjusted to 3.25 with orthophosphoric acid) was used in this analysis. The flow rate was 1.25 mL/min. Analytes were monitored at an excitation wavelength of 285 nm and an emission wavelength of 430 nm. The linearity range for this validated method was from 3.75 to 300 ng/mL. No endogenous peaks were found in the elution of analytes in drug-free rats’ plasma. Intra- and inter-batch reproducibility studies demonstrated accuracy and precision within the acceptance criteria. The results indicate that the present method is simple, selective, reproducible, and suitable for the analysis of perampanel in small volume samples. The robustness of the method was accessed using MODDE® design of experiments software version 12.5.
]]>Separations doi: 10.3390/separations11020054
Authors: Alessia Panusa Paola Rotundo Daniele Sadutto Andrea Rodomonte Roberto Cirilli
1-amino-4-methyl-piperazine (AMP) is both a starting material for the synthesis of rifampicin (RIF) and a degradation product of RIF hydrolysis. 1-methyl-4-nitroso-piperazine (MNP) is an oxidation product of AMP as well as a potentially genotoxic N-nitrosamine. The EMA and FDA have approved an ad interim limit of 5 ppm for MNP in RIF drug products. As in-house methods for the analysis of MNP in RIF use a wide range of conditions for mobile phases and sample diluents, we decided to investigate whether these conditions affect the formation of MNP and AMP. A UHPLC-MS/MS method was developed to simultaneously quantify AMP and MNP during RIF hydrolysis in buffered aqueous solutions at different pH levels. Analyses were performed in MRM mode; separations were carried out on an InfinityLab Poroshell HPH-C18 (100 mm, 2.1 mm i.d., particle size 1.9 μm). In aqueous RIF solutions, the content of AMP and MNP increases with time; at different pHs, the concentration of AMP increases much faster in acidic than in basic solutions; and the increase in MNP can be reduced by the addition of ascorbic acid. To avoid an overestimation of MNP, water should not be used as a diluent in RIF sample preparations. Methanol is a more suitable diluent than water. A standard addition method has been validated for the quantification of MNP in RIF drug substances.
]]>Separations doi: 10.3390/separations11020053
Authors: Daniele Naviglio Angela Perrone Francesca Varchetta Paolo Trucillo Domenico Montesano Monica Gallo
Food adulteration consists of changing the original structure of a food, and so, by its definition, it is a process not admitted by law. Adulterations can not only have commercial consequences, but also hygienic and nutritional ones, and in some cases, they can cause a serious danger to public health. Therefore, it is of great interest to understand and identify the modifications that alter the original chemical composition of a food item (nutrition label). Among the food processing sectors, the pasta food chain is a fascinating production process, which finds its roots in a mixture of a few, simple ingredients; in particular, in its basic formulation to produce pasta, exclusively durum wheat mixed with water is used, while soft wheat and therefore the flour obtained from it are destined for bakeries and the confectionery industry. In this work, a procedure was developed that allows the detection of the possible presence of soft wheat in durum wheat-based products, both in the flour and after the pasta-making process. It is to point out that this adulteration is only commercial fraud and there are no consequences for people’s health. In detail, the method was based on the isolation of the lipid fraction of flours and pastas and using the gas chromatographic analysis of the sterol ester fraction, which were not altered during the pasta-making phase, because they have very high boiling points. Based on the evaluation of some specific ratios between sterol esters, it was possible to trace the percentage of soft wheat present in a mixture with durum wheat, both in flour products and pastas.
]]>Separations doi: 10.3390/separations11020051
Authors: Pamela Cabarcos-Fernández María Jesús Tabernero-Duque Iván Álvarez-Freire Ana María Bermejo-Barrera
Dispersive liquid–liquid microextraction, an environmentally friendly extraction technique, followed by gas chromatography–mass spectrometry operating in selected ion monitoring (SIM) mode, is here presented for the simultaneous determination of two anticonvulsant drugs in plasma, Topiramate and Carbamazepine. Experimental parameters affecting the recovery of the proposed extraction method, such as the extraction and dispersion solvent, the extraction and dispersion volume, the sample amount, the pH of the aqueous phase, the ultrasound time, the centrifugation time and ionic strength, were investigated. The limits of detection for Topiramate and Carbamazepine were 0.01 and 0.025 µg mL−1, and the limits of quantification were 0.025 µg mL−1 and 0.05 µg mL−1, respectively. The method is shown to be selective, accurate, precise and linear over the concentration ranges of 0.025–8 µg mL−1 for Topiramate and 0.05–3 µg mL−1 for Carbamazepine. The extraction recovery of the analytes ranged from 91.5% to 113.9%. The analytical method was successfully applied to real plasma samples received by the Forensic Toxicology Service of the Forensic Science Institute of Santiago de Compostela.
]]>Separations doi: 10.3390/separations11020052
Authors: Luz Fanny Echeverri-Giraldo Valentina Osorio Pérez Claudia Tabares Arboleda Lady Juliet Vargas Gutiérrez Luis Carlos Imbachi Quinchua
Cesar, a coffee-growing department in Colombia, has particular characteristics that favor the production of coffees differentiated by sensory profile, for which the acidity attribute stands out. The chemical composition and sensory quality of the coffee produced by 160 coffee growers during two production harvests (2021 and 2022) and processed by the wet method were evaluated to correlate the contents of the main acidic chemical compounds present in green coffee beans with the perceived acidity of the beverage. The chemical analysis of coffee samples utilized spectrophotometric methods and HPLC-DAD techniques. Lactic, 3,5-di-CQA and phosphoric acids were good discriminators of acidity classified as excellent; that is, with a score higher than 7.75 on the Specialty Coffee Association (SCA) scale, presenting the highest contents in the green coffee bean. There was a direct linear relationship between acidity and 3,5-di-CQA and 5-CQA and an inverse relationship between acidity and 3-CQA, 4-CQA and 4,5-CQA. These findings contribute to the understanding of the quality and chemistry of Colombian coffee.
]]>Separations doi: 10.3390/separations11020050
Authors: Uday M. Muddapur Samiksha Manjunath Yahya S. Alqahtani Ibrahim Ahmed Shaikh Aejaz Abdullatif Khan Basheerahmed Abdulaziz Mannasaheb Deepak Yaraguppi Sunil S. More
The main objective of this research was to perform Gymnema sylvestre (Asclepiadaceae) extract’s phytochemical screening and identify its therapeutic potential. Using a Soxhlet apparatus, the powdered plant material was extracted using ethyl acetate. The preliminary phytochemical analysis confirmed the presence of alkaloids, flavonoids, phenols, glycosides, and steroids. Gas chromatography–mass spectroscopy analysis of the extract was performed and confirmed the presence of 11 compounds. As per the quantitative analysis, the extract exhibited a phenolic content of 948 µg gallic acid equivalent/g dry weight, a total flavonoid content of 398 µg quercetin equivalent/g dry weight, and an alkaloid content of 487 µg atropine equivalent/g dry weight. As per the in vitro cytotoxicity test using A549 cells, the IC50 (half-maximal inhibitory concentration) value for the extract was found to be 76.06 ± 1.26 µg/mL, indicating its cytotoxic effect on the cells. The ethyl acetate extract showed significant antibacterial efficacy, as evidenced by a zone of clearance measuring 3 mm against Escherichia coli and 6 mm against Bacillus subtilis. For anthelmintic activity, the earthworm paralysis time induced by G. sylvestre extract (10 mg/mL) was 28.13 ± 0.8 min, and the time of death was 68.21 ± 1.72 min. In comparison, the reference drug, piperazine citrate (10 mg/mL), caused paralysis in 22.18 ± 1.02 min and resulted in death at 66.22 ± 2.35 min. Similarly, the coagulation time was notably prolonged, with blood clot formation observed at 1 min and 40 s, at a concentration of 1 mg/mL, which underscores the potential anticoagulant or hemostatic modulation properties of G. sylvestre extract. The test extract showed good inhibition of alpha-amylase activity and exhibited an IC50 value of 15.59 µg/mL. The IC50 value for DPPH (2,2-diphenyl-1-picrylhydrazyl)-scavenging activity for the extract was 19.19 µg/mL. Based on the GCMS results, the compound 2,7-dimethyl-undecane was selected for its anticancer potential. Docking studies were conducted with the epidermal growth factor receptor (EGFR) protein, specifically the 5WB7 variant associated with lung cancer. The docking score was −4.5, indicating a potential interaction. Key interaction residues such as ASN328, VAL350, and THR358 were identified. Overall, this research provides valuable insights into the phytochemical composition and diverse biological activities of G. sylvestre extract, offering a foundation for further exploration of its medicinal and pharmacological potential.
]]>Separations doi: 10.3390/separations11020048
Authors: Xing Xie Mangmang Li Dan Lin Bin Li Chaoen Li Dongjing Liu
Recently, salt-assisted pyrolyzation has been deemed an emerging and efficient method for the preparation of biochars due to its facile operation as well as its good structural and chemical properties. In this work, biochars (MBCx) are prepared by heating bamboo powders in eutectic salts (Li2CO3 + K2CO3) at 500–600 °C in the air. Multiple technologies are employed to examine the physiochemical properties of bamboo biochars. Correlations between heating temperature and structural features and carbon dioxide uptakes of bamboo biochars have been investigated. The results show that heating temperature has a significant influence on the physicochemical properties of bamboo biochars. With the elevation of the heating temperature, the defect structures of bamboo biochars gradually ascend, especially when the heating temperature reaches 600 °C. MBCx biochars visibly exceed conventional bamboo biochar prepared via pyrolyzation in a nitrogen stream free of salt addition. Pyrolysis of bamboo in eutectic salts endows biochars with higher oxygen content and more carbon defects, which likely accounts for their better CO2 capture activities.
]]>Separations doi: 10.3390/separations11020049
Authors: Klara Urbanova Andreas Romulo Marketa Houdkova Pavel Novy Ladislav Kokoska
This study assessed the antistaphylococcal activity of essential oil (EO) hydrodistilled from the rhizome of Curcuma mangga grown in Indonesia using the broth microdilution volatilization method and standard broth microdilution method modified for evaluation of volatile agents, as well as described its chemical composition using gas chromatography (GC) with mass spectrometry (MS). A fused-silica HP-5MS column and a DB-17MS column were used to separate the components into two columns. The results demonstrated that the EO exhibited antistaphylococcal activity at the minimum inhibitory concentration (MIC) ranging from 128 to 1024 µg/mL. In contrast, the clinical isolate of tetracycline-resistant Staphylococcus aureus was the most sensitive strain (MIC 128 µg/mL). The major constituents of the EO were 15,16-dinorlabda-8(17),11-dien-13-one (24.63/15.78%), followed by ambrial (16.12/10.97%), 13-nor-eremophil-1(10)-en-11-one (7.16/6.21%), 15,16-dinorlabda-8(17),12-dien-14-al (6.61/11.57%), and aromadendrene oxide (5.98/3.77%). These results propose C. mangga rhizome EO as a promising agent for developing natural-based anti-infective preparations.
]]>Separations doi: 10.3390/separations11020047
Authors: Gloria Melzi Corrado L. Galli Marina Marinovich
Extracts of Rheum palmatum L., Rhamnus purshiana DC., Rhamnus frangula L., and Cassia senna L. are used in traditional medicine thanks to their beneficial properties. These species contain hydroxyanthracene derivatives, considered genotoxic and possibly related to colorectal cancer development. This research aimed to study, using a micronucleus assay in vitro, the genotoxic potential of Rheum palmatum L., Rhamnus purshiana DC., Rhamnus frangula L. (bark), and Cassia senna L. (leaves and fruits) extracts. The extracts were evaluated at different concentrations: from 0 to 2000 µg/mL for Rhamnus purshiana DC, from 0 to 2500 µg/mL for Rheum palmatum L. and Rhamnus frangula L., and from 0 to 5000 µg/mL for Cassia senna L. The cytokinesis-block proliferation index was calculated to analyse if the used concentrations showed cytotoxicity. The hydroxyanthracene content varied between 0.06% and 0.23% for aloe-emodin, and between 0.07% and 0.16% for emodin and rhein. No cytotoxic effect was detected at any of these concentrations. Micronucleus analyses showed a lack of genotoxicity for all the extracts tested. These results show that Rheum palmatum L., Rhamnus purshiana DC, Rhamnus frangula L., and Cassia senna L. extracts do not induce genotoxicity since no increase in micronuclei formation in human lymphocytes in vitro was detected.
]]>Separations doi: 10.3390/separations11020046
Authors: Turki Kh. Faraj Mohamed Hamza EL-Saeid Mohamed M. M. Najim Maha Chieb
The assessment of pesticide residues in agricultural soils is an essential prerogative in maintaining environmental health standards. Intensive vegetable cultivation is practiced in the Al-Kharj area of the eastern Najd region of Saudi Arabia, where excessive applications of agrochemicals are reported to pollute vegetable-growing soils, challenging the sustainable management of soils and groundwater resources. This study aimed to monitor the levels of thirty-two types of pesticide residues in the soils of vegetable fields and the estimated potential health risk for humans due to non-dietary exposure to pesticides in soils in the Al-Kharj region. Pesticide residues were evaluated at 0–10 cm and 10–20 cm depths at 20 sampling sites from Al-Kharj. Gas chromatograph-mass spectrometry, coupled with a quadrupole mass spectrometer with a GC column, was used in the analysis. The results indicated that agrochemical residues show prolonged soil pollution that may cause adverse impacts on human and environment. Herbicides Atrazine, Isoproturpon, and Linuron have been detected in the soils, and these pose many problematic environmental threats. Bromoxynil, Pendimetholin, and Diclofop-methyl could be used as per the recommendations to sustainably manage soil and water resources in the Al-Kharj area. Resmethrin, Methidathion, Ethoprophos, Tetramethrin, Bromophis-methyl, Bifenthion, Permethrin, Fenoxycarb, Cyfluthrin, Phosmet, and Azinophos-methyl can be used safely in the Al-Kharj agricultural area, maintaining sustainable soils and water resources. Applications of Carbaryl require sufficient care, while Endosulfan, Deltamethrin, Lindane, Chlorpyrifos, Chlorpyrifos-methly, Dimethoate, Heptachlor, and Mevinphos, which are detected in soils, require policy guidelines to limit the use to ensure sustainability. Policy interventions need to be formulated to increase the sustainability of soil management and groundwater resources in the Al-Kharj region to ensure the safety of people who are in direct contact with the agrochemicals used and to ensure the safety of agricultural products generated in this region.
]]>Separations doi: 10.3390/separations11020045
Authors: Tomáš Crha Grace F. Odedina Jiří Pazourek
This article highlights the fundamental aspects of hydrophilic interaction liquid chromatography (HILIC) on poly-hydroxyl stationary phases to analyze non-derivatized mono- and disaccharides, including commonly consumed carbohydrates like glucose, fructose, sucrose, and lactose. The evaporative light-scattering detector (ELSD) is utilized as an alternative to an MS detector, and the separation system’s selectivity allows the separation of anomers of monosaccharides. The study also includes a rapid method for determining isomaltulose (Palatinose), which was validated and applied to food supplement samples available in the Czech market, even those with high protein content. Additionally, isomaltulose was separated from sucrose in just 13 min.
]]>Separations doi: 10.3390/separations11020044
Authors: Kenroy Wallace Racquel Wright Melisa Williams-Longmore Sasha-Gay Wright Helen Asemota
Dioscorea spp. is known for its myriad medicinal properties. D. alata, specifically crude extracts, have displayed potent anticancer properties. However, the chemical constituents of these extracts have not been examined. The aim of this study is to determine the chemical composition and antioxidant characteristics of the active extracts from D. alata tuber. Chemoinformatic profiling of the Jamaican Dioscorea alata cultivar white yam tuber was generated by a sequential Soxhlet extraction of dried milled tuber, producing five crude extracts: hexane (E-1), diethyl ether (E-2), acetone (E-3), ethanol (E-4) and water (E-5). The analytes within the five extracts were dissolved in 0.1% DMSO and their anticancer activity was determined using DU145 prostate cancer cells. Both the acetone and the ethanolic extract were able to induce greater than 50% cell death at 50 µg/mL. The order of growth inhibition of the extracts in DU-145 cell is E3 (IC50, 10.81 µg/mL) > E-4 (IC50 24.17 µg/mL) > E-1 (IC50 > 100 µg/mL) ≥ E-2 (IC50 > 100 µg/mL) ≥ E-5 (IC50 > 100 µg/mL). Phytochemical screening of both E-3 and E-4 revealed the presence of all major classes of secondary metabolites except tannins. Resins were also absent in the E-3 extract. Phenolic quantification indicated that E-3 and E-4 possessed GAEs of 31 ± 1.1 and 72 ± 1.8 mg per g of sample, respectively. Inversely, E-3 displayed greater antioxidant capability with IC50 of 82.9 µg/mL compared to E-4 (166.9 µg/mL); however, neither was comparable to citric acid (33.6 µg/mL). The extract E-3 was further isolated by HPLC into 11 fractions. Fractions 4 and 5 possessed potent cell growth inhibitory effects. GCMs of fractions 4 and 5 showed they possessed numerous saturated fatty acids with pharmacological relevance. The presence of these compounds shows potential for exploitation of D. alata extracts for pharmacological purposes.
]]>Separations doi: 10.3390/separations11020043
Authors: Georgios Kamaris Antonia Dalavitsou Catherine K. Markopoulou
Oxidative stress degrades skin collagen and elastin and causes inflammatory reactions that affect mitochondrial DNA leading to aging. In the present study, a potential cosmetic nano-emulsion (o/w) of seven substances (chlorogenic acid, caffeine, rutin, hesperidin, quercetin, α-tocopherol and retinol) with antioxidant and anti-aging properties was prepared and analyzed. The lipophilic components were entrapped in the dispersed nanoparticles (jojoba) of the emulsion while the hydrophilic ones dissolved in the aqueous phase (glycerol/water). Suitable excipients were selected using an experimental design methodology with two mixtures and two responses (particle size and zeta potential). The quantitative extraction of chlorogenic acid and caffeine from Crithmum maritimum L. plant and coffee beans (Coffea arabica L.) and their stability were also studied. The analysis of the substances was carried out on an HPLC-DAD, with a phenyl column and gradient elution system (solvent A: water with 0.2% formic acid and B: acetonitrile with 0.2% formic acid). Validation of the method was performed in terms of linearity (r2 > 0.998), precision and repeatability (%RSD < 2) while the limits of detection (LLODs) and quantification (LLOQs) were also determined. The antioxidants were quantified after being extracted from the substrate (%recovery 96.7–102.5, %RSD < 2).
]]>Separations doi: 10.3390/separations11020042
Authors: Simone Moretti Silvia Castellini Carolina Barola Elisabetta Bucaletti Chiara Petroselli Roberta Selvaggi Mara Galletti David Cappelletti Roberta Galarini
A quantitative analytical method for PFAS determination in airborne particulate matter (PM) has been developed using liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS), allowing for the determination of 33 compounds. The procedure was applied to ambient PM10 with limits of quantification for PFAS in the fg m−3 range. PM10 samples collected during a year-long campaign conducted in an urban site in Umbria (Central Italy) have been characterized for their PFAS content. Among the seven detected PFASs, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) were the most abundant compounds. Furthermore, this work allowed us to obtain the first seasonal trend of airborne PFASs in Central Italy. Seasonal trend analysis shows that PFAS concentration in the atmosphere peaks in summertime. A comparison with trends of other relevant primary and secondary air pollutants determined at the sampling site suggests a secondary nature of the observed PFAS, which are formed in the atmosphere directly from gaseous precursors and can contribute to worsen the urban air quality in summertime.
]]>Separations doi: 10.3390/separations11020041
Authors: Zhichao Zhang Hareem Siddiqi Yu-Ping Huang Shannon McClorry Peng Ji Daniela Barile Carolyn M. Slupsky
Hormones are important signaling molecules controlling physiological homeostasis. ELISA kits are commonly used to measure hormones; however, few ELISA kits are multiplex, not all species-specific ELISA kits are commercially available, and ELISA kits typically require a significant volume of biological fluids. Pigs resemble humans in digestive physiology, making them an excellent model in preclinical research of nutrition and metabolism. In this study, we developed and validated a simple liquid–liquid extraction procedure and LC-MS/MS method for the simultaneous quantification of insulin, cortisol, glucagon-like peptide-1 (GLP-1) (7-37) and (7-36), acyl and des-acyl ghrelin, and carboxylated osteocalcin in pig serum. The proposed method is specific, highly sensitive (LOQ in ng/mL and pg/mL), reasonably accurate (more than 76.2% of all quality control samples within 20% error from nominal values), and precise (intra-day CV ≤ 10% and inter-day CV ≤ 23.1%). The recoveries of all analytes and corresponding internal standards ranged from 83.7 to 116.0%. The method also requires a low serum volume of 50–100 μL, which is invaluable when sample volume is limited. These methods could be easily extended for use in other mammalian species.
]]>Separations doi: 10.3390/separations11020040
Authors: Siyuan Zhang Yuping Fan Xianshu Dong Xiaomin Ma Maoqing Yang Wei Xiao
This study aimed to increase the ammonium nitrogen adsorption capacity of lignite using ultrafine grinding, aiming to reduce eutrophication in water bodies. Ammonium sulfate (NH4)2SO4 was employed as a stand-in for ammonium nitrogen in water solutions. The lignite sample for adsorption was processed with varying milling times. Adsorption efficacy was assessed primarily through isothermal adsorption tests and other techniques. Additionally, the study delved into the adsorption mechanisms. The results demonstrate that lignite ground for 50 min follows monolayer adsorption, characterized by minimal pore size and reduced diffusion rates, thereby extending the time to reach equilibrium and maximizing adsorption. BET and SEM analyses show that coal powder is effectively ground by zirconia balls in a vertical stirring mill, diminishing its particle size and forming new micropores. Concurrently, larger native pores are transformed into mesopores and micropores, providing numerous sites for NH4+ adsorption. XPS and FTIR analyses indicate an increase in exposed carbonaceous surfaces and oxygen-containing functional groups in ultrafine lignite. Ammonium ions replace hydrogen in carboxyl groups to form COONH4, and hydrogen bonds may form between NH4+ and C-O groups. Additionally, the electrostatic attraction between NH4+ and the coal surface further enhances adsorption. It can be concluded that the physical grinding process increases the specific surface area and creates more active adsorption sites, which in turn, boosts NH4+ adsorption capacity. The maximum equilibrium adsorption capacity is as high as 550 mg/g. This study suggests that ultrafine lignite is a promising material for treating ammonia-nitrogen wastewater.
]]>Separations doi: 10.3390/separations11020039
Authors: Zhenhua Sun Qingxiang Shu Qikun Zhang Shaopeng Li Ganyu Zhu Chenye Wang Jianbo Zhang Huiquan Li Zhaohui Huang
ZSM-5 zeolite is a kind of high-value-added porous aluminosilicate zeolite. The use of the coal gasification slag utilization process by-product desilication liquid as a silicon raw material to replace the current raw materials such as water glass will help reduce production costs and achieve high-value utilization of solid waste. ZSM-5 zeolites for volatile organic compounds (VOCs) adsorption were prepared by a one-step hydrothermal method using the desilication solution prepared from coal gasification slag as the main silicon source and sodium source. The effects of crystallization reaction time, the crystallization temperature, the Na2O/SiO2 molar ratio, and the SiO2/Al2O3 molar ratio on the relative crystallinity and the specific surface area of the ZSM-5 zeolite were investigated and optimized. The optical reaction conditions were as follows: a crystallization time of 12 h, a crystallization temperature of 170 °C, a Na2O/SiO2 molar ratio of 0.2, and a SiO2/Al2O3 molar ratio of 200. The optimal ZSM-5 zeolite synthesized is hexagonal, with regular grains, a relative crystallinity of 101.48%, a specific surface area of 337.48 m2·g−1, and a pore volume of 0.190 cm3·g−1. And the optimal ZSM-5 zeolite was composed of SiO2 content of 97.52 wt%, Al2O3 content of 1.58 wt%, Na2O content of 0.33 wt%, and SiO2/Al2O3 molar ratio of 104.93. Na2O/SiO2 molar ratio is 0.0033. The results of static adsorption experiments show that the static adsorption capacities of ZSM-5 zeolite for p-xylene, benzene, toluene, and butyl acetate were 118.85, 69.98, 68.74, and 95.85 mg·g−1, respectively, which can effectively adsorb VOCs. The synthetic process of the ZSM-5 zeolite is a simple preparation process and short in synthesis time. The results of this study not only help to realize the high-value utilization of silicon components in solid waste, but also provide an economical and effective way to synthesize VOCs adsorption materials.
]]>Separations doi: 10.3390/separations11020038
Authors: Mladenka Jurin Darko Kontrec Marin Roje
A series of nine racemic trans-β-lactam ureas were analyzed for enantiomer separation by high-performance liquid chromatography (HPLC) and supercritical fluid chromatography (SFC). The separations were performed on three immobilized polysaccharide-based chiral analytical columns (CHIRAL ART Amylose-SA, CHIRAL ART Cellulose-SB and CHIRAL ART Cellulose-SC). In HPLC mode, a normal-phase consisting of n-hexane/2-PrOH (90/10, v/v), a polar organic mobile phase consisting of 100% MeOH or 100% EtOH, and a non-standard mobile phase consisting of 100% dimethyl carbonate (DMC) were investigated. In SFC mode, the mobile phases CO2/alcohol (80/20, v/v) and CO2/DMC/alcohol (MeOH or EtOH; 70/24/6, v/v/v or 60/32/8, v/v/v) were investigated. The best achieved enantioseparation of trans-β-lactam ureas was obtained with an Amylose-SA column. We have shown that the green solvent dimethyl carbonate (DMC) can be efficiently used as a mobile phase in HPLC mode as well as in SFC mode along with the addition of polar organic modifiers (MeOH or EtOH).
]]>Separations doi: 10.3390/separations11020037
Authors: Limin Yang Yue Chen Jinzhi Wang Yongzhen Luo Pengfei Zhou Xiaolai Zhang
In the R22 (chlorodifuoromethane) steam-cracking process, which is used to produce a TFE (tetrafluoroethylene) monomer, distillation is employed to separate the high-purity TFE monomer from the cracked gas generated during this procedure. Traditionally, this distillation process is carried out using five towers. In this study, the traditional five-tower distillation method was transformed into a four-tower distillation method through the Aspen Plus simulation software, and this process was simulated and optimized. Meanwhile, a double-effect distillation process was designed for the transformed four-tower distillation process. The transformed distillation process not only meets the requirements of 99.999% purity for the TFE monomer and 99.99% purity for R22 recycling, but it also reduces the footprint by eliminating one distillation tower and saves 112.9002 kW of tower load, thus reducing the operating costs. This research provides valuable guidance for practical production.
]]>Separations doi: 10.3390/separations11010036
Authors: Yea-Rok Park Bong-Seop Lee
Gallic acid, known for its biological activity contributing to human health, including antioxidant, anti-inflammatory, anticancer, and antimutagenic properties, was the focus of this study. The solubility of gallic acid was experimentally measured in pure and mixed solvents of water, ethanol, and acetic acid and predicted using the COSMO-SAC model and the Hansen solubility parameter. The Hansen solubility parameter method predicted a higher solubility of gallic acid in pure water than in pure ethanol, and in a mixed solvent, it predicted the maximum solubility at 80% water content, showing different results from the experimental data trends. However, using the molar volume obtained from COSMO calculations resulted in a tendency that matched the experimental results. The results revealed higher solubility in ethanol compared to water, with the solubility in mixed solvent falling within the range between them. Using the same method, the Hansen solubility parameter obtained was applied to acetic acid/water and acetic acid/ethanol mixtures, and similar trends were observed compared to experimental data. In particular, gallic acid in the acetic acid/water mixture solvent exhibited maximum solubility, and this phenomenon was well-predicted. As the temperature increased, solubility in both pure and mixed solvents also increased. While the COSMO-SAC model effectively captured this trend, the predicted solubility values were slightly lower than the experimental data. The solubility trends depending on solvent types were confirmed by comparing the σ-profiles of each compound. The σ-profile of gallic acid closely resembled that of ethanol, and this result led to higher solubility than water and acetic acid. The maximum solubility in ethanol/water and acetic acid/water mixed solvents could be anticipated when two solvents with significant differences in their σ-profiles are mixed in an appropriate ratio.
]]>Separations doi: 10.3390/separations11010035
Authors: Maja Molnar Dajana Gašo-Sokač Mario Komar Martina Jakovljević Kovač Valentina Bušić
Global food waste has a huge impact on the environment, as it is a source of greenhouse gas emissions and wasted natural resources. Across the world, over 30% of food is lost or wasted each year. Aside from this, the food industry, as well, is one of the biggest sources of agro-industrial waste and by-products, which can be valorized and used for different purposes. Such waste is a good source of bioactive organic compounds that can be extracted without altering their properties, where deep eutectic solvents can serve as green solvents and as an excellent replacement for volatile organic solvents. Isolated compounds can be used in innovative food production, chemical production, cosmetics and other industries. Deep eutectic solvents have attracted extraordinary attention due to their advantages such as environmental friendliness, availability and easy preparation, easy handling and utilization of non-toxic components for their formation. Due to these properties, they are a greener alternative to classic organic solvents for many processes, including extractions. In this paper, we review the utilization of deep eutectic solvents as potential green media for the extraction of organic compounds such as polyphenols, carbohydrates, proteins and alkaloids from by-products of the food industry and from agro-industrial waste.
]]>Separations doi: 10.3390/separations11010034
Authors: Hee-Jung Kim Seo-Hyeon Jung Shokhid Gulyamov Hyun-Gy Lee Oybek Boyjigitov Yong-Moon Lee
Sphingosine 1-phosphate (S1P) is a signaling lipid molecule involved in various cellular processes. It is important to develop a quantitative method for S1P to determine endogenous levels and to investigate its functions. As S1P is a tiny lipid component of most biological samples, highly sensitive analysis by LC-MS/MS is required. The main challenge in S1P analysis by chromatography is peak-broadening due to the presence of a polar phosphate and the fact that S1P is indeed a zwitterion itself. In this study, we used hydrogen fluoride (HF) to efficiently remove a phosphate and then analyzed the surrogate, sphingosine, as a sharp peak by LC-ESI-MS/MS. We optimized the dephosphorylation reaction in terms of temperature and reaction time. Multiple reaction monitoring (MRM) for a dephosphorylated form of S1P and C17-S1P as an internal standard at m/z transition 300.4 > 282.4 (quantification ion), 300.4 > 262.4 (qualification ion), 286.3 > 268.2 (internal standard) was conducted. This method was validated by essential parameters such as specificity, linearity, range, LOQ, LOD, accuracy, precision, and repeatability. To confirm this new method, we quantified S1P levels in various serum products (100.0~284.4 nM). In the sample pretreatment conditions for extracting S1P, the concern about potential sphingosine contamination in serum was negligible. The dephosphorylation efficiency by this method was about two-fold higher than that of alkaline phosphatase (APase). To apply the method in vivo, we analyzed S1P in plasma and kidney tissues obtained from a chronic kidney disease (CKD) mouse model. S1P levels were increased only in CKD kidney tissue but not in plasma. In conclusion, by applying the dephosphorylation step with HF, we established a new, sensitive LC-MS/MS quantitative method for S1P that can be applied to biological samples.
]]>Separations doi: 10.3390/separations11010033
Authors: Yuzhen Bai Aijun Gong Lina Qiu Yiwen Wang Ge Gao Weiyu Zhao Yang Liu Jiayi Yin Xinyu Huang Yiyang Chen
The hot spot extraction agent N,N,N′,N′-tetraoctyl-3-oxoglutaramide (TODGA) has the advantages of novelty, high efficiency and environmental protection in the separation of rare earths by tandem extraction. In this paper, the characteristic parameters for the separation of dysprosium, erbium, thulium and ytterbium ions in the TOGDA–kerosene/hydrochloric acid system for tandem extraction were calculated. Using a 10% TODGA–kerosene/5 mol·L−1 hydrochloric acid extraction system, the mixture containing Dy3+ 0.258 mol·L−1, Er3+ 0.252 mol·L−1, Tm3+ 0.248 mol·L−1 and Yb3+ 0.242 mol·L−1 can be separated by three separation steps, and four products of Dy3+, Er3+, Tm3+ and Yb3+ can be obtained. The purity of the four products was 99.80%, 99.20%, 99.70% and 99.70%, and the yields were 99.03%, 98.97%, 97.88% and 96.98%, in order. In this paper, the reasons were analyzed for the differences in the ability of the TODGA system to extract heavy rare earth ions (REEs) in terms of density functionality, complex structure and bond valence model. These will provide more basic data and guidance for the industrial application of TODGA.
]]>Separations doi: 10.3390/separations11010032
Authors: Gia-Han Tran Neil-Patrick Uy Shi-Heon Kang Wonseok Heo Eun-Song Lee Seong-Soo Roh Sanghyun Lee
Adlay is an annual plant known for its abundant bioactive compounds and diverse pharmacological activities. Coixol, a key component found in various parts of adlay, significantly contributes to its biological activity. This study was conducted to extract adlay sprouts and seeds using different solvents (methanol and ethanol) and extraction methods (reflux and ultrasonic extraction). The extracts were then evaluated for their total polyphenol and flavonoid contents, as well as antioxidant ability (DPPH and ABTS+). Additionally, the coixol content of these extracts was analyzed using HPLC/DAD analysis. The results showed that the extraction methods and solvents used impacted the bioactive compounds and their activities in the samples. Adlay sprouts exhibited a higher compound content and stronger antioxidant capacity than adlay seeds. Moreover, a substantial amount of coixol was found in the sprouts, while it was not detected in the seeds. This study emphasizes the importance of selecting appropriate extraction methods to optimize the biological activities of adlay sprouts and seeds. Adlay sprouts, with their enriched phytochemical compounds and enhanced antioxidant ability, could serve as a valuable material for health product applications.
]]>Separations doi: 10.3390/separations11010031
Authors: Yingchao Mao Lingfeng Zhu Fuhua Fu Lijun Zhu Jiajing Chen Jing Liu Dan Huang Chang Lei
Puerariae Radix is one of the most widely used ancient traditional Chinese medicines and is also consumed as food, which has rich edible and medicinal value. Puerariae Radix can be divided into Puerariae Lobatae Radix (PL) and Puerariae Thomsonii Radix (PT). These two medicinal materials are very similar, and they are often mixed up or misused. In this study, gas chromatography–ion migration spectrometry (GC-IMS) was used to analyze the volatile organic compounds (VOCs) of PL and PT, and the differences in VOCs were analyzed using fingerprint, principal component analysis (PCA), and orthogonal partial least squares discriminant analysis (OPLS-DA). The results showed that a total of 173 VOCs were obtained from PL and PT, and 149 were qualitatively identified, including 38 aldehydes, 22 alcohols, 22 ketones, 19 esters, 13 esters, 10 acids, 10 pyrazines, 6 terpenes, 4 furans, and 2 pyridines. The characteristic VOCs of PL and PT were clarified by constructing GC-IMS fingerprints. PL and PT can be effectively distinguished, and five characteristic VOCs were screened using PCA and OPLS-DA analysis methods. This study identified and evaluated the types and differences in VOCs in PL and PT. The established method is simple, rapid, accurate, and sensitive, and it provides theoretical guidance for the identification, tracing, and quality evaluation of PL and PT.
]]>Separations doi: 10.3390/separations11010030
Authors: Maria Nieddu Valeria Pasciu Maria Piera Demontis Elena Baralla
Sunscreens are topical preparations containing one or more compounds that protect humans from ultraviolet (UV) light. This review focuses on analytical methods, particularly liquid chromatography, with the aim of identifying and determining UV filters (UVFs) in environmental and marine biota matrices. A literature review was conducted using NIH (PubMed and Medline), FDA and EPA databases, Google Scholar, and federal regulations. This retrospective literature review is focused on the last five years. UVF quantification in environmental and biological matrices showed a wide array of methods where liquid chromatography is predominant. The scientific literature identified a large variety of analytical methodologies that are compared in this review to evaluate the better results in terms of limits of quantification and the possibility to identify as many analytes as possible simultaneously.
]]>Separations doi: 10.3390/separations11010029
Authors: Xiaoyu Xu Jiahua Liu Yuang Cao Han Wang Keqiang Zhang Chein-Chi Chang Suli Zhi
This study tried to use electroflocculating precipitated waste to prepare a Si@Al adsorbent by simply mixing sodium silicate at a mass ratio of 4:1 and calcining at 200 °C for 2 h. The adsorbent was low cost, high efficiency, and could remove a variety of contaminants (organic pollutants, antibiotics, and metal ions) from water. In this study, adsorbent characterization and pollutant adsorption experiments were carried out. The results showed that: Si@Al adsorbent had uniform particles, distinct layers, a loose porous appearance, and the internal structure was scattered without a crystal structure. The optimal adsorption conditions for tetracycline were as follows: dosage of adsorbent 2.0 g/L, reaction time 10 min, pH = 4.5, and tetracycline removal rate of 97.13%. The optimal adsorption conditions for MB (MB stands for methylene blue) were an adsorption dosage of 4.0 g/L, a reaction time of 15 min, pH = 4.5–8.5, and a removal rate of 96.39%. The optimal adsorption conditions for Cu were a 2.0 g/L dosage of adsorbent, a reaction time of 30 min, a pH of 8.5, and a highest removal rate of 97.47%. It was worth noting that the effect of temperature on TC, MB and Cu was not significant. At the same time, the kinetic fitting results showed that the adsorption of MB was more consistent with the quasi-second-order kinetic model, with R2 ranging from 0.9788 to 1.0000. The adsorption of TC and Cu was more consistent with the quasi-first-order kinetic model, with R2 ranging from 0.9598 to 0.9999 and 0.9844 to 0.9988, respectively. According to the results of thermodynamics, kinetics and zero potential point, the adsorption of tetracycline and methylene blue was mainly a physical adsorption, multilayer heterogeneous or single-layer homogeneous adsorption process. The adsorption of Cu was categorized as multi-layer heterogeneous chemical adsorption. The co-existing substances had little effect on the properties of the adsorbent, and the adsorbent could be recycled 5 times. Compared with other adsorbents, the results showed that the adsorbents had obvious advantages in terms of the raw material source, preparation method, time cost and removal effect. This study provided a “waste into treasure, green and efficient” multi-pollutant adsorption method.
]]>Separations doi: 10.3390/separations11010028
Authors: Thomas Senfter Igor Schweiggl Manuel Berger Christian Mayerl Tobias Kofler Michael Kraxner Axel Steffens Martin Pillei
The dewatering of substrates is one of the key tasks in the handling of material flows in a circular economy. Besides belt filters, sedimenters, and decanters, screw presses are frequently used to reduce the water content of substrates. However, screw presses available on the market are usually designed for high throughputs (>5 m3/h). The dewatering of smaller feed rates (<1 m3/h), however, requires more compact solutions. For this reason, a compact screw press (short screw length), which is normally used in agriculture for cow manure dewatering, was investigated in this work, as there exist no publications on this type of compact screw press. A mobile test setup was developed and loaded with different material such as digested sludge from a wastewater treatment plant, commercially available potting soil, wood shavings, and biological waste. The dry matter content of the feed material, the feed material itself, the screw rotational speed, and the weight setting (pressure) at the back plate were varied, and the effects on the dewatering result were recorded. A significant influence on the dewatering result was found for the weight setting, the type of substrate (particle size), and the dry substance content of the feed material. The tests confirmed that the compact screw press separator is suitable for the dewatering of wood shavings and biological waste (with an increase in dry matter percentage of up to 7.7%). The direct dewatering of potting soil and digested sludge is not possible and can only be implemented by using structural support material. This study fills the gap between published work on large screw presses and potentially new application fields of compact screw press manure separators, which, until now, have only been used in agriculture.
]]>Separations doi: 10.3390/separations11010027
Authors: Antao Gao Nina Nouri Keisean Stevenson Edith T. Zemanick Jerry A. Nick Jane E. Hill
Headspace solid-phase micro-extraction (HS-SPME) is a prevalent technique in metabolomics and volatolomics research. However, the performance of HS-SPME can vary considerably depending on the sample matrix. As a result, fine-tuning the parameters for each specific sample matrix is crucial to maximize extraction efficacy. In this context, we conducted comprehensive HS-SPME optimization for bronchoalveolar lavage fluid (BALF) samples using two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-ToFMS). Our exploration spanned several HS-SPME parameters, including vial size, dilution factor, extraction time, extraction temperature, and ionic strength. The 10 mL vial size, no sample dilution, extraction time of 50 min, extraction temperature of 45 °C, and 40% salt were identified as the optimized parameters. The optimized method was then evaluated by a pair-wise comparison of ten sets of samples. The results revealed that the optimized method yielded an increase of 340% in total peak area and an increase of 80% in total peak number. Moreover, enhancements were observed across nine major chemical classes in both peak area and number. Notably, the optimized method also doubled the number of volatile compounds consistently detected across BALF samples, from 52 to 108.
]]>Separations doi: 10.3390/separations11010026
Authors: Huapeng Liu Xiyuan Wang Youqian Zhai Tingting Xu
Because of the requirements for accelerating the construction of a green, low-carbon, and recycling economy development system, the petrochemical industry has been paying attention to green and low-carbon transformations and innovations. Oily sludge is a type of bulk hazardous solid waste from various sources that significantly harms the environment. Chemical heat washing of oily sludge represents a large proportion of the treatment technology for oily sludge, which can be used individually and has many applications in joint treatment with other processes. However, research on the formulation of cleaning agents for this process has mainly focused on the surfactant at this stage, and many studies have demonstrated the secondary pollution of surfactant; thus, research on reducing or replacing surfactants as cleaning agents has been conducted. This review highlights the research progress of chemical heat washing of oily sludge according to the classification of cleaning agents and describes the reasons for the stabilization of currently recognized oily sludge, the chemical heat washing process, and the mechanism of oil–soil separation. Finally, the research direction for new emulsions as new cleaning agents to replace surfactants is set out.
]]>Separations doi: 10.3390/separations11010024
Authors: Michiel Nijboer Asif Jan Mingliang Chen Kevin Batenburg Julia Peper Tom Aarnink Fred Roozeboom Alexey Kovalgin Arian Nijmeijer Mieke Luiten-Olieman
Atomic layer deposition (ALD) is known for its unparalleled control over layer thickness and 3D conformality and could be the future technique of choice to tailor the pore size of ceramic nanofiltration membranes. However, a major challenge in tuning and functionalizing a multichannel ceramic membrane is posed by its large internal pore volume, which needs to be evacuated during ALD cycling. This may require significant energy and processing time. This study presents a new reactor design, operating at atmospheric pressure, that is able to deposit thin layers in the pores of ceramic membranes. In this design, the reactor wall is formed by the industrial tubular ceramic membrane itself, and carrier gas flows are employed to transport the precursor and co-reactant vapors to the reactive surface groups present on the membrane surface. The layer growth for atmospheric-pressure ALD in this case proceeds similarly to that for state-of-the-art vacuum-based ALD. Moreover, for membrane preparation, this new reactor design has three advantages: (i) monolayers are deposited only at the outer pore mouths rather than in the entire bulk of the porous membrane substrate, resulting in reduced flow resistances for liquid permeation; (ii) an in-line gas permeation method was developed to follow the layer growth in the pores during the deposition process, allowing more precise control over the finished membrane; and (iii) expensive vacuum components and cleanroom environment are eliminated. This opens up a new avenue for ceramic membrane development with nano-scale precision using ALD at atmospheric pressure.
]]>Separations doi: 10.3390/separations11010025
Authors: Nicoletta De Vietro Antonella Maria Aresta Jennifer Gubitosa Vito Rizzi Carlo Zambonin
Phthalates are the synthetic chemical plasticizers with the most varied uses and are a source of concern due to their toxicity and ubiquity, so much so that even plasticizer-free polymers can contain them as non-intentionally added substances (NIAS). Food packaging is among the materials with the greatest impact. In this study, a simple protocol is proposed for the location and identification of dimethyl phthalate, diethyl phthalate, dipropyl phthalate, and dibutyl phthalate which is applicable to compliance studies of food packaging materials and for the associated risk assessment. Solid phase microextraction gas chromatography/mass spectrometry was used to evaluate the migration of four NIAS from food packaging to release media simulating food substrates. Three plasticizer-free polymers were used: two that were lab-made and based on sodium alginate and a commercial polyethylene film. Linearity ranged from the LOQ to 10 µg/mL; within-day and between-day precision values were between 12.3–25.7% and 21.9–35.8%, respectively; the LOD and LOQ were in the range 0.029–0.073 µg/mL and 0.122–0.970 µg/mL. Migration tests were conducted for different periods of time at room temperature and at 8 °C. Exposure to microwaves (MW) was also evaluated. All packaging materials tested had global migration limits lower than 10 mg/dm2 of material surface.
]]>Separations doi: 10.3390/separations11010023
Authors: Andrea Mariela Araya-Sibaja Felipe Vargas-Huertas Silvia Quesada Gabriela Azofeifa José Roberto Vega-Baudrit Mirtha Navarro-Hoyos
The biological activities of curcuminoids, the main polyphenol constituents of Curcuma longa (turmeric), have been the subject of many studies in recent years. However, these studies have focused on the major active compound, curcumin (CUR), while other important constituents, demethoxycurcumin (DMC) and bisdemethoxycurcumin (BDM) have been less studied and reported in the literature regarding their bioactivity as well as their isolation and solid-state characterization. Hence, in this study, DMC and BDM were isolated using pressurized liquid extraction (PLE) followed by column chromatography and crystallization. HRMS and 1H and 13C NMR were used to characterize them. Solid-state characterization was performed through powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM) techniques. Further, powder dissolution profiles were performed in two media, antioxidant and cytotoxic activities were determined through 2,2-diphenyl-1-picrylhidrazyl (DPPH) and an MTT assay on gastric adenocarcinoma (AGS), colorectal adenocarcinoma (SW-620), and hepatocellular carcinoma (HepG2) cell lines. DMC and BDM were extracted from Curcuma longa cultivated in Costa Rica, using pressurized liquid extraction (PLE), then isolated and purified, combining column chromatography and crystallization techniques. The highly pure solids obtained were shown to be crystalline with an amorphous component. Although the PXRD pattern of BDM suggested a high amorphous component, the crystal exhibited a well-defined and faceted shape. Meanwhile, DMC crystallized in a botryoidal habit, and this constitutes the first report for this compound. On the other hand, BDM was slightly more soluble than DMC, which in turn showed an antioxidant IC50 value 28% higher than BDM (12.46 and 17.94 µg/mL, respectively). In respect to the cytotoxic effects, DMC showed a better IC50 value than BDM for both the SW-620 and AGS cell lines, while BDM exhibited a better IC50 value than DMC against the HepG2 cell line (64.7 μM). In terms of selectivity, BDM and DMC had the highest SI value for SW-620 cells compared to non-tumoral cells, while both compounds also displayed the best cytotoxic effect against these colon adenocarcinoma SW-620 cells, indicating BDM and DMC as potential chemotherapeutic drugs.
]]>Separations doi: 10.3390/separations11010022
Authors: Claudia Venditti Gert Desmet Alessandra Adrover
We investigate band broadening in the most widely adopted configuration of micro-pillar array columns (μPACs)—specifically, a cylindrical pillar array where both the pillar walls and the channel bottom are coated with a thin layer of mesoporous material. The two-zone moment analysis method is adopted to investigate the dispersion properties of μPACs in a broad range of shell thicknesses, reduced fluid velocities, and retention factors. Three different models of the unit cell, of increasing complexity, have been implemented, namely a two-dimensional model and two different three-dimensional models with and without the retentive bottom layer, the presence of which seems to have a very significant effect on the plate height curves. Model predictions are compared with experimental van Deemter curves for uncoated and coated porous layers, and a robust relationship between the intra-particle (porous-zone) diffusion coefficient Dpz and the retention factor k′ is established.
]]>Separations doi: 10.3390/separations11010021
Authors: Bogusław Buszewski Dušan Berek Virginia Coman
The origin of the International Symposia on Separation Sciences (ISSS) can be found in the national gas chromatography scientific meetings held in Zagreb, Croatia, from 1967 and later at Plitvice Lakes until 1988 [...]
]]>Separations doi: 10.3390/separations11010020
Authors: Wenxia Xie Chunmin Tu Jun Zhang Chengwei Xu
The accumulation of uncollected fly ash from flue gas in post-combustion CO2 capture processes is a significant concern in current coal-fired power plants due to its potential impact on the performance of CO2 absorbent and absorption towers. In order to determine the effect of fly ash on the mass transfer performance of CO2 absorption into monoethanolamine (MEA) and diethanolamine (DEA) aqueous solutions, experimental studies were carried out using a small-sized packed tower equipped with θ-ring random packing. These studies were conducted under various operating parameters, including solution temperature, liquid/gas ratio (L/G), packing height, and fly ash concentration. The results show that the effect of fly ash on the outlet CO2 concentration was primarily observed during the initial stages of the experimental process. Moreover, the presence of fly ash leads to a reduction in the volumetric overall mass transfer coefficient (KGav) when using MEA and DEA solution, and increasing the fly ash concentration further exacerbates this negative impact. However, the effect of fly ash on the reduction in KGav is not significantly related to its chemical composition but rather depends on the operational parameters. With increasing solution temperature, liquid/gas ratio (L/G), and packing height, the KGav values for different solutions exhibit an upward trend. The negative effect of fly ash on KGav remains relatively stable for MEA as solution temperature and packing height increase. Compared to MEA, fly ash has a greater negative effect on DEA solution under the same experimental conditions. The analysis reveals that the detrimental effect of fly ash on KGav primarily stems from its ability to alter the distribution state of the absorption liquid within the packed tower.
]]>Separations doi: 10.3390/separations11010019
Authors: Ikki Tateishi Mai Furukawa Hideyuki Katsumata Satoshi Kaneco
B-doped zinc oxide/copper oxide composites prepared using a simple method showed high photocatalytic hydrogen production activity in the presence of aqueous sulfide solutions. Co-modification of the CuO composite with B-doping caused an increase in the charge separation efficiency and light absorption capacity. The sacrificial effect was thermodynamically enhanced by manipulating the composition of the sulfide solution. A maximum hydrogen production activity of 224 μmol g−1 h−1 was achieved under 450 nm light irradiation in a photocatalytic system with optimized B doping, a CuO composite, and a sulfide sacrificial agent concentration.
]]>Separations doi: 10.3390/separations11010018
Authors: Mohamed A. Abdelaziz Neil D. Danielson
In this work, three cyanoalkyl silicone GC stationary-phase polymers, namely OV-105, OV-225, and OV-275, were investigated as potential extractants for dispersive liquid–liquid microextraction (DLLME). The OV-225 polymer (cyanopropylmethyl-phenylmethylsilicone) exhibited the cleanest chromatographic background and was extensively studied. The proposed polymer was tested through the DLLME of four non-steroidal anti-inflammatory drugs from aqueous samples, followed by HPLC separation with UV detection at 230 nm. To achieve the maximum enrichment, the experimental conditions that influence the DLLME process were optimized using one-factor-at-a-time and design-of-experiment (DoE) approaches. The extraction variables (polymer mass, dispersive solvent volume, buffer pH, and mixing time) were screened by implementing a two-level full factorial design (FFD). Significant variables were fine-tuned using response surface methodology based on a face-centered central composite design (CCD). The optimum conditions were 10 mg of polymer (extraction medium); 50 µL of tetrahydrofuran (dispersive solvent); 100 µL of phosphate buffer pH 2.75 ([PO43−] = 100 mM); and 3 min of vortex mixing. The addition of salt had a minimal effect on the enrichment factors. In the optimum conditions, enrichment factors up to 46 were achieved using 1.5 mL samples. Calibration curves exhibited correlation coefficients > 0.999 using 4-pentylbenzoic acid as an internal standard. The limits of quantitation were 5 ng/mL for naproxen, 10 ng/mL for diflunisal, 25 ng/mL for indomethacin, and 75 ng/mL for ibuprofen. The analysis of spiked tap water samples showed adequate relative recoveries and precision. In conclusion, the proposed polymer (OV-225) is a potential greener alternative to traditional organic extractants used in DLLME.
]]>Separations doi: 10.3390/separations11010017
Authors: Tao Bai Yuhu Yao Jiaxin Zhao Laixin Tian Luming Zhang
This study investigated the adsorption performance of hydrothermal carbon derived from banana peel and modified with different concentrations of phosphoric acid solution, then used to adsorb lead ions in an aqueous solution. The surface structure and functional groups of the modified hydrothermal carbon were analyzed using XRD, SEM, FT-IR, elemental analysis, and BET. The results showed that the adsorption capacity of modified hydrothermal carbon derived from banana peel reached 40.64 mg/g at a hydrothermal temperature of 240 °C, a phosphoric acid solution of 2 mol/L, and a solid–liquid ratio of 2 g/L, with a removal efficiency of 82.74%. The adsorption process conformed to the pseudo-second-order kinetic model and the Langmuir isotherm equation. The correlation coefficient of 0.99 for fitting the adsorption process using an artificial neural network, indicating that the artificial neural network could be used to predict adsorption. The adsorption of Pb(II) from an aqueous solution by phosphoric acid-modified hydrothermal carbon was dominated by monolayer chemical adsorption, and the adsorption mechanisms included electrostatic attraction, ion exchange, surface complexation, and physical adsorption.
]]>Separations doi: 10.3390/separations11010016
Authors: Felix Buthmann Sophia Volpert Jörg Koop Gerhard Schembecker
Centrifugal Partition Chromatography (CPC) utilizes a two-phase liquid–liquid system as mobile and stationary phases. During operation, the latter continuously drains out of the rotor, despite it being in fact stationary, leading to decreasing separation efficiency over time, a phenomenon still poorly understood today because neither simulations nor extensive experimental investigations have addressed this so-called bleeding. With the model presented in this study, the underlying hydrodynamics are discussed in detail. This model can simulate bleeding over 60 s and is verified experimentally for different operating points (volumetric flow rates of 5, 12, and 20 mL⋅min−1) of the Centrifugal Partition Chromatograph utilizing an aqueous–organic phase system. We simulated two interconnected chambers at the rotor inlet and analyzed the loss of the stationary phase over time. The results of the simulated second chamber are closely aligned with the experimental validation results. Thus, the prediction of bleeding utilizing the simulation of hydrodynamics was successful. Moreover, we highlighted the benefits of the two-chamber setup modeled in this study compared to single-chamber models.
]]>Separations doi: 10.3390/separations11010015
Authors: Antonio Francioso Ignacio Antonio Jiménez Díaz Carolina Pérez Reyes Cristina González Montelongo Marco Pierini Claudio Villani Isabel López Bazzocchi
Phyllanthus is a large genus of the Euphorbiaceae family, which has been widely used in traditional medicine. The current study reports the isolation of an unusual C-glycosyl flavonoid, named tenelloside, from Phyllanthus tenellus Roxb., a non-endemic plant present in Canary Islands. The chemical structure of this secondary metabolite was established employing combined spectrometric and spectroscopic techniques, including 1D and 2D NMR experiments and mass spectrometry. The absolute stereochemical configuration was determined via the comparison of experimental and calculated electronic circular dichroism spectra. In our previous work, another C-glycosylated bioactive product was isolated from another Phyllanthus species, suggesting that this class of compounds can be produced in a genus-specific manner in different geographic regions. This work represents another important report for direct future studies on the biological and chemotaxonomic potential of C-glycosylated products of the Phyllanthus genus.
]]>Separations doi: 10.3390/separations11010014
Authors: Ljuboš Ušjak Marjan Niketić Silvana Petrović
The aim of this work was to investigate the composition of essential oils isolated from fruits of Peucedanum longifolium, and Rhizomatophora aegopodioides (a species which was previously placed in the genus Peucedanum), as well as to compare the obtained results to those available for other previously investigated related species (including taxa which are also, according to some authors, excluded from the genus Peucedanum). Essential oils were obtained via hydrodistillation in a Clevenger-type apparatus and their composition was analyzed using GC-FID and GC-MS. To compare these data to those of previously investigated taxa, a chemometric approach was applied; the data were analyzed using multivariate statistical methods: non-metric multidimensional scaling (nMDS) and hierarchical cluster analysis. The most abundant in P. longifolium essential oil were monoterpenes (79.7%), mostly α-phellandrene (26.2%), β-phellandrene + limonene (21.0%) and myrcene (9.5%), followed by sesquiterpenes (18.3%), mostly germacrene B (9.5%). On the other hand, dominant in R. aegopodioides essential oil were non-terpenic aliphatic hydrocarbons (46.1%), mainly n-undecane (16.5%) and n-nonane (11.3%). In addition, this essential oil also contained a notable quantity of sesquiterpenes (25.1%), with (E)-sesquilavandulol being the most abundant (10.0%). The results of multivariate statistics revealed a clear separation of the essential oil composition of R. aegopodioides and P. longifolium, as well as of P. longifolium and P. officinale. The clustering of the samples of most of the taxa that do not belong to the Peucedanum in the narrow sense (sensu stricto) was also observed, which is in accordance with their recent inclusion in separate genera.
]]>Separations doi: 10.3390/separations11010013
Authors: Tellez-Robles Daniela López-Cortez Ma. del Socorro Santoyo-Tepole Fortunata Rosales-Martínez Patricia García-Ochoa Felipe Hernández-Botello Mayuric Teresa Salgdo-Cruz María de la Paz
Red wine contains polyphenols which are extracted during the winemaking process. However, winemaking is not an extraction; therefore, the resulting byproducts still have a substantial polyphenol content. The aim of this study was to compare two methods for the extraction of phenolic compounds: maceration and matrix solid-phase dispersion (MSPD). Grape pomace (Vitis vinifera var. Cabernet Sauvignon) from a winery in Querétaro, Mexico was used. The optimal conditions for both methods were identified. Phenolic compounds and antioxidant activity were the response variables. A central composite design was used (Minitab 17) for the extraction by maceration. The maceration time (1, 4, 12, 20, and 24 h) and the ratio of ethanol (50 to 80%) acidified with 1% HCl were the two factors studied. For the MSPD extraction, sea sand was used as a dispersant, and a 22 factorial design was employed for the evaluation, with the elution volume and the ratio of sample/dispersant being the two factors analyzed. The optimal extraction method was MSPD with 96 mL (acidified ethanol) as the elution volume and a 1:2 ratio of sample/dispersant. Using these conditions, 14.01 ± 0.19 mMol TEAC/100 g db (Trolox equivalent of antioxidant capacity) of grape pomace was obtained, whereas the total phenolic content was 2836.73 ± 41.90 mg GAE/100 g db. These values are greater than those obtained by maceration. These conditions are close to those predicted by the model (analysis of variance (ANOVA) with a level of significance of 5% (p < 0.05) and a Tukey comparison test for determining significant differences in the comparison of results).
]]>Separations doi: 10.3390/separations11010012
Authors: Rodrigo Martorelli Galera Adrielli Cristina Peres da Silva Alexandre de Oliveira Jorgetto Marcos Henrique Pereira Wondracek Margarida Juri Saeki José Fabián Schneider Valber de Albuquerque Pedrosa Marco Autônio Utrera Martines Gustavo Rocha Castro
Using straightforward and cost-effective methods, persimmon leaves were converted into high-quality powder. This powder was applied as an adsorbent for the removal of Cu(II) and Cd(II) from aqueous solutions. Scanning electron microscopy (SEM) revealed the presence of particles with non-homogeneous sizes and rough textures. The biosorbent exhibited a specific surface area of approximately 0.44 ± 0.015 m2 g−1. Elemental analysis and energy-dispersive X-ray spectroscopy (EDX) confirmed the presence of elements such as sulfur, phosphorus, nitrogen, and oxygen. The results of 13C nuclear magnetic resonance (13C-NMR), obtained using the cross-polarization technique, show the presence of groups containing sulfur and oxygen. Infrared spectroscopy (FTIR) indicated the existence of amine and hydroxyl groups. The material was used in the solid-phase extraction of Cu(II) and Cd(II) in batch experiments, and its adsorption capacity was evaluated as a function of time, pH, and analyte concentration. The fraction with a diameter between 63 and 106 μm was selected for the adsorption tests. Kinetic equilibrium was reached within 5 min, and the experimental data were fitted to the pseudo-second-order kinetic model. The optimum pH for the adsorption of both metal species was approximately 5.0. The adsorption isotherms were adjusted using the modified Langmuir equation, and the maximum amount of metal species extracted from the solution was determined to be 0.213 mmol g−1 for Cu(II) and 0.215 mmol g−1 for Cd(II), with high linear correlation coefficients for both metals. Persimmon leaves are typically abundant during the growing season, and because they are seasonal, the Diospyros kaki L.f. tree undergoes the natural process of leaf abscission, ensuring the availability of leaves for application.
]]>Separations doi: 10.3390/separations11010011
Authors: Merrik Kobarfard Tadeusz Górecki
Sulfolane, a highly water-soluble industrial solvent, has raised environmental concerns due to its widespread usage and its prolonged persistence once released into the environment. To assess the extent of contamination effectively, reliable analytical methods are essential. In this review article, the existing methodologies for the sample preparation and determination of sulfolane are systematically examined and evaluated. In brief, existing guidelines for sampling from environmental matrices provide a solid foundation for sulfolane analysis. Notably, there is little variation in the choice of final determination methods, with GC-MS or GC-FID being favored across all studies. However, substantial variability emerges in sample preparation methods. Moreover, upon scrutiny of the analytical procedures utilized in sulfolane analysis, it becomes evident that a considerable number of them are characterized by inefficiency or environmental hazards, often relying on substantial quantities of chlorinated solvents. Through this review, valuable insights into the challenges at hand and potential solutions can be gained, offering a foundation for the development of novel sulfolane analysis methods applicable to a range of environmental matrices. Overall, this field calls for further research to devise efficient and environmentally sustainable analytical methods for sulfolane analysis.
]]>Separations doi: 10.3390/separations11010010
Authors: Manal El-Gendy Mohamed Hefnawy Adeeba Alzamil Adel El-Azab Alaa Abdel-Aziz Ali El Gamal
A novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the simultaneous determination of tipiracil (TIP), trifluridine (FTD), and their metabolites, 5-trifluoromethyluracil (FTY) and 5-carboxy-2′-deoxyuridine (5CDU), in rat plasma. This method is highly sensitive, specific, and fast. Paracetamol (PAR) is used as an internal standard (IS). Using acetonitrile-induced protein precipitation, the analytes were extracted from a plasma sample and separated on a Waters BEH C18 (1.7 μm particle size, 50 mm × 2.1 mm ID) column protected by a security guard cartridge (C18, 4 × 2.0 mm). The isocratic mobile phase was made up of methanol and water containing 0.1% formic acid (80:20, v/v) at a flow rate of 0.5 mL/min for 4 min. The quantification was performed using a positive electrospray ionization (ESI) interface and a multiple-reaction monitoring (MRM) mode. The MRM transitions employed were m/z 242.96 → 182.88 for TIP, 296.96 → 116.86 for FTD, 180.98 → 139.85 for FTY, 272.96 → 156.86 for 5CDU, and 151.97 → 92.68 for IS. The validated method complied with the guidelines set by the US-FDA over on a linear concentration range of 5–4000 ng/mL for FTD, FTY, and 5CDU, and 5–1000 ng/mL for TIP. The coefficient of determination (r2) was equal to or greater than 0.997. The corresponding lower limits of detection (LLOD) were 1.5 ng/mL for FTD, FTY, and 5CDU and 1.0 ng/mL for TIP. The recoveries of all analytes from rat plasma ranged from 88.67% to 112.18%, and the mean relative standard deviation (RSD) of accuracy and precision result was less than or equal to 6.84%. FTD, FTY, 5CDU, and TIP demonstrated adequate stability throughout the various circumstances examined. Additionally, no matrix effects were identified for any of the analytes. The assay was effectively utilized to conduct a pharmacokinetic study in rats following the oral administration of FTD and TIP at a dosage of 5.6 mg/kg, with a ratio of 1:0.5 for FTD and TIP, respectively. This indicates that the suggested approach is suitable for future clinical research. The pharmacokinetic parameters Cmax (maximum concentration), Tmax (time to reach maximum concentration), t1/2 (half-life), AUC0-24 (area under the concentration–time curve from 0 to 24 h), AUC total (total area under the concentration–time curve), Ke (elimination rate constant), Vd (volume of distribution), and CL (clearance) of all analytes were assessed. The assay developed exhibits significant advancements compared to earlier bioanalytical methods documented in the literature. These improvements include high sensitivity, specificity, and efficacy in high throughput analysis of complex matrices. Additionally, the assay offers a shorter run time and smaller sample volume (50 μL).
]]>Separations doi: 10.3390/separations11010009
Authors: Pavlina Kousi Dimitra-Artemis Strongyli Petros E. Tsakiridis Artin Hatzikioseyian Emmanouella Remoundaki
This work presents a biological remediation process for molybdenum-bearing wastewater which may lead to the fabrication of biogenic Mo chalcogenide particles with (photo)catalytic properties. The process is based on dissimilatory sulphate reduction, utilising sulphate-reducing bacteria (SRB), and reductive precipitation of molybdate which is the predominant species of molybdenum in oxygenated water/wastewater. The SRB culture was established in a biofilm reactor which was fed with synthetic solutions containing sulphate (17.7 mM), molybdate molybdenum (2 mM), divalent iron (1.7 mM) and ethanol as the carbon/electron donor. The performance of the bioreactor was monitored in terms of pH, sulphate and molybdenum (Mo(VI) and total) content. The presence of thiomolybdate species was studied by scanning UV-Vis absorbance of samples from the reactor outflow while the reactor precipitates were studied via electron microscopy coupled with energy dispersive spectrometry, X-ray diffractometry and laser light scattering. A molar molybdate/sulphate ratio of 1:12.5 proved effective for molybdate reduction and recovery by 76% in 96 h, whereas sulphate was reduced by 57%. Molybdenum was immobilised in the sulphidic precipitates of the bioreactor, presumably via two principal mechanisms: (i) microbially mediated reduction and precipitation, and (ii) thiomolybdate formation and sorption/incorporation into iron sulphides.
]]>Separations doi: 10.3390/separations11010008
Authors: Sebnem Kurhan Kateřina Hanková Pavel Klouček Martin Koudela
Straw is an important by-product of crop production. It has been widely used as a feed as well as in fruit–vegetable production due to exerting a positive impact on soil and crop health and quality in the operated areas. On the other hand, applied crop-specific herbicides throughout the production stage, like aminopyralid (AP), may lead to significant plant injuries in sensitive vegetable plantations, even in very low concentrations. This study aims to optimize a short time, minimal consumables needed, and sensitive extraction and analytical method for AP residues in straw material using LC-MS/MS. For this purpose, standard AP signal response in acetonitrile (MeCN) and 1% of formic acid (FA) in methanol (MeOH) were tested; several chromatographic separation and mass spectroscopy (MS) parameters were improved and optimized. Subsequently, two different extraction methods were performed in AP spiked straw samples, and extraction efficacies were compared. Salting-out assisted liquid–liquid extraction (SALLE) by acidified MeCN combined with final dissolution in MeOH with 1% of FA prior to the analysis was chosen as the most appropriate method for the straw matrix. This method was then used for validation and real sample test analysis. The limit of quantification (LOQ) of AP in this optimized extraction method achieved 10 ng/g straw with a recovery rate of 71% and 13% RSD. The method was also tested on field straw mulch samples and 22.54 ± 0.8 ng/g of AP was detected.
]]>Separations doi: 10.3390/separations11010007
Authors: Wei Jiang Jilai Xue Kaixi Jiang Xunxiong Jiang Shengdong Wang Jinping Hu Derek O. Northwood Kristian E. Waters Hao Ma
Sulfuric acid curing and leaching is a promising technology for treating refractory ores. In this work, a refractory concentrate containing 3191 ppm uranium (U), 2135 ppm niobium (Nb), and 0.7% rare earth minerals (REMs) went through two stages: curing by high-concentration H2SO4 and leaching by low-concentration H2SO4. We investigated the behavior of those valuable metals during the two stages. For both curing and leaching, the operating parameters include the acid-to-solid ratio, time, temperature, and H2SO4 concentration. The recovery for U, Nb, and REMs was as high as 95%, 86%, and 73.5% using a curing acid-to-solid ratio of 1:1, curing temperature of 200 °C, curing time of 1 h, H2SO4 concentration of 98%, leaching liquid-to-solid ratio of 4:1, leaching time of 2 h, leaching temperature of 60 °C, and leaching H2SO4 concentration of 5 g/L. A “sulfuric acid curing–leaching-U extraction by N235–Nb recovery by resin adsorption–REMs’ recovery by resin adsorption” method was implemented, where the overall U, Nb, and REMs’ recovery reached 93.1%, 84.5%, and 69.6%, respectively.
]]>Separations doi: 10.3390/separations11010006
Authors: Mehedi Hasan La Hoang Anh Tran Dang Xuan
This is the first study aiming to enrich momilactones A (MA) and B (MB) and phenolic compounds in germinated brown rice (GBR) and non-GBR var. Koshihikari and Milky Queen through the cooking process. Extraction methods for these compounds were optimized by applying various conditions, including solvents (80% methanol and 80% ethanol), heat (80 °C), and sonication (2 h). Momilactone and phenolic quantities were determined by ultra-performance liquid chromatography–electrospray ionization mass spectrometry (UPLC–ESI-MS) and high-performance liquid chromatography (HPLC), respectively. Accordingly, cooked Koshihikari GBR extract using 80% methanol and sonication (GKB4) revealed the highest amounts of tricin, caffeic, ρ-hydroxybenzoic, ρ-coumaric, ferulic, salicylic, and cinnamic acids (1.71, 1.01, 0.62, 0.45, 0.94, 2.50, and 0.37 mg/g DW, respectively), consistent with the strongest antiradical activities in DPPH and ABTS assays (IC50 = 1.47 and 1.70 mg/mL, respectively). Non-cooked GBR Koshihikari extract using 80% ethanol and sonication (GKB9) exhibited the highest MA and MB contents (147.73 and 118.8 μg/g DW, respectively). Notably, GKB9 showed potent inhibition of α-amylase and α-glucosidase (IC50 = 0.48 and 0.15 mg/mL, respectively), compared with the anti-diabetic drug acarbose (IC50 = 0.26 and 2.48 mg/mL, respectively). The findings hold significant implications for developing phenolic- and momilactone-enriched brown rice with health-beneficial properties.
]]>Separations doi: 10.3390/separations11010005
Authors: Monica Moroni
In recent decades, the versatility of fossil-based polymers has led them to become one of the most used materials for the production of several consumer goods. The destiny of post-consumer plastics is crucial for environmental sustainability. Two are the alternatives to landfilling: (i) energy recovery, i.e., replacement of traditional fuel with plastic litter, and (ii) recycling, i.e., processing of plastic wastes to produce secondary raw materials that may substitute primary raw materials. This work presents the investigation of a device for the hydraulic separation of heterogeneous plastic wastes, which, when properly upscaled, may be efficiently used within recycling plants. This apparatus is suitable for the separation of granules or flakes of plastics with a density higher than 1000 Kg/m3 and may replace existing technologies for mechanical recycling. The purpose of the device is to separate the useful fraction from a mixture of plastics and water introduced inside. The separation procedure efficacy relies on the difference in density, dimension, and shape of the processed plastic particles and on the flow features within the device. Experiments were carried out to test the efficacy of the device as a function of those factors. To increase the range of variation in the key parameters influencing the apparatus’s working principles, Computational Fluid Dynamics was employed to build a numerical model of the device. The validated numerical model suitable to fully characterize the apparatus performance features a hybrid grid with an inner mesh of 3·10−3 m size, a careful modeling of the near-wall region, and the k-ω SST turbulent model.
]]>Separations doi: 10.3390/separations11010004
Authors: Tianyang Hao Lingyang Fan Yiyue Chang Hui Yang Kai He
Myrica rubra (Lour.) Siebold & Zucc bark is a traditional natural medicine used by the people of the Dong minority in western Hunan in China. In this study, the main compounds in Myrica rubra bark including epigallocatechin gallate, myricetrin, myricetin, taraxerol, myricanol, and 11-O-acetylmyricanol were separated using both silica gel column chromatography and high-speed countercurrent chromatography (HSCCC). Notably, it is the first report of discovering 11-O-acetylmyricanol from Myrica rubra bark. The results of the bioactivity studies suggested that epigallocatechin gallate showed the highest α-glucosidase inhibitory activity, while myricetin exhibited the highest reactive oxygen species (ROS) scavenging ability in zebrafish embryos. Intriguingly, myricanol exhibited strong apoptosis-inducing activity on HepG2 cells, and further studies revealed that myricanol was capable of promoting the cleavage of caspase 3, 8, and 9, then resulting in the apoptosis in HepG2 cells. The findings of the present study have important implications for the separation of the main compounds in Myrica rubra and will provide credence to the ethnomedicinal application of the isolated compounds against cardiovascular disease and cancer.
]]>Separations doi: 10.3390/separations11010003
Authors: Qingqing Li Ying Li Huazhou Niu Enhui Wang Lili Jiao Hui Li Wei Wu
Polysaccharides are the main nutritional constituents in the Armillaria mellea fruiting bodies. The structure and immunoactivity of Armillaria mellea polysaccharide are valuable to be determined for development. In the present study, two polysaccharides, including Armillaria mellea neutral polysaccharide (AMPN) and Armillaria mellea acidic polysaccharide (AMPA), were prepared and determined. AMPN and AMPA were separated and refined by the ion exchange column and gel chromatographycolumn. Analysis of AMPN and AMPA revealed molecular weights of 4.432 × 103 Da and 7.323 × 103 Da. The monosaccharide composition analysis revealed that AMPN was mainly composed of 68.3%glucose, while AMPA consisted primarily of glucose, mannose, and galactose, accompanied by 8.9% galacturonic acid and 3% fucose. Then, infrared spectra analysis, Congo red staining, methylation, and NMR spectroscopy analysis were conducted as a means to clarify the structure of AMPN and AMPA. The NMR spectra demonstrated that the two polysaccharides included both α and β-configuration glycosidic bonds. The Congo red experiment suggests that AMPN and AMPA all had obvious triple helix structures.The effects of AMPN and AMPA on immune repair ability were compared by immune deficiency mice. The activity experiment showed that AMPN and acidic polysaccharides extracted from the Armillaria fruiting body have biological immune activity. Among them, AMPA showed higher immune activity. These findings suggest that Armillaria mellea fruiting bodies may be used as a source of dietary supplements and functional products.
]]>Separations doi: 10.3390/separations11010002
Authors: Meijuan Zhao Fengyan Kuang Yingyue Zhang Guangping Lv
Monosaccharide composition analysis is essential to the structural characterization and research into the biological activity of polysaccharides. In this study, a systematic comparison was performed among commonly used monosaccharide composition analysis methods, including colorimetric and chromatographic methods. These were tested on 16 aldoses, ketoses, alditols, amino sugars, and uronic acids. Furthermore, the effect of hydrolysis methods was also investigated. The results showed that the phenol sulfuric acid method is greatly affected by the type of monosaccharide that is used as the reference substance. The determination of uronic acid using sulfuric acid carbazole is less affected by neutral sugars than that method using m-hydroxybiphenyl. The high-performance thin-layer chromatography (HPTLC) method can simultaneously analyze multiple samples and accurately determine the type of uronic acid. High-performance liquid chromatography (HPLC) can provide a good qualitative and quantitative analysis of aldose, amino sugars, and uronic acids, while gas chromatography–mass spectrometry (GC-MS) can detect aldose, ketose, and alditols. Fructose was detected in a large amount in inulin and Codonopsis pilosula after one-step hydrolysis, while it was totally destroyed in two-step hydrolysis. The release of galacturonic acid significantly increased after two-step hydrolysis in pectin and Lycium barbarum, which indicated that one-step hydrolysis is not enough for acidic polysaccharides. The results of this study are beneficial for selecting appropriate hydrolysis and analysis methods in order to accurately analyze the monosaccharide compositions of natural polysaccharides.
]]>Separations doi: 10.3390/separations11010001
Authors: Francisco Jose Alguacil
Since CO2 is an important component of gas emissions, its removal from gas streams is of the utmost importance to fulfill various environmental requirements. The technologies used to accomplish this removal are based mainly on absorption, as well as adsorption and membrane processing. Among the materials used in the above separation processes, materials in nano forms offer a potential alternative to other commonly used macromaterials. The present work reviews the most recent publications (2023) about CO2 capture using different nanomaterials, and whilst most of these publications were dedicated to investigating the above, several presented data on the separation of CO2 from other gases, namely nitrogen and methane. Furthermore, a number of publications investigated the recyclability of nanomaterials under continuous use, and just three of the references were about computational modeling; all others were experimental papers, and only one reference used a real industrial gas.
]]>Separations doi: 10.3390/separations10120602
Authors: Rana Salem Al Khulaifi Mohammed Mousa AlShehri Inas Al-Qadsy Mona A. Al Jufareen Waseem Sharaf Saeed Ahmed Yacine Badjah-Hadj-Ahmed Taieb Aouak
A comparative study of a Schiff base reaction involving benzaldehyde and n-butylamine was carried out to improve the yield of the resulting imine. This reaction was carried out at different temperatures without and with the elimination of the water produced during the process by the pervaporation (PV) technique using a typical cylindrical cell. To reach this goal, different dense membranes made of crosslinked poly(vinyl alcohol) with different oxalic acid (crosslinker) contents were prepared by the solvent casting method. Different parameters influencing the performance of the membrane in the separation process including swellability, diffusivity, crosslinking density, and thermal properties were investigated. The total and partial cumulative transmembranar fluxes as well as the separation factor were studied and the separation process was monitored by HPLC analysis. The n-butyl-1-phenylmethanimine produced was characterized by FTIR and 1HNMR analyses. The results obtained were a clear improvement in the yield of the reaction. For example, the yield obtained from the Schiff base reaction occurring without assistance by PV varied from 58 to 84 wt% when the temperature changed from 5 to 45 °C. On the other hand, when the PV process was used to eliminate water from this reaction mixture, the yield went from 90.4 to 98.6% by weight in this same temperature order. The cumulative total and partial fluxes significantly decreased with time. On the other hand, the separation factor reached a maximum at about one hour at 5, 15, and 45 °C. At 25 °C, the maximum total flux was reached at about 2 h of the PV process. The best selectivity of the PVA-0.5 membrane with regard to water was obtained at 15 °C. It was also revealed from the results obtained that the cumulative total and partial flux decreased rapidly with time and the separation factor reached a maximum at one hour into the PV process, in which 1.51 × 104 was reached at 15 °C, 6.25 × 103 and 3.50 × 103 at one hour of the separation process, and 10.23 × 103 at 25 °C at 2 h of the water removal by PV.
]]>Separations doi: 10.3390/separations10120601
Authors: Jin Sung Ahn Wan Kyunn Whang
Drynariae Rhizoma (DR) is a functional food and traditional medicine that has been widely used for bone and joint disorders for thousands of years. In this study, 14 compounds were isolated from DR, and their structures were identified using UPLC/QTOF–MS, UPLC–ESI/LTQ–Orbitrap–HRMS, and 2D NMR and compared with those obtained in previous studies. An HPLC–PDA multi-component simultaneous quantitative determination method was developed for 12 of the 14 DR-derived compounds, excluding compounds with a content <1.5 mg. The developed HPLC method was validated based on linearity (r2 ≥ 0.999), limit of detection (0.01–0.65 μg/mL), limit of quantification (0.04–1.97 μg/mL), intra-day precision and accuracy ranges (0.06–2.85% and 95.03–104.75%, respectively), and inter-day precision and accuracy ranges (0.24–2.83% and 95.75–105.75%, respectively). The developed analysis method improved the resolution of compounds 4 and 5. In addition, this is the first quantitative analysis of compounds 7, 8, and 11 and the first simultaneous quantitative analysis of 12 compounds, including compounds 4, 7, 8, 10, 11, and 14. This study developed a rapid, accurate, and economical HPLC method for performing the simultaneous quantitative analysis of 12 secondary metabolites isolated from DR.
]]>Separations doi: 10.3390/separations10120600
Authors: Risto Koivula Wenzhong Zhang
Metal(IV) phosphate and phosphonates materials have increasingly found their applications in water purification, heterogeneous catalysis, drug delivery, and proton-exchange membrane fuel cells. The strong linkage between tetravalent metal cations and phosphate/phosphonate groups offers a unique bottom-up design platform, resulting in chemically stable inorganics or hybrids. Task-specific physiochemical functionalities could be deposited by modifying the phosphate/phosphonate groups before the material synthesis. The high reactivity between the metal centre and the phosphorus-containing linker, on the other hand, often leads to obtaining unordered materials (amorphous solids or coordination polymers). The chemical composition of the prepared materials is a key parameter in guiding the synthetic approach and in governing their performances. This narrative review focuses on critically summarising the traditional and advanced analytical methods for probing the composition of these materials. The reader is introduced to and guided on the advances and restrictions of different analysis techniques when probing metal(IV) phosphates/phosphonates. Both solution-based and solid-state spectroscopic techniques are covered with a focus on understanding the quantity and the linkage status of the phosphorus-containing moieties. These techniques include atomic spectroscopy, mass spectroscopy, nuclear magnetic resonance spectroscopy, X-ray-based methods, and neutron activation analysis.
]]>Separations doi: 10.3390/separations10120599
Authors: Fatma Zohra Gharbi Nabil Bougdah Youghourta Belhocine Najoua Sbei Seyfeddine Rahali Maamar Damous Mahamadou Seydou
Due to their detrimental and carcinogenic effects, synthetic organic dyes pose significant environmental and health risks. Consequently, addressing the bioremediation of industrial wastewater containing these organic dyes has become an urgent environmental concern. The adsorption using low-cost and green materials is one of the best alternative techniques for the removal of dyes. This study aims to investigate the use of chitin to eliminate Congo red (CR), an anionic dye, from wastewater. The chitin was produced from shrimp shell in a quick and environmentally friendly manner by utilizing a co-solvent (glycerol/citric acid (GLC)). The resulting adsorbent was characterized through various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and FT-IR spectroscopy. The effectiveness of CR removal with chitin was studied with respect to contact time, adsorbent dose, initial pH, equilibrium isotherms, and kinetic and thermodynamic parameters. It was observed that variations in the dye concentration and pH significantly influenced the removal of CR with chitin. Under optimal operating conditions (pH = 7, contact time = 130 min, temperature = 50 °C), the adsorption capacity reached 29.69 ± 0.2 mg/g. The experimental data revealed that CR adsorption onto a chitin adsorbent is better represented by a Langmuir isotherm.
]]>Separations doi: 10.3390/separations10120598
Authors: Mengjie Zhang Jinhua Zhao Xiaofeng Dai Xiumei Li
There are many types of natural plants in nature that contain a variety of effective and complex chemical components. These constituents can be categorized as organic acids, volatile oils, coumarins, steroids, glycosides, alkaloids, carbohydrates, phytochromes, etc., all of which play important roles in the fields of pharmaceuticals, food, nutraceuticals, and cosmetics. The study of extraction and chemical composition analysis of natural products is important for the discovery of these active ingredients and their precursors. Therefore, the aim of this article is to review the status of research on the extraction, separation and purification, and structural identification of natural products, to provide a reference for the study of natural products.
]]>Separations doi: 10.3390/separations10120597
Authors: Zicheng Luo Shugen Hu Yameng Zhang Guanlong Yu Yunhe Yang Qing Li Peng Duan
Nitrogen pollution in water bodies presents a serious threat to ecosystems due to its role in eutrophication. In this study, the aerobic denitrifying bacterium Alcaligenes faecalis was used as a model microorganism to investigate the optimal operating conditions for nitrogen removal from nitrogen-containing wastewater by Alcaligenes faecalis under different aeration modes, microbial dosages and C/N ratios. The results showed that the optimal aeration mode for efficient bacterial denitrification was 10 min of aeration with a 30 min interval, and the total nitrogen removal reached 87.82%. At different bacterial doses, NO3−–N was completely denitrified and NO2−–N accumulation levels were reduced, all of which resulted in significant denitrification, and the final total nitrogen removal efficiencies reached 86.39–98.50%. With an increase in the C/N ratio, the pollutant removal performance of denitrifying bacteria increased. When the C/N ratio was 17, the final rates of NO3−–N, TN and COD removal were 100%, 98.50% and 96.13%, respectively. At lower C/N ratios, the growth and metabolism of microorganisms were inhibited and fewer electron acceptors were available during the denitrification process, which seriously affected denitrification performance. In this study, the denitrification performance of aerobic denitrifying bacterium Alcaligenes faecalis was explored in experiments using changes in aeration mode, microbial dosage and C/N ratio, and the optimal operating conditions of Alcaligenes faecalis for treating nitrogenous wastewater were indicated. This provides technical support for Alcaligenes faecalis in improving the remediation effect of nitrogenous wastewater and provides a theoretical basis for further in-depth research on the performance of Alcaligenes faecalis in the future.
]]>Separations doi: 10.3390/separations10120596
Authors: Weiwei Zhou Jun Li Xuefeng Wang Ling Liu Yun Li Rui Song Mengxue Zhang Xiumei Li
Essential oils (EOs), also called liquid gold, are known for their wide range of applications and biological activities. The modern use of EOs has received increasing attention for more than 60 years. The precious EOs have been refined from plant raw materials using a variety of methods. Since the extraction, separation, and purification methods determine the type, quantity, and stereochemical structure of EO molecules as well as the final yield and quality of EOs, the selection of an appropriate method is crucial. The traditional and emerging extraction methods (hydrodistillation, steam distillation, organic solvent extraction, etc.), as well as separation and purification methods (chromatography, macroporous resin, chemical reaction, etc.), of plant EOs and their main volatile compounds were shown. Our review focused on the principles, processes, characteristics, and applications of these methods, so as to better understand the preparation of pure plant EOs and further guide their large-scale use.
]]>Separations doi: 10.3390/separations10120595
Authors: Chengqi Tu Yongsheng Chang Xiaoshuang Dong Wei Huang
Cyanobacterial blooms in freshwater bodies are mainly attributed to the excess loading of nutrients. The microbes in sediments may affect nutrient migration and transformation during the growth of cyanobacteria. This study focused on the role of Paraburkholderia disturbance in affecting the sediment nutrient conditions and further contributing to cyanobacterial community succession in Meiliang Bay, Lake Taihu. The dissolving phosphorus and fixing nitrogen of Paraburkholderia with different concentration and characteristic capabilities, as well as the impact on nutrients (nitrogen (N), phosphorus (P), iron (Fe), etc.) in eutrophic lakes were determined. The results indicated that the various forms of phosphorus in the sediments showed total phosphorus (TP) > inorganic phosphorus (IP) > iron/aluminum-bound phosphate (NaOH-P) > algal-available phosphorus (AAP) > organic phosphorus (OP) > calcium-bound phosphate (HCl-P). Additionally, it was observed that with higher values of Paraburkholderia (OD600), the higher the corresponding risk of endogenous nutrient release from the sediments into the overlying water (but more is not always better), especially for the solubilization of HCl-P. The diffusion fluxes of TP, total nitrogen (TN) and Fe at the sediment–water interface (SWI) were all positive in the bacteria only experiment, with maximum values of 0.64, 15.0 and 5.02 mg/(m2d), respectively. Additionally, it was interesting that Paraburkholderia were able to produce organic acids, causing a decrease in pH. Furthermore, glucose levels can seriously affect water quality, especially the reduction in dissolved oxygen (DO) (down to 0.01 mg/L), leading to a series of side effects that have a huge impact on cyanobacterial community succession. These results provide a theoretical basis for the microbial ecological factors in eutrophic lakes.
]]>Separations doi: 10.3390/separations10120594
Authors: William C. Byrdwell Hari Kiran Kotapati
We analyzed ten pulses (the dried seeds of legumes), i.e., baby lima beans, black beans, black-eyed peas, butter beans, cranberry beans, garbanzo beans, green split peas, lentils, navy beans, and pinto beans, using three-dimensional liquid chromatography (3D-LC) with parallel second dimensions, LC × (LC + LC). We combined non-aqueous reversed-phase (NARP) chromatography as the first dimension separation, 1D, with argentation UHPLC for separation based on degree and location of unsaturation in the first second dimension, 2D(1), and multi-cycle NARP-UHPLC in the second second dimension, 2D(2). Pulses contained 1.9% to 2.7% lipids, except garbanzo beans, which contained 6.2% lipids. High-resolution, accurate-mass (HRAM) orbitrap mass spectrometry (MS) was used to perform lipidomic analysis of the 2D(2) and percent relative quantification, showing that the most abundant average triacylglycerol (TAG) molecular species across all pulses were PLL at 10.67% and PLLn at 10.45%. Common beans (Phaseolus vulgaris) were clustered together using principal component analysis (PCA), showing the highest levels of linolenic acid, C18:3, in molecular species such as PLnLn, LLnLn, and OLLn, with palmitic (P), C16:0, linoleic (L), 18:2, linolenic (Ln), 18:3, and oleic (O), 18:1, FAs. Calibration curves derived from interweaved sets of regioisomer standards allowed the absolute quantification of 1,2- and 1,3-regioisomers for a subset of TAGs.
]]>Separations doi: 10.3390/separations10120593
Authors: Guanlong Yu Jiajun Huang Huifang Chen Jundan Chen Shiyong Ge Jiaxin Liu Dian Zhen
Constructed wetlands (CWs) are a kind of green environmental protection technology, which are widely used in sewage treatment. Traditional CWs are faced with the problem of a low treatment effect of high-concentration sewage. In recent years, biochar, as a new type of adsorption material, has been used in CWs because of its advantages of large specific surface area, strong adsorption capacity, and wide material sources. This paper systematically summarized the characteristics of biochar and the preparation of biochar by studying the changes in microorganisms added to CWs and compared the effects of different treatment methods coupled with biochar on the treatment performance of CWs. The effects of biochar coupled with CWs on enzyme activity, functional genes, metabolites, and microbial communities were investigated. This review summarizes how different preparation methods affect the properties of biochar and how these biochar properties cause changes in the microorganisms added to CWs. It provides a new theoretical basis for the treatment of pollutants in CWs.
]]>Separations doi: 10.3390/separations10120592
Authors: Leonie Beek Wilhelm Barthlott Matthias Mail Kai Klopp Thomas Gries
Oil films on water are an increasingly major contamination problem worldwide. In 2020, we published a novel adsorption and transportation technology for oil–water separation based on biological role models like the floating fern Salvinia. This application provides an unexpected ability for the fast and efficient removal of oil films, particularly in ecologically important freshwater biota. A single small Bionic Oil Adsorber (BOA) with 1 m2 functional textile can collect up to 4 L of oil per hour, which equals about 100 m2 of oil film from a water surface into a collecting vessel. This is a safe, fast, and sustainable solution for the ubiquitous contaminations of, e.g., fuel oil in freshwater environments. Here, we present updated, new experimental data, and a review of the literature published since.
]]>Separations doi: 10.3390/separations10120591
Authors: Xiangwei Meng Ming Jin Qianzi Feng Aiqi Sha Shunwen Bai Xinyue Zhao
Livestock and poultry farming, as a crucial component of agricultural production, poses a substantial threat to the ecological environment due to the discharge of wastewater. In recent years, researchers have proposed various resource treatment technologies for livestock and poultry breeding wastewater. However, a comprehensive discussion regarding the limitations and avenues for optimizing resource utilization technologies for livestock and poultry farming wastewater treatment is notably absent in existing literature. This paper takes swine wastewater as an illustrative case and undertakes a review of the advantages, disadvantages, and optimization directions of resource treatment technologies, including physical and chemical technology, microbial metabolism, microbial electrochemistry, constructed wetlands, and microalgae-based techniques. Based on mass balance, the recovery rates of various treatment technologies are estimated, and it was found that microbial electrochemistry and constructed wetland techniques may become the mainstream for resource utilization in the future. Furthermore, this paper emphasizes that in addition to resource efficiency, the optimization of resource utilization technologies for swine wastewater should also focus on the following aspects: (1) striking a balance between environmental impact and economic benefits; (2) reducing the cost of resource and energy utilization; and (3) safeguarding environmental and ecological security.
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