Separations

14 pages, 1871 KiB

Open AccessArticle

Cost-Effective Simultaneous Determination of τ- and π-Methylhistidine in Dairy Bovine Plasma from Large Cohort Studies Using Hydrophilic Interaction Ultra-High Performance Liquid Chromatography Coupled to Tandem Mass Spectrometry

by Ioannis Sampsonidis, Maria Marinaki, Anastasia Pesiridou, Helen Gika, Georgios Theodoridis, Nektarios Siachos, Georgios Arsenos and Stavros Kalogiannis

Separations 2023, 10(2), 144; https://doi.org/10.3390/separations10020144 - 20 Feb 2023

Cited by 1 | Viewed by 2158

Abstract

The isomeric metabolites τ- and π-methylhistidine (formerly referred to as 3- and 1-methylhistidine) are known biomarkers for muscle protein breakdown and meat protein intake, frequently used in studies involving humans and animals. In the present study, we report the development and validation of [...] Read more.

The isomeric metabolites τ- and π-methylhistidine (formerly referred to as 3- and 1-methylhistidine) are known biomarkers for muscle protein breakdown and meat protein intake, frequently used in studies involving humans and animals. In the present study, we report the development and validation of a simple HILIC-MS/MS method for individual determination of τ-MH and π-MH in a large cohort of blood plasma samples from dairy cows. Their separate determination was achieved mainly through a mass spectrometry fragment ion study, which revealed that the two isomers exhibited distinct mass spectrometric behaviors at different collision energies. Chromatographic conditions were optimised to achieve better separation, minimizing inter-channel interference to less than 1% in both directions. A simple and effective sample clean-up method facilitated low laboratory manual workload. The analytical method was validated for the determination of τ-MH and π-MH in bovine plasma within a concentration range of 80 to 1600 μg/L and provided good linearity (>0.99 for both curves) and precision (<10%). Overall, the developed method enabled the determination of the two isomers in an efficient and economic-friendly manner suitable for large cohort bovine studies (involving hundreds to thousands of samples) mainly to provide data for statistical use. Full article

(This article belongs to the Special Issue Feature Papers in Separations from Editorial Board Members)

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27 pages, 1161 KiB

Open AccessEditor’s ChoiceReview

Renewable Resource Biosorbents for Pollutant Removal from Aqueous Effluents in Column Mode

by Lavinia Tofan and Daniela Suteu

Separations 2023, 10(2), 143; https://doi.org/10.3390/separations10020143 - 19 Feb 2023

Cited by 9 | Viewed by 3457

Abstract

The present work deals with the continuous flow systems based on renewable resource biosorbents towards the green removal of various categories of chemical pollutants from aqueous media. The opening discussions are focused on: (a) renewable resources; (b) biosorbents based on renewable resources; (c) [...] Read more.

The present work deals with the continuous flow systems based on renewable resource biosorbents towards the green removal of various categories of chemical pollutants from aqueous media. The opening discussions are focused on: (a) renewable resources; (b) biosorbents based on renewable resources; (c) dynamic biosorption. After these, the renewable resources biosorbents are reviewed according to the parameters of breakthrough curves. Subsequently, the targeted biosorbents are systematized and analyzed according to the following criteria: (a) their ability to work as remediation agents for heavy metal ions and dyes, respectively; (b) their relevancy for continuous biosorption processes applied both to synthetic aqueous solutions and real wastewaters. The perspective directions of research for the implementation of biosorbents from renewable resources in practical column strategies for wastewater treatment are recommended. Full article

(This article belongs to the Special Issue Removal of Emerging Pollutants and Environmental Analysis)

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23 pages, 1087 KiB

Open AccessReview

Contaminant Cocktails of High Concern in Honey: Challenges, QuEChERS Extraction and Levels

by Mariana Lamas, Francisca Rodrigues, Maria Helena Amaral, Cristina Delerue-Matos and Virgínia Cruz Fernandes

Separations 2023, 10(2), 142; https://doi.org/10.3390/separations10020142 - 18 Feb 2023

Cited by 5 | Viewed by 2595

Abstract

Environmental pollution is a crucial problem in our society, having nowadays a better understanding of its consequences, which include the increase of contaminant cocktails present in the environment. The contamination of honeybees can occur through their interaction with the nearby environment. Therefore, if [...] Read more.

Environmental pollution is a crucial problem in our society, having nowadays a better understanding of its consequences, which include the increase of contaminant cocktails present in the environment. The contamination of honeybees can occur through their interaction with the nearby environment. Therefore, if honeybees are previously contaminated, there is a possibility of contamination of their products, such as honey as natural, or minimally processed, product, resulting from the honeybees’ activity. Considering that honey is a highly consumed product, it is extremely necessary to control its quality and safety, including evaluating the presence and quantification of contaminants, which should follow monitoring studies and the legislation established by the European Union. This work aims to review the literature of different contaminants reported on honey, including pesticides, persistent organic pollutants, polycyclic aromatic hydrocarbons, and pharmaceuticals, focusing on the reports using the QuEChERS technique for the extraction. Furthermore, reports of microplastics on honey samples were also discussed. Despite the existence of several methods that identify and quantify these contaminants, few methods have been reported to operate with different groups of contaminants simultaneously. The development of methods with this characteristic (while being fast, low cost, and with a lower impact on the environment), monitoring studies to identify the risks, and an update on legislation are priority actions and future perspectives to follow. Full article

(This article belongs to the Section Analysis of Food and Beverages)

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13 pages, 1504 KiB

Open AccessArticle

Chemical Profiling of Significant Antioxidant and Phytotoxic Microwave-Extracted Essential Oil from Araucaria heterophylla Resin

by Ahmed M. Abd-ElGawad, Ibrahim Saleh, Mohamed H. Abd El-Razek, Asmaa S. Abd Elkarim, Yasser A. El-Amier, Tarik A. Mohamed, Abd El-Nasser G. El Gendy, Sherif M. Afifi, Tuba Esatbeyoglu and Abdelsamed I. Elshamy

Separations 2023, 10(2), 141; https://doi.org/10.3390/separations10020141 - 18 Feb 2023

Cited by 4 | Viewed by 2542

Abstract

Due to the various hazards of using synthetic chemical compounds in pharmaceutics, agriculture, and industry, scientists and researchers do their best to explore and assess new green natural compounds from natural resources with potent activity. The essential oil (EO) from the resin collected [...] Read more.

Due to the various hazards of using synthetic chemical compounds in pharmaceutics, agriculture, and industry, scientists and researchers do their best to explore and assess new green natural compounds from natural resources with potent activity. The essential oil (EO) from the resin collected from Araucaria heterophylla Salisb. was extracted by the microwave technique and chemically characterized via GC-MS analysis. Furthermore, the extract EO was assessed for its antioxidant and phytotoxic activities. The EO has 33 compounds, mainly terpenes (98.23%), and the major compounds were α-pinene (62.57%), β-pinene (6.60%), germacrene D (5.88%), and β-caryophyllene (3.56%). The extracted EO showed substantial antioxidant activity, where it showed IC₅₀ values of 142.42 and 118.03 mg L⁻¹ for DPPH and ABTS, respectively. On the other hand, the EO revealed considerable phytotoxicity against the weed Chenopodium murale, where the EO showed IC₅₀ values of 304.0, 230.1, and 147.1 mg L⁻¹, for seed germination, seedling shoot growth, and seedling root growth, respectively. Moreover, the EO showed the same pattern of allelopathic inhibition against the weed Sonchus oleraceus, where it showed IC₅₀ values of 295.7, 224.5, and 106.1 mg L⁻¹, for seed germination, seedling shoot growth, and seedling root growth, respectively. The present study showed that the extraction technique affects the constituents of the EO, particularly the quantitative composition. The EO of A. heterophylla resin also revealed considerable antioxidant and phytotoxic activity against weeds. Therefore, it can be considered a promising natural resource that could be integrated into the weed management approach. However, further study is recommended for deep characterization of their authentic compounds and evaluation of their mode of action(s) on a wide spectrum of weeds. Full article

(This article belongs to the Section Analysis of Natural Products and Pharmaceuticals)

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11 pages, 2070 KiB

Open AccessArticle

Development of a New Method to Estimate the Water Purification Efficiency of Bulk-Supported Nanosorbents under Realistic Conditions

by Elias Moisiadis, Anastasia D. Pournara, Manolis J. Manos and Dimosthenis L. Giokas

Separations 2023, 10(2), 140; https://doi.org/10.3390/separations10020140 - 18 Feb 2023

Cited by 1 | Viewed by 1636

Abstract

The direct use of nanosorbents for water purification is limited due to their aggregation and the lack of techniques for their recovery from natural waters. To overcome these problems, the affixation of nanomaterials onto bulk, non-mobile supports has been proposed. However, a method [...] Read more.

The direct use of nanosorbents for water purification is limited due to their aggregation and the lack of techniques for their recovery from natural waters. To overcome these problems, the affixation of nanomaterials onto bulk, non-mobile supports has been proposed. However, a method to simulate the efficiency of these sorbents under realistic conditions is still not available. To address this need, this work describes a method for evaluating the sorption efficiency of nanosorbent materials incorporated on bulk supports under non-equilibrium conditions. The method combines the principles of passive sampling, an environmental monitoring technique that is based on passive diffusion of dissolved contaminants from water to a sorbent, with batch sorption experiments that measure sorption under equilibrium conditions, to determine the parameters associated with water purification. These parameters are the maximum sorption capacity of the sorbent and the sampling rate, which is the volume of contaminated water treated per unit of time. From these variables, the deployment time of the sorbent until reaching saturation is proposed as an alternative indicator of sorbent efficiency. As proof-of-principle, the removal of oxyanions from a Zr-metal-organic framework (MOR−1) immobilized on cotton textiles was investigated. The results show that the sorption capacity under passive diffusion uptake conditions, is approximately 20 mg/g for As(VI) and 36 mg/g Se(IV), which is 10 to 30 times lower compared to that determined in batch sorption studies, indicating that conventional equilibrium sorption overestimates the efficiency of the sorbents under realistic conditions. The application of the method to a worst-case scenario, involving the severe contamination of freshwaters with arsenate species, is also demonstrated. Full article

(This article belongs to the Collection Feature Paper Collection in Section 'Materials in Separation Science')

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16 pages, 1094 KiB

Open AccessEditor’s ChoiceReview

Condensed Phase Membrane Introduction Mass Spectrometry: A Direct Alternative to Fully Exploit the Mass Spectrometry Potential in Environmental Sample Analysis

by Veronica Termopoli, Maurizio Piergiovanni, Davide Ballabio, Viviana Consonni, Emmanuel Cruz Muñoz and Fabio Gosetti

Separations 2023, 10(2), 139; https://doi.org/10.3390/separations10020139 - 17 Feb 2023

Cited by 4 | Viewed by 2723

Abstract

Membrane introduction mass spectrometry (MIMS) is a direct mass spectrometry technique used to monitor online chemical systems or quickly quantify trace levels of different groups of compounds in complex matrices without extensive sample preparation steps and chromatographic separation. MIMS utilizes a thin, semi-permeable, [...] Read more.

Membrane introduction mass spectrometry (MIMS) is a direct mass spectrometry technique used to monitor online chemical systems or quickly quantify trace levels of different groups of compounds in complex matrices without extensive sample preparation steps and chromatographic separation. MIMS utilizes a thin, semi-permeable, and selective membrane that directly connects the sample and the mass spectrometer. The analytes in the sample are pre-concentrated by the membrane depending on their physicochemical properties and directly transferred, using different acceptor phases (gas, liquid or vacuum) to the mass spectrometer. Condensed phase (CP) MIMS use a liquid as a medium, extending the range to new applications to less-volatile compounds that are challenging or unsuitable to gas-phase MIMS. It directly allows the rapid quantification of selected compounds in complex matrices, the online monitoring of chemical reactions (in real-time), as well as in situ measurements. CP-MIMS has expanded beyond the measurement of several organic compounds because of the use of different types of liquid acceptor phases, geometries, dimensions, and mass spectrometers. This review surveys advancements of CP-MIMS and its applications to several molecules and matrices over the past 15 years. Full article

(This article belongs to the Section Environmental Separations)

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14 pages, 2012 KiB

Open AccessArticle

A Validated, Stability-Indicating, Eco-Friendly HPTLC Method for the Determination of Cinnarizine

by Mohammed H. Alqarni, Faiyaz Shakeel, Ahmed I. Foudah, Tariq M. Aljarba, Wael A. Mahdi, Fatma M. Abdel Bar, Sultan Alshehri and Prawez Alam

Separations 2023, 10(2), 138; https://doi.org/10.3390/separations10020138 - 17 Feb 2023

Cited by 6 | Viewed by 2063

Abstract

The eco-friendly high-performance thin-layer chromatographic (HPTLC) approaches for measuring cinnarizine (CIN) are scant in reported databases. As a result, the current work has developed and validated an eco-friendly HPTLC technique for assessing CIN in commercial formulations. The proposed approach was based the use [...] Read more.

The eco-friendly high-performance thin-layer chromatographic (HPTLC) approaches for measuring cinnarizine (CIN) are scant in reported databases. As a result, the current work has developed and validated an eco-friendly HPTLC technique for assessing CIN in commercial formulations. The proposed approach was based the use of ethyl alcohol-water (90:10 v/v) as the eco-friendly mobile phase. A wavelength of 197 nm was used to detect CIN. The greenness score of the current approach was measured using the Analytical GREENness (AGREE) approach. The current approach was linear for CIN measurement in 50–800 ng band⁻¹ range. The current approach for CIN measurement was validated successfully using ICH guidelines and was found to be linear, accurate (% recovery = 99.07–101.29%), precise (% CV = 0.80–0.95%), robust, sensitive (LOD = 16.81 ng band⁻¹ and LOQ = 50.43 ng band⁻¹), specific, selective, stability-indicating, and eco-friendly. The AGREE score for the current approach was calculated to be 0.80, showing an excellent greenness characteristic of the present approach. Under forced degradation conditions, the current approach was successful in separating the CIN degradation product, demonstrating the stability-indicating qualities/selectivity of the present approach. The % assay of CIN in commercial tablet brands A and B was found to be 98.64 and 101.22%, respectively, suggesting the reliability of the present approach in the pharmaceutical analysis of CIN in commercial dosage forms. The obtained findings indicated that CIN in commercial formulations could be routinely determined using the current approach. Full article

(This article belongs to the Section Analysis of Natural Products and Pharmaceuticals)

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15 pages, 5418 KiB

Open AccessArticle

Effect of Hydrothermal Conditions on Kenaf-Based Carbon Quantum Dots Properties and Photocatalytic Degradation

by Nabilah Saafie, Nonni Soraya Sambudi, Mohd Dzul Hakim Wirzal and Suriati Sufian

Separations 2023, 10(2), 137; https://doi.org/10.3390/separations10020137 - 17 Feb 2023

Cited by 5 | Viewed by 2217 | Correction

Abstract

The development of biomass-based CQD is highly attentive to enhancing photocatalytic performance, especially in secondary or ternary heterogeneous photocatalysts by allowing for smooth electron-hole separation and migration. In this study, kenaf-based carbon quantum dots (CQD) were prepared. The main objective of the current [...] Read more.

The development of biomass-based CQD is highly attentive to enhancing photocatalytic performance, especially in secondary or ternary heterogeneous photocatalysts by allowing for smooth electron-hole separation and migration. In this study, kenaf-based carbon quantum dots (CQD) were prepared. The main objective of the current work was to investigate temperature, precursor mass and time in hydrothermal synthesis treatment to improve the CQD properties and methylene blue photocatalytic degradation. Optimization of kenaf-based CQD for inclusion in hydrothermal treatment was analyzed. The as-prepared CQDs were characterized in detail by Fourier transform infrared (FTIR) spectroscopy, using a Hitachi TEM System (HT7830, RuliTEM, Tokyo, Japan), by photoluminescence (PL), and by ultraviolet-visible (UV-Vis) spectroscopy. It was found that C200-0.5-24 exhibits a higher photocatalytic activity of the methylene blue dye and optimized hydrothermal conditions of 200 °C, 0.5 g and 24 h. Therefore, novel kenaf-based CQD was synthesized for the first time and was successfully optimized in the as-mentioned conditions. During the hydrothermal treatment, precursor mass controls the size and the distribution of CQD nanoparticles formed. The C200-0.5-24 showed a clearly defined and well-distributed CQD with an optimized nanoparticle size of 8.1 ± 2.2 nm. Indeed, the C200-0.5-24 shows the removal rate of 90% of MB being removed within 120 min. Full article

(This article belongs to the Section Environmental Separations)

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13 pages, 2537 KiB

Open AccessArticle

Green Automated Solid Phase Extraction to Measure Levofloxacin in Human Serum via Liquid Chromatography with Fluorescence Detection for Pharmacokinetic Study

by Hager Ebrahim, Heba Sonbol, Monika Malak, Ahmed Ali, Yasmine Aboulella, Ghada Hadad, Walaa Zarad, Samy Emara and Lamyaa Bazan

Separations 2023, 10(2), 136; https://doi.org/10.3390/separations10020136 - 17 Feb 2023

Cited by 2 | Viewed by 2258

Abstract

A simple, selective, rapid, sensitive and less costly green automated solid phase extraction bio-analytical high-performance liquid chromatographic-based technique with fluorescence detection (Aut-SPE-BA-HPLC-FL) for the quantification of levofloxacin in human serum samples has been developed and validated. The serum samples were loaded into the [...] Read more.

A simple, selective, rapid, sensitive and less costly green automated solid phase extraction bio-analytical high-performance liquid chromatographic-based technique with fluorescence detection (Aut-SPE-BA-HPLC-FL) for the quantification of levofloxacin in human serum samples has been developed and validated. The serum samples were loaded into the chromatographic system without prior treatment and then injected into short (20 mm × 4.6 mm, 20 µm) protein-coated (PC) µBondapak CN (µBCN) silica pre-column (PC-µBCN-pre-column). Levofloxacin was retained and pre-concentrated on the head of the PC-µBCN-pre-column, while proteins and other polar components were eliminated using phosphate buffer saline (PBS), pH 7.4, as the first mobile phase in the extraction step. Levofloxacin is then transferred to the analytical column; ZORBAX Eclipse XDB-C18 (150 mm × 46 mm, 5 µm), through the aid of a column-switching valve technique, on-throughs the elution mode using the second mobile phase containing a methanol and phosphate buffer (0.05 M, pH 5) in a ratio of 70:30 (v/v). Levofloxacin signals were detected using a fluorescence detector operated at excitation/emission wavelengths of 295/500 nm. The proposed Aut-SPE-BA-HPLC-FL methodology showed linearity over a levofloxacin concentration range of 10–10,000 ng/mL (r² = 0.9992), with good recoveries ranging from 87.12 to 97.55%. Because of the validation qualities in terms of linearity, recovery, precision, accuracy, selectivity and robustness, the Aut-SPE-BA-HPLC-FL method has been used in some clinical trials for therapeutic drug monitoring and the pharmacokinetic study of levofloxacin in human serum. Full article

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16 pages, 2629 KiB

Open AccessArticle

Examination of Condensation Liquid Formation in Istanbul Natural Gas Distribution Network

by Eyüp Numan Aytaş and Ali Volkan Akkaya

Separations 2023, 10(2), 135; https://doi.org/10.3390/separations10020135 - 16 Feb 2023

Viewed by 1761

Abstract

In this study, the formation of natural gas liquid in gas distribution lines, particularly at regional stations, service boxes, customer installations, and gas meters, was investigated. The study aims to address the problems associated with natural gas liquid formation, such as interruption of [...] Read more.

In this study, the formation of natural gas liquid in gas distribution lines, particularly at regional stations, service boxes, customer installations, and gas meters, was investigated. The study aims to address the problems associated with natural gas liquid formation, such as interruption of supply and decreased efficiency of combustion devices. The indirect measurement of the hydrocarbon dew point was analyzed using C₆₊ chromatograph data, and the model based on directly measured C₆₊ data were converted into C₆/C₇/C₈ data by four different methods. As distinct from studies in the literature, this study experimentally determines the distribution of heavy hydrocarbons from C₉ to C₁₉ based on indirect methods for acquiring C₈₊ data and direct measurement of C₆₊ data. The hydrocarbon dew point temperature was calculated using the Peng–Robinson (PR) and Soave–Redlich–Kwong (SRK) equations of state. The results of the analysis performed on two city gate stations showed that the critical temperatures were 4.21 °C at a pressure of 10.81 bar and 8.27 °C at a pressure of 11.25 bar, respectively. These values were obtained from a model designed to determine the dew point temperature in the area where natural gas liquid formation was most prevalent. The experimental analysis and indirect measurements indicated the occurrence of a two-phase gas–liquid formation. Full article

(This article belongs to the Special Issue Comprehensive Separations of Complex Mixtures by Gas Chromatography/Mass Spectrometry)

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15 pages, 5454 KiB

Open AccessArticle

Multiscale Analysis of Permeable and Impermeable Wall Models for Seawater Reverse Osmosis Desalination

by Qingqing Yang, Yi Heng, Ying Jiang and Jiu Luo

Separations 2023, 10(2), 134; https://doi.org/10.3390/separations10020134 - 15 Feb 2023

Cited by 3 | Viewed by 1842

Abstract

In recent years, high permeability membranes (HPMs) have attracted wide attention in seawater reverse osmosis (SWRO) desalination. However, the limitation of hydrodynamics and mass transfer characteristics for conventional spiral wound modules defeats the advantage of HPMs. Feed spacer design is one of the [...] Read more.

In recent years, high permeability membranes (HPMs) have attracted wide attention in seawater reverse osmosis (SWRO) desalination. However, the limitation of hydrodynamics and mass transfer characteristics for conventional spiral wound modules defeats the advantage of HPMs. Feed spacer design is one of the effective ways to improve module performance by enhancing permeation flux and mitigating membrane fouling. Herein, we propose a multiscale modeling framework that integrates a three-dimensional multi-physics model with a permeable wall and an impermeable wall, respectively, at a sub-millimeter scale and a system-level model at a meter scale. Using the proposed solution framework, a thorough quantitative analysis at different scales is conducted and it indicates that the average errors of the friction coefficient and the Sherwood number using the impermeable wall model are less than 2% and 9%, respectively, for commercial SWRO membrane (water permeability 1 L m⁻² h⁻¹ bar⁻¹) and HPMs (3 L m⁻² h⁻¹ bar⁻¹, 5 L m⁻² h⁻¹ bar⁻¹ and 10 L m⁻² h⁻¹ bar⁻¹) systems, compared to the predictions using the permeable wall model. Using both the permeable and impermeable wall models, the system-level simulations, e.g., specific energy consumption, average permeation flux, and the maximum concentration polarization factor at the system inlet are basically the same (error < 2%), while the impermeable wall model has a significant advantage in computational efficiency. The multiscale framework coupling the impermeable wall model can be used to guide the efficient and accurate optimal spacer design and system design for HPMs using, e.g., a machine learning approach. Full article

(This article belongs to the Special Issue Modeling, Simulation, and Optimization of Membrane Processes)

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15 pages, 1714 KiB

Open AccessArticle

Surfactant-Enhanced Extraction of Lutein from Marigold Petals using an Aqueous Two-Phase System

by Neha Maheshwari, Raj Kumar Arya, George D. Verros, Pradip B. Dhamole and Ashwin Kannan

Separations 2023, 10(2), 133; https://doi.org/10.3390/separations10020133 - 15 Feb 2023

Cited by 7 | Viewed by 3931

Abstract

The extraction of lutein from marigold petals using a surfactant-based aqueous two-phase system is reported. In this work, the effectiveness of the hydrophilic-lipophilic balance of surfactants on extraction performance for the extraction of lutein from marigold petal powder was demonstrated using aqueous solutions [...] Read more.

The extraction of lutein from marigold petals using a surfactant-based aqueous two-phase system is reported. In this work, the effectiveness of the hydrophilic-lipophilic balance of surfactants on extraction performance for the extraction of lutein from marigold petal powder was demonstrated using aqueous solutions of a wide range of non-ionic surfactants. The response surface methodology was applied to obtain optimised conditions for maximum extraction of lutein. At the optimised conditions (Temperature = 37.5 °C, S/L = 0.00375, and surfactant amount = 1.5% (v/v)), 12.12 ± 0.16 mg/g of lutein was obtained. Furthermore, the surface morphology of marigold petal powder (MPP) was analysed using SEM micrographs. Significant changes in surface morphology were observed which suggested better access of surfactant solution to the targeted biomolecule implanted in the matrix. Finally, the antioxidant activity of the obtained lutein extract was analysed using 2,2-diphenyl-1-picrylhydrazyl (DPPH). Results suggest that the antioxidant activity of the lutein extract obtained by the surfactant-based system is more than that of the lutein extract obtained by organic solvents. The aforementioned results suggest that the lutein can be extracted using a surfactant-based aqueous two-phase system (ATPS). Full article

(This article belongs to the Special Issue Novel Applications of Separation Technology)

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26 pages, 1814 KiB

Open AccessEditor’s ChoiceReview

Potential of Advanced Oxidation as Pretreatment for Microplastics Biodegradation

by Kristina Bule Možar, Martina Miloloža, Viktorija Martinjak, Matija Cvetnić, Hrvoje Kušić, Tomislav Bolanča, Dajana Kučić Grgić and Šime Ukić

Separations 2023, 10(2), 132; https://doi.org/10.3390/separations10020132 - 15 Feb 2023

Cited by 17 | Viewed by 5469

Abstract

In the last two decades, microplastics (MP) have been identified as an emerging environmental pollutant. Due to their small size, MP particles may easily enter the food chain, where they can have adverse effects on organisms and the environment in general. The common [...] Read more.

In the last two decades, microplastics (MP) have been identified as an emerging environmental pollutant. Due to their small size, MP particles may easily enter the food chain, where they can have adverse effects on organisms and the environment in general. The common methods for the removal of pollutants from the environment are not fully effective in the elimination of MP; thus, it is necessary to find a more suitable treatment method(s). Among the various approaches tested, biodegradation is by far the most environmentally friendly and economically acceptable remediation approach. However, it has serious drawbacks, generally related to the rather low removal rate and often insufficient efficiency. Therefore, it would be beneficial to use some of the less economical but more efficient methods as pretreatment prior to biodegradation. Such pretreatment would primarily serve to increase the roughness and hydrophilicity of the surface of MP, making it more susceptible to bioassimilation. This review focuses on advanced oxidation processes (AOPs) as treatment methods that can enhance the biodegradation of MP particles. It considers MP particles of the six most commonly used plastic polymers, namely: polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyethylene terephthalate and polyurethane. The review highlights organisms with a high potential for biodegradation of selected MP particles and presents the potential benefits that AOP pretreatment can provide for MP biodegradation. Full article

(This article belongs to the Special Issue Separation and Analysis of Micro- and Nanoplastics in the Environment)

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13 pages, 4826 KiB

Open AccessArticle

Chemical Influence of Scutellaria baicalensis—Coptis chinensis Pair on the Extraction Efficiencies of Flavonoids and Alkaloids at Different Extraction Times and Temperatures

by Han-Young Kim and Jung-Hoon Kim

Separations 2023, 10(2), 131; https://doi.org/10.3390/separations10020131 - 15 Feb 2023

Cited by 4 | Viewed by 1677

Abstract

The Scutellaria baicalensis—Coptis chinensis pair is an herbal combination used for the treatment of various heat-related diseases. During the extraction process, two herbs can mutually influence the extraction efficiency of the chemical constituents contained in each herb. The concentrations of five [...] Read more.

The Scutellaria baicalensis—Coptis chinensis pair is an herbal combination used for the treatment of various heat-related diseases. During the extraction process, two herbs can mutually influence the extraction efficiency of the chemical constituents contained in each herb. The concentrations of five flavonoids from S. baicalensis and seven alkaloids from C. chinensis were compared in paired or single hot-water extracts at different temperatures (80, 90, and 100 °C) and extraction times (60, 90, and 120 min). Temperature- and time-dependent increases in marker compound concentrations were observed in both paired and single extracts, with the exception of baicalin, berberine, and coptisine in the paired extracts at 100 °C. However, the extractions of the compounds in the paired and single extracts were affected differently by the extraction conditions. Furthermore, the concentrations of most marker compounds in single extracts were 1.09–44.13 times those in paired extracts. The contents of baicalin, wogonoside, coptisine, and berberine, known to be easily aggregated by the flavonoid–alkaloid complex, were changed by 0.024–0.764-fold in the paired extract. The effect of extraction temperature and time on the formation of the flavonoid–alkaloid complex was not significant. The extraction efficiency of the flavonoids and alkaloids can be affected by the pair of S. baicalensis—C. chinensis, which is a primary factor in the chemical modification of two herb-containing herbal extracts. Full article

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14 pages, 2830 KiB

Open AccessArticle

Influence of Chemical Pretreatment on the Adsorption of N₂ and O₂ in Ca-Clinoptilolite

by Miguel Ángel Hernández, Gabriela I. Hernández, Roberto Ignacio Portillo, Ma de los Ángeles Velasco, Juana Deisy Santamaría-Juárez, Efraín Rubio and Vitalii Petranovskii

Separations 2023, 10(2), 130; https://doi.org/10.3390/separations10020130 - 15 Feb 2023

Cited by 2 | Viewed by 1798

Abstract

N₂ and O₂ adsorption isotherms in chemically modified clinoptilolite-Ca zeolites were experimentally estimated by inverse adsorption chromatography. Natural zeolites (CLINA) were chemically treated with HCl at different concentrations (H1-H4). The adsorption of N₂ and O₂ on these zeolites was [...] Read more.

N₂ and O₂ adsorption isotherms in chemically modified clinoptilolite-Ca zeolites were experimentally estimated by inverse adsorption chromatography. Natural zeolites (CLINA) were chemically treated with HCl at different concentrations (H1-H4). The adsorption of N₂ and O₂ on these zeolites was studied in the temperature zone of 398–498 K using gas chromatography. This technique used a thermal-conductivity detector and He as carrier gas, at a rate of 30 mL min⁻¹. The Langmuir and Henry equations were used to describe the experimental results of these gases’ adsorption. To evaluate the selectivity of the components of atmospheric air, the chemical activation of the zeolite clinoptilolite-Ca has been carried out. The results are attractive because of the ability to separate the gases these nanomaterials present under dynamic conditions. The structural modifications of the crystalline phases of the studied zeolites were carried out through X-ray diffraction, where the average crystal size was evaluated with the Scherrer equation, finding values of 25.86 nm for CLINA and 15.12 nm for H3 zeolites. The variation of their chemical composition was carried out by energy-dispersive EDS, while the adsorption of N₂ carried out their texture properties at 77 K. The selectivity coefficients (α) were evaluated for these gases in pure form and in a mixture (atmospheric air), finding the highest values in zeolites H4 and H3. The interaction energies between these gases with the porous structures of the studied zeolites were evaluated from the evolution of the isosteric enthalpies of adsorption through the Clausius–Clapeyron equation. Full article

(This article belongs to the Special Issue Research on Adsorption and Purification Technology of Water and Air Pollution)

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15 pages, 2762 KiB

Open AccessArticle

The Potential of Membrane Contactors in the Pre-Treatment and Post-Treatment Lines of a Reverse Osmosis Desalination Plant

by Alessandra Criscuoli

Separations 2023, 10(2), 129; https://doi.org/10.3390/separations10020129 - 14 Feb 2023

Viewed by 1648

Abstract

The flexibility of membrane contactors (MCs) is highlighted for a reverse osmosis (RO) desalination plant. MCs are applied as pre-treatment for the oxygen removal and the pH reduction of seawater, also as post-treatment for the pH increase of the RO permeate and the [...] Read more.

The flexibility of membrane contactors (MCs) is highlighted for a reverse osmosis (RO) desalination plant. MCs are applied as pre-treatment for the oxygen removal and the pH reduction of seawater, also as post-treatment for the pH increase of the RO permeate and the reduction of the RO brine volume. A decrease of the seawater pH down to neutral values, as needed when coagulation is used in the pre-treatment line of RO, together with an increase of the RO permeate pH up to 7.58, matching the target of produced water, can be obtained without the use of chemicals. Direct Contact Membrane Distillation (DCMD) and Vacuum Membrane Distillation (VMD) are investigated as function of the feed concentration (ranging from 40 g/L to 80 g/L) and temperature (40 °C–80° C). Their performance is compared at parity of operating conditions and in terms of applied driving force. Both distillation systems are able to efficiently reject salts (rejection > 99.99%), while higher distillate fluxes are obtained when a vacuum is applied at the permeate side (15 kg/m²h vs. 6.6 kg/m²h for the 80 g/L feed). Full article

(This article belongs to the Special Issue Feature Papers in Separations from Editorial Board Members)

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15 pages, 1700 KiB

Open AccessEditor’s ChoiceArticle

Effect of Extraction Methods on Essential Oil Composition: A Case Study of Irish Bog Myrtle-Myrica gale L.

by Shipra Nagar, Maria Pigott, Sophie Whyms, Apolline Berlemont and Helen Sheridan

Separations 2023, 10(2), 128; https://doi.org/10.3390/separations10020128 - 14 Feb 2023

Cited by 2 | Viewed by 3915

Abstract

Myrica gale is an aromatic peatland shrub that has reported traditional use as an insect repellent. Different extraction methodologies were used in this study to isolate the essential oil of Myrica gale L., including Clevenger hydrodistillation (CH) and microwave-assisted hydrodistillation (MAH). The oils, [...] Read more.

Myrica gale is an aromatic peatland shrub that has reported traditional use as an insect repellent. Different extraction methodologies were used in this study to isolate the essential oil of Myrica gale L., including Clevenger hydrodistillation (CH) and microwave-assisted hydrodistillation (MAH). The oils, isolated from different plant parts (leaves, fruit and branches) collected in summer and autumn, were analysed by GC-MS and the volatiles from plant tissue were directly analysed by headspace-GC-MS. A total of 58 components were identified, including 15 monoterpene hydrocarbons (22.78–98.98%), 14 oxygenated monoterpenes (0.91–43.02%), 13 sesquiterpene hydrocarbons (0.05–24.98%), 3 oxygenated sesquiterpenes (0.07–13.16%) and 13 other compounds (0.05–5.21%). Headspace sampling furnished monoterpenes, while CH and MAH extracted monoterpenes and sesquiterpenes, with α-pinene (6.04–70.45%), eucalyptol (0.61–33.80%), limonene (2.27–20.73%) and α-phellandrene (2.33–15.61%) as major components in all plant parts. Quantitative differences occurred between extraction methodologies, with MAH yielding higher quantities of monoterpene and sesquiterpene hydrocarbons and CH targeting oxygenated counterparts. Leaves gave more complex chemical fingerprints than branches and fruit, and the summer collection yielded more components than the autumn collections. An OPLS-DA model was applied to the GC-MS data to compare the chemical profiles based on the extraction techniques and plant parts, and molecular networks were obtained for monoterpenes and sesquiterpenes connected via biosynthetic pathways. The essential oil profile of Myrica gale was influenced by the season of collection, plant part and extraction method. Full article

(This article belongs to the Section Analysis of Natural Products and Pharmaceuticals)

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12 pages, 2376 KiB

Open AccessArticle

Application of Encapsulated Quorum Quenching Strain Acinetobacter pittii HITSZ001 to a Membrane Bioreactor for Biofouling Control

by Yongmei Wang, Xiaochi Feng, Wenqian Wang, Hongtao Shi, Zijie Xiao, Chenyi Jiang, Yujie Xu, Xin Zhang and Nanqi Ren

Separations 2023, 10(2), 127; https://doi.org/10.3390/separations10020127 - 13 Feb 2023

Cited by 3 | Viewed by 1586

Abstract

Quorum quenching (QQ) is a novel anti-biofouling strategy for membrane bioreactors (MBRs) used in wastewater treatment. However, actual operation of QQ-MBR systems for wastewater treatment needs to be systematically studied to evaluate the comprehensive effects of QQ on wastewater treatment engineering applications. In [...] Read more.

Quorum quenching (QQ) is a novel anti-biofouling strategy for membrane bioreactors (MBRs) used in wastewater treatment. However, actual operation of QQ-MBR systems for wastewater treatment needs to be systematically studied to evaluate the comprehensive effects of QQ on wastewater treatment engineering applications. In this study, a novel QQ strain, Acinetobacter pittii HITSZ001, was encapsulated and applied to a MBR system to evaluate the effects of this organism on real wastewater treatment. To verify the effectiveness of immobilized QQ beads in the MBR system, we examined the MBR effluent quality and sludge characteristics. We also measured the extracellular polymeric substances (EPS) and soluble microbial products (SMP) in the system to determine the effects of the organism on membrane biofouling inhibition. Additionally, changes in microbial communities in the system were analyzed by high-throughput sequencing. The results indicated that Acinetobacter pittii HITSZ001 is a promising strain for biofouling reduction in MBRs treating real wastewater, and that immobilization does not affect the biofouling control potential of QQ bacteria. Full article

(This article belongs to the Section Materials in Separation Science)

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22 pages, 1991 KiB

Open AccessReview

Research Progress on Extraction and Separation of Active Components from Loquat Leaves

by Siqiu Xiao, Wei Wang and Ying Liu

Separations 2023, 10(2), 126; https://doi.org/10.3390/separations10020126 - 13 Feb 2023

Cited by 3 | Viewed by 3688

Abstract

Loquat is an evergreen tree belonging to the genus Loquat in Rosaceae. It is widely used in the processing of food and medicine. Based on the literature findings, the anti-tumor, antibacterial, anti-inflammatory and anti-oxidation activities of the extracted loquat leaves are related to [...] Read more.

Loquat is an evergreen tree belonging to the genus Loquat in Rosaceae. It is widely used in the processing of food and medicine. Based on the literature findings, the anti-tumor, antibacterial, anti-inflammatory and anti-oxidation activities of the extracted loquat leaves are related to its active components. The extracted loquat leaves, in addition, demonstrated remarkable, and privileged medicinal and commercial values, and recently attracted the interest of researchers. The current review aimed to summarize several important bioactive components in loquat leaves, their extraction and separation techniques, pharmacological activities, and research progress. In addition, the application prospect of bioactive components from loquat leaves was prospected, which provided a theoretical basis for its further development and utilization. Full article

(This article belongs to the Section Analysis of Natural Products and Pharmaceuticals)

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32 pages, 3605 KiB

Open AccessReview

Advancements in Clay Materials for Trace Level Determination and Remediation of Phenols from Wastewater: A Review

by Zakariyya Uba Zango, Muhammad Nur’Hafiz Rozaini, Noor Hana Hanif Abu Bakar, Muttaqa Uba Zango, Maje Alhaji Haruna, John Ojur Dennis, Ahmed Alsadig, Khalid Hassan Ibnaouf, Osamah A. Aldaghri and Ismael Abdalla Wadi

Separations 2023, 10(2), 125; https://doi.org/10.3390/separations10020125 - 10 Feb 2023

Cited by 8 | Viewed by 1918

Abstract

The wide spread of phenols and their toxicity in the environment pose a severe threat to the existence and sustainability of living organisms. Rapid detection of these pollutants in wastewaters has attracted the attention of researchers from various fields of environmental science and [...] Read more.

The wide spread of phenols and their toxicity in the environment pose a severe threat to the existence and sustainability of living organisms. Rapid detection of these pollutants in wastewaters has attracted the attention of researchers from various fields of environmental science and engineering. Discoveries regarding materials and method developments are deemed necessary for the effective detection and remediation of wastewater. Although various advanced materials such as organic and inorganic materials have been developed, secondary pollution due to material leaching has become a major concern. Therefore, a natural-based material is preferable. Clay is one of the potential natural-based sorbents for the detection and remediation of phenols. It has a high porosity and polarity, good mechanical strength, moisture resistance, chemical and thermal stability, and cation exchange capacity, which will benefit the detection and adsorptive removal of phenols. Several attempts have been made to improve the capabilities of natural clay as sorbent. This manuscript will discuss the potential of clays as sorbents for the remediation of phenols. The activation, modification, and application of clays have been discussed. The achievements, challenges, and concluding remarks were provided. Full article

(This article belongs to the Special Issue Photocatalysis and Adsorption Techniques in Water and Wastewater Treatment)

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17 pages, 2377 KiB

Open AccessArticle

Synthesis and Surface Modification of Iron Oxide Nanoparticles for the Extraction of Cadmium Ions in Food and Water Samples: A Chemometric Study

by Faheem Shah and Munazza Ghafoor

Separations 2023, 10(2), 124; https://doi.org/10.3390/separations10020124 - 10 Feb 2023

Cited by 3 | Viewed by 1818

Abstract

In this project, a prompt, efficient, and effective method for Cd²⁺ ions extraction from different food and water samples using magnetic dispersion-based solid phase extraction by functionalized iron oxide nanoparticles was proposed. Iron oxide nanoparticles were synthesized through the co-precipitation method followed [...] Read more.

In this project, a prompt, efficient, and effective method for Cd²⁺ ions extraction from different food and water samples using magnetic dispersion-based solid phase extraction by functionalized iron oxide nanoparticles was proposed. Iron oxide nanoparticles were synthesized through the co-precipitation method followed by functionalization with tetraethyl orthosilicate (TEOS) and 3-aminopropyl silane (APTES) to obtain Fe₃O₄@SiO₂@APTES. This composite was characterized through different techniques, including vibrating sample magnetometer, dynamic light scattering, zeta potential, FTIR, SEM, XRD, and BET. Variables studied were pH, temperature, sorbent amount, sonication time, and sample and eluent volume affecting the sorption efficacy of freshly synthesized sorbent. Plackett–Burman design was utilized for the identification of significant factors for microextraction of target analyte, while the central composite design was utilized for the optimization of significant factors. Detection and quantification limits obtained were 0.17 and 0.58 μgL⁻¹, respectively, with an enhancement factor of 83.5. Under optimum conditions, Fe₃O₄@SiO₂@APTES showed good stability even after >80 adsorption/desorption cycles run while maintaining over 96% analyte recoveries. The developed method was validated by assessing certified reference materials and standard addition methodology for Cd²⁺ detection in real samples. To confirm the precision, repeatability (RSD_r) and reproducibility (RSD_R) were calculated and found as <3.0 (n = 7) and <7.5 (n = 15), respectively. Furthermore, in accordance with the ISO/IEC 17025 recommendations, the validation was also confirmed through a “bottom-up” approach while considering all possible uncertainties in data. Full article

(This article belongs to the Special Issue Advanced Methods for Extraction and Determination of Metals and Trace Elements in Food and Environmental Samples)

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17 pages, 2798 KiB

Open AccessArticle

Combined Effects of Polyamide Microplastics and Hydrochemical Factors on the Transport of Bisphenol A in Groundwater

by Zhou Cheng, Xuanhao Lin, Ming Wu, Guoping Lu, Yanru Hao, Cehui Mo, Qusheng Li, Jianfeng Wu, Jichun Wu and Bill X. Hu

Separations 2023, 10(2), 123; https://doi.org/10.3390/separations10020123 - 9 Feb 2023

Cited by 7 | Viewed by 2630

Abstract

Polyamide (PA) and bisphenol A (BPA) are selected as typical microplastic and endocrine-disrupting chemicals in this study. The adsorption of BPA on the surface of PA and the effect of PA on the transport behavior of BPA in groundwater are systematically investigated using [...] Read more.

Polyamide (PA) and bisphenol A (BPA) are selected as typical microplastic and endocrine-disrupting chemicals in this study. The adsorption of BPA on the surface of PA and the effect of PA on the transport behavior of BPA in groundwater are systematically investigated using a combination of batch experiments, column experiments and numerical models. The results of scanning electron microscope (SEM) and Fourier transform infrared spectra (FTIR) show that the surface of PA particles is changed significantly after adsorption of BPA. The isothermal adsorption process of BPA can be simulated by the Langmuir model and the Freundlich model. Kinetic adsorption, on the other hand, can be fitted by a quasi-first-order adsorption model, and the adsorption results indicate that the maximum adsorption of BPA on PA reaches 13 mg·g⁻¹. The results of the column experiments suggest that the mass recovery rate of BPA decreases with PA content, and increases with flow velocity, while initial concentration has no apparent influence on BPA transport. In addition, due to the hydrolysis of BPA, the mass recovery rate of BPA does not change with pH under conditions of pH < 10.2 and increases substantially to 94% when pH > 10.2. Moreover, Ca²⁺ has a significant inhibitory effect on the transport of BPA, while Na⁺ has no apparent influence on the transport of BPA. The transport process of BPA in porous media is simulated using a single-point kinetic model, and the fitted mathematical relationships for the variation of kinetic parameters with environmental factors are obtained by regression analysis. Full article

(This article belongs to the Special Issue Separation Processes for Effective Removal of Emerging Contaminants from Water and Wastewater)

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18 pages, 4690 KiB

Open AccessArticle

Development of Micro-Column Preconcentration Method Using a Restricted-Access Poly(protoporphyrin-co-vinyl pyridine) Adsorbent for Copper Determination in Water and Milk Samples by FIA-FAAS

by Fabio Antonio Cajamarca Suquila, Letícia Alana Bertoldo, Eduardo Lins and César Ricardo Teixeira Tarley

Separations 2023, 10(2), 122; https://doi.org/10.3390/separations10020122 - 9 Feb 2023

Cited by 4 | Viewed by 2350

Abstract

For years, researchers have focused on the determination of metal ions at trace levels in environmental and food samples using analytical methods that employ techniques with low cost acquisition and maintenance and without microwave-assisted acid digestion procedures or aggressive reagents. Therefore, the present [...] Read more.

For years, researchers have focused on the determination of metal ions at trace levels in environmental and food samples using analytical methods that employ techniques with low cost acquisition and maintenance and without microwave-assisted acid digestion procedures or aggressive reagents. Therefore, the present study deals with the synthesis and application of a novel, restricted-access poly(protoporphyrin-co-vinyl pyridine) adsorbent to preconcentrate copper in water samples and bovine milk that have only been subjected to pH adjusting (pH 6.0) and filtration using posterior on-line determination by FAAS. Regarding macromolecules, the restricted-access property of the adsorbent was achieved using the hydrophilic compound 2-hydroxyethyl methacrylate (HEMA). This method is based on the preconcentration of Cu²⁺ ions using a flow-injection system which is buffered with 0.05 mol L⁻¹ of Britton–Robinson (BR) at a pH of 6.0 and has a flow rate of 14.0 mL min⁻¹ through a mini-column packed with 50.0 mg of adsorbent. The elution was carried out using 0.40 mol L⁻¹ of HCl toward the FAAS detector. The developed method provided a preconcentration factor of 44.7-fold, low limits of detection (LOD) (0.90 µg L⁻¹) and quantification (LOQ) (2.90 µg L⁻¹), tolerance to interfering ions (95.0 and 103.0%), and intra-day and inter-day precision assessed as the RSD (percentage of relative standard deviation), which ranged from 3.08 to 4.80%. The restricted-access poly(protoporphyrin-co-vinyl pyridine) adsorbent demonstrated outstanding features to exclude macromolecules, bovine serum albumin (BSA), and humic acid (HA) from an aqueous medium. Lake water and bovine milk samples were analyzed by the proposed preconcentration method with minimal sample pretreatment (which was based mainly on pH adjusting and filtration using an analytical curve with external calibration), yielding recovery values from addition and recovery tests ranging from 91.7 to 101.9%. The developed method shows great advantages over previously published methods, avoiding the time-consuming use of concentrated acids in a microwave-assisted acid digestion procedure. Full article

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25 pages, 1744 KiB

Open AccessReview

Green Extraction Techniques for the Determination of Active Ingredients in Tea: Current State, Challenges, and Future Perspectives

by Ioulia Maria Koina, Yiannis Sarigiannis and Evroula Hapeshi

Separations 2023, 10(2), 121; https://doi.org/10.3390/separations10020121 - 9 Feb 2023

Cited by 22 | Viewed by 8675

Abstract

In recent years, the scientific community has turned its attention to the further study and application of green chemistry as well as to sustainable development in reducing the consumption of raw materials, solvents, and energy. The application of green chemistry aims to ensure [...] Read more.

In recent years, the scientific community has turned its attention to the further study and application of green chemistry as well as to sustainable development in reducing the consumption of raw materials, solvents, and energy. The application of green chemistry aims to ensure the protection of the environment and to also, consequently, improve the quality of human life. It offers several benefits, both socially and economically. In the last few decades, new alternative non-conventional green extraction methodologies have been developed for the purposes of the extraction of active ingredient compounds from various raw products. The main objective of this literature review is to present the current knowledge and future perspectives regarding the green extraction of tea species in respect of the isolation of safe active biomolecules, which can be used as commercially available products—both as dietary supplements and pharmaceutical formulations. More specifically, in this literature review, the intention is to investigate several different extraction techniques, such as ultrasonic-assisted extraction, ultrasonic-assisted extraction with DESs, the microwave assisted-extraction method, and the reflux method. These are presented in respect of their role in the isolation of bioactive molecules regarding different tea species. Furthermore, following the literature review conducted in this study, the commonly used green extraction methods were found to be the ultrasound-assisted method and the microwave-assisted method. In addition to these, the use of a green solvent, in regard to its role in the maximum extraction yield of active ingredients in various species of tea, was emphasized. Catechins, alkaloids (such as caffeine), gallic acid, and flavonoids were the main extracted bioactive molecules that were isolated from the several tea species. From this literature review, it can be demonstrated that green tea has been widely studied at a rate of 52% in respect of the included research studies, followed by black tea at 26%, as well as white tea and oolong tea at 11% each. Regarding the determination of the bioactive molecules, the most utilized analytical method was found in the combination of high-performance liquid chromatography (HPLC) with a photodiode array detector (PDA) and mass spectrophotometry (MS) at a usage rate of about 80%. This method was followed by the utilization of UPLC and GC at 12% and 8%, respectively. In the future, it will be necessary to study the combination of green extraction techniques with other industry strategies, such as an encapsulation at the micro and nano scale, for the purposes of preparing stable final products with antioxidant properties where, finally, they can be safely consumed by humans. Full article

(This article belongs to the Special Issue Women in Separations)

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2 pages, 187 KiB

Open AccessEditorial

Hydrophilic Interaction Chromatography

by Makoto Tsunoda

Separations 2023, 10(2), 120; https://doi.org/10.3390/separations10020120 - 9 Feb 2023

Viewed by 1366

Abstract

Hydrophilic interaction chromatography (HILIC) was first introduced by Alpert in 1990 [...] Full article

12 pages, 1138 KiB

Open AccessArticle

A Selective and Accurate LC-MS/MS Method for Simultaneous Quantification of Valsartan and Hydrochlorothiazide in Human Plasma

by Anzarul Haque, Muzaffar Iqbal, Mariam K. Alamoudi and Prawez Alam

Separations 2023, 10(2), 119; https://doi.org/10.3390/separations10020119 - 8 Feb 2023

Cited by 6 | Viewed by 2341

Abstract

The fixed dose combination of valsartan (VAL) and hydrochlorothiazide (HCTZ) is the most commonly prescribed medicine for the effective treatment of hypertension. In this study, a simple sensitive and accurate liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous quantitation of [...] Read more.

The fixed dose combination of valsartan (VAL) and hydrochlorothiazide (HCTZ) is the most commonly prescribed medicine for the effective treatment of hypertension. In this study, a simple sensitive and accurate liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous quantitation of VAL and HCTZ in human plasma by using irbesartan (IRB) and hydroflumethiazide (HFMZ) as their specific internal standards (ISs). HLB cartridge-based solid-phase extraction was used for the extraction of analytes and ISs. The chromatographic separation was achieved on Lichrocart RP Select (125 × 4 mm), 5 nm with the mobile phase composition of acetonitrile: 10 mM ammonium acetate buffer: 95:05, v/v, at flow rate of 0.5 mL/min. The turbo ion electrospray ionization in negative mode was used as ion source for the sample ionization. The precursor to product ion transitions were 434.10 > 179.10 (VAL), 295.70 > 204.90 (HCTZ), 427.10 > 192.90 (IRB), and 329.90 > 302.40 (HFMZ) for detection and quantification of analytes and their ISs. The retention times of VAL and HCTZ were 1.90 min and 2.30 min, respectively. The range for the calibration curves of VAL and HCTZ were 50.2–6018.6 ng/mL and 1.25–507.63 ng/mL, respectively, with good linearity having correlation coefficient values of ≥0.995 for both VAL and HCTZ. All validation parameter results (selectivity, precision and accuracy, matrix effects and stabilities) were within the acceptable range as per USFDA guideline for bioanalytical method validation. The intra-day and inter-day accuracy data for VAL were within the range of 105.68–114.22% and 98.41–108.16%, respectively, whereas for HCTZ they were 87.01–101.18% and 95.16–99.37%, respectively. The ion suppression effects produced for VAL and ion enhancement effects produced for HCTZ were insignificant according to the proposed sample cleanup procedure. The developed LC-MS/MS method was successfully applied to bioequivalence study on healthy volunteers. Full article

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14 pages, 2051 KiB

Open AccessArticle

Sustainable Microwave-Assisted Extraction of Santalin from Red Sandal Wood Powder (Ptrecarpus santalinus) for Bio-Coloration of Mordanted Silk Fabric

by Samra Barkaat, Maria Mehboob, Shahid Adeel, Fazal-ur-Rehman, Nimra Amin, Noman Habib and Mozhgan Hosseinnezhad

Separations 2023, 10(2), 118; https://doi.org/10.3390/separations10020118 - 7 Feb 2023

Cited by 11 | Viewed by 2009

Abstract

The coloring behavior of santalin, a natural reddish-brown dye derived from sandalwood, has been investigated in this work for the dyeing of silk fabrics while being heated in MW radiation. Microwave (MW) radiation up to 5 min has been employed to isolate colorant [...] Read more.

The coloring behavior of santalin, a natural reddish-brown dye derived from sandalwood, has been investigated in this work for the dyeing of silk fabrics while being heated in MW radiation. Microwave (MW) radiation up to 5 min has been employed to isolate colorant (Santalin) from red sandalwood (Ptrecarpus santalinus) in selected medium, and bio-mordants in competing with salts as chemical-mordants have been included. Statistical analysis was made and dyeing variables were selected for getting dark shades though mordants. MW treatment for 3 min. to both extract and fabric was selected and mild dyeing conditions were optimized statistically to get dark shades. On applying chemical mordants, selected amount of salts of Al⁺³, Fe⁺² and T.A. before and after dyeing, has given good results. Comparatively, selected extracts of plant based sources have shown colorfast shades of high strength. The MW radiation has excellent potential to extract dye form plants using optimum medium through less time and energy, and the application of plant extracts along with sustainable salts have developed colorfast shades. Full article

(This article belongs to the Special Issue Extraction and Component Analysis of Active Ingredients from Natural Products)

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15 pages, 3648 KiB

Open AccessArticle

Just Suspended Speed Simulation in Torus Reactor Using Multiple Non-Linear Regression Model

by Houssem Eddine Sayah, Ali Alouache, Mohamed Annad, Abdelouahab Lefkir, L’hadi Nouri, Ammar Selatnia and Mohammed Messaoudi

Separations 2023, 10(2), 117; https://doi.org/10.3390/separations10020117 - 7 Feb 2023

Viewed by 1569

Abstract

In the chemical and water treatment industries, it is necessary to achieve maximum contact between the solid and liquid phase, thus promoting the mass and heat transfer, to obtain a homogeneous solution. Increasing stirring speed is the most recommended solution in different types [...] Read more.

In the chemical and water treatment industries, it is necessary to achieve maximum contact between the solid and liquid phase, thus promoting the mass and heat transfer, to obtain a homogeneous solution. Increasing stirring speed is the most recommended solution in different types of reactors: stirred tank, column, and tubular. However, this inadvertently increases the energy consumption of the industry. Determination of the minimum speed, labeled the just suspended speed (N_js) and crucial to attaining homogeneity, has been widely investigated. Numerous studies have been carried out to assess formulas for determining the solid particle speed in various reactor types. Given the limitations of the existing formulations based on a generalization of a unique equation for computing N_js for all soil classifications, it appears that most formulas can only approximate complex phenomena that depend on several parameters. A novel formula was developed, and the results given in this paper demonstrate the effectiveness of generating significant uncertainties for the estimation of N_js. The purpose of this study was the elaboration of experiment-based data-driven formulas to calculate N_js for different particle size classes. Nonlinear multiple regression (MNLR) models were used to generate the new formulas. The gradient descent optimization algorithm was employed to solve the hyperparameters of each novel equation, utilizing supervised learning. A comparison of the data indicated that the unique formulas presented in this study outperformed empirical formulas and provide a useful means for lowering energy consumption, while increasing the heat and mass transfer in torus type reactors. Full article

(This article belongs to the Special Issue Development and Application of Green or Sustainable Strategies in Analytical Chemistry Volume II)

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15 pages, 1210 KiB

Open AccessEditor’s ChoiceArticle

Investigation of Imidazolium-Based Ionic Liquids as Additives for the Separation of Urinary Biogenic Amines via Capillary Electrophoresis

by Natalia Kaczmarczyk, Natalia Treder, Piotr Kowalski, Alina Plenis, Anna Roszkowska, Tomasz Bączek and Ilona Olędzka

Separations 2023, 10(2), 116; https://doi.org/10.3390/separations10020116 - 7 Feb 2023

Cited by 2 | Viewed by 1522

Abstract

Ionic liquids (ILs), such as imidazoles, can be used to prevent the sorption of analytes onto the walls of the capillary. Prior works have confirmed that coating the capillary wall with a cationic layer can increase its surface stability, thereby improving the repeatability [...] Read more.

Ionic liquids (ILs), such as imidazoles, can be used to prevent the sorption of analytes onto the walls of the capillary. Prior works have confirmed that coating the capillary wall with a cationic layer can increase its surface stability, thereby improving the repeatability of the separation process. In this study, micellar electrokinetic chromatography (MEKC) is employed to evaluate how two ILs with different anions—namely, 1-hexyl-3-methylimidazolium chloride [HMIM⁺Cl⁻] and 1-hexyl-3-methylimidazolium tetrafluoroborate [HMIM⁺BF₄⁻]—affect the separation efficiency for biogenic amines (BAs) such as metanephrine (M), normetanephrine (NM), vanilmandelic acid (VMA), and homovanillic acid (HVA) in urine samples. To this end, solid-phase extraction (SPE) is employed using different sample pH values, with the results demonstrating that HVA and VMA is easily extracted at a sample pH of 5.5, while a sample pH of 9.0 facilitated the extraction of M and NM. In the applied SPE protocol, selected analytes were isolated from urine samples using hydrophilic–lipophilic-balanced (HLB) columns and eluted with methanol (MeOH). The validation data confirmed the method’s linearity (R² > 0.996) for all analytes within the range of 0.25–10 µg/mL. The applicability of the optimized SPE-MEKC-UV method was confirmed by employing it to quantify clinically relevant BAs in real urine samples from pediatric neuroblastoma (NBL) patients. Full article

(This article belongs to the Special Issue Ionic Liquids in Separation Technology)

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15 pages, 5263 KiB

Open AccessEditor’s ChoiceArticle

Preparation of Fe₃O₄-Reduced Graphene-Activated Carbon from Wastepaper in the Dispersive Solid-Phase Extraction and UHPLC-PDA Determination of Antibiotics in Human Plasma

by Pantaleone Bruni, Pasquale Avino, Vincenzo Ferrone, Serena Pilato, Nadia Barbacane, Valentino Canale, Giuseppe Carlucci and Stefania Ferrari

Separations 2023, 10(2), 115; https://doi.org/10.3390/separations10020115 - 7 Feb 2023

Cited by 2 | Viewed by 1788

Abstract

In this work, a sorbent was prepared from wastepaper samples enriched with iron oxide particles and graphene oxide and used in the solid phase extraction of antibiotics. The precursor underwent a carbothermal reduction to promote the formation of paramagnetic phases useful for the [...] Read more.

In this work, a sorbent was prepared from wastepaper samples enriched with iron oxide particles and graphene oxide and used in the solid phase extraction of antibiotics. The precursor underwent a carbothermal reduction to promote the formation of paramagnetic phases useful for the recovery of the sorbent during the analysis, and to disperse and fix graphene and the iron oxide in a durable way throughout the cellulose structure. Characterizations were carried out to evaluate the composition (Raman, XRD and EDX) and the morphological structure (SEM) of the material. A UHPLC-PDA method was developed for the simultaneous determination of antibiotics from different drug families (carbapenems, fluoroquinolones, β-lactams) using a 120 SB-C 18 poroshell column (50 × 2.1 mm I.D., 2.7 um particle size) and a mobile phase consisting of 10 mM acetate buffer at pH 5 (Line A) and acetonitrile (Line B) both containing 0.1% of triethylamine. A gradient elution was used for the separation of the analytes, while for the quantitative analysis each analyte was determined at its maximum wavelength. Several experiments were carried out to evaluate the influence of different parameters involving the dispersive magnetic solid phase extraction of these analytes. Samples were extracted using 25 mg of sorbent at pH 5 and desorbed in 5 min using methanol. We report herein on some of the outstanding advantages of using carbon-based sorbent, such as lower toxicity, scalability, improved absorption capacity, target selectivity and stability in acidic medium. Moreover, from the results obtained it is evident that, despite the use of some recycled materials, the performances obtained were comparable or even superior to the methods reported in the literature. Full article

(This article belongs to the Special Issue Recent Advances in Microextraction Technology for Analytical Sample Preparation)

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