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Separations
Volume 7
Issue 2
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Separations, Volume 7, Issue 2 (June 2020) – 17 articles

Cover Story (view full-size image): Fourier transform infrared spectroscopy (FTIR) complements mass spectrometry (MS), where both techniques offer their own particular molecular characterisation specificity for identification of eluted compounds in gas chromatography (GC). Both FTIR and MS are orthogonal experimental tools; the fine molecular spectroscopic details of structural features and functional group arrangements in FTIR are contrasted by information of molecular ions and fragmentation in MS. GC‒MS is considered the ‘gold standard’ approach for compound characterisation but often cannot provide unambiguous identification; this includes many isomers, and compounds of similar structures such as α- and β-pinene in essential oils. In contrast, GC‒FTIR offers molecular specificity that often escapes that of MS. Here, we re-visit GC‒FTIR and highlight novel approaches and selected advantages of this valuable technique. View this paper.
Fourier transform infrared spectroscopy (FTIR) complements mass spectrometry (MS), where both techniques offer their own particular molecular characterisation specificity for identification of eluted compounds in gas chromatography (GC). Both FTIR and MS are orthogonal experimental tools; the fine molecular spectroscopic details of structural features and functional group arrangements in FTIR are contrasted by information of molecular ions and fragmentation in MS. GC‒MS is considered the ‘gold standard’ approach for compound characterisation but often cannot provide unambiguous identification; this includes many isomers, and compounds of similar structures such as α- and β-pinene in essential oils. In contrast, GC‒FTIR offers molecular specificity that often escapes that of MS. Here, we re-visit GC‒FTIR and highlight novel approaches and selected advantages of this valuable technique.
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27 pages, 3592 KiB  
Review
Recent Advances in the Analysis of Vitamin D and Its Metabolites in Food Matrices
by Bárbara Socas-Rodríguez, Margareta Sandahl, Cecilia Holm and Charlotta Turner
Separations 2020, 7(2), 36; https://doi.org/10.3390/separations7020036 - 24 Jun 2020
Cited by 6 | Viewed by 5591
Abstract
Vitamin D and its analogues are fat-soluble vitamins that carry out important functions in human and animal organisms. Many studies have pointed out the relationship between the deficiency of these substances and the development of both skeletal- and extra-skeletal diseases. Although vitamin D [...] Read more.
Vitamin D and its analogues are fat-soluble vitamins that carry out important functions in human and animal organisms. Many studies have pointed out the relationship between the deficiency of these substances and the development of both skeletal- and extra-skeletal diseases. Although vitamin D is fundamentally derived from the bio-transformation of its precursor, 7-dehydrocholesterol, through the action of UV-B radiation in the skin, dietary intake also plays an important role in the regulation of its status in an organism. For this reason, the application of reliable methodologies that enable monitoring the content of vitamin D and its analogues in food and supplements constitutes an aspect of special relevance to establish adequate habits, which avoid the deficiency of these substances in organisms and, consequently, the appearance of related diseases. The use of chromatographic techniques in combination with conventional and novel sample pre-treatments has become a suitable strategy to achieve this aim. This review compiles the most relevant methodologies reported in the last ten years for vitamin D analogues analysis in food matrices. Particular attention has been paid to provide a general overview of the most suitable approaches in terms of reliability, sensitivity and simplicity, used in the field of food analysis. Full article
(This article belongs to the Special Issue Applications of Chromatographic Techniques in Food and Environmental Analysis)
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12 pages, 1302 KiB  
Article
GC-MS Analysis and Hemolytic, Antipyretic and Antidiarrheal Potential of Syzygium aromaticum (Clove) Essential Oil
by Cristiane Marinho Uchôa Lopes, João Ricardhis Saturnino de Oliveira, Vanderlan Nogueira Holanda, Antonio Yony Felipe Rodrigues, Caíque Silveira Martins da Fonseca, Fábio Fernandes Galvão Rodrigues, Cicera Janaine Camilo, Vera Lucia de Menezes Lima, Henrique Douglas Melo Coutinho, Radosław Kowalski and José Galberto Martins da Costa
Separations 2020, 7(2), 35; https://doi.org/10.3390/separations7020035 - 19 Jun 2020
Cited by 13 | Viewed by 5832
Abstract
Clove (Syzygium aromaticum) is a spice widely used for its medical properties, though the species lacks scientific evidence regarding its toxicity and biologic effects. The aim of this study was the chemical identification by GC-MS analysis and evaluation of the hemolytic, [...] Read more.
Clove (Syzygium aromaticum) is a spice widely used for its medical properties, though the species lacks scientific evidence regarding its toxicity and biologic effects. The aim of this study was the chemical identification by GC-MS analysis and evaluation of the hemolytic, anticoagulant, antidiarrheal and antipyretic activities of the essential oil from S. aromaticum (EOSa) in adult male mice. Essential oil was obtained by hydrodistillation and provided 9.8% v/w yield. GC-MS analyses allowed the identification of nine constituents, with eugenol (84.63%) as the majority. EOSa was diluted in several concentrations (0.005–2 mg/mL) for hemolytic assays, showing hemolytic activity above 20% in concentrations higher than 0.625 mg/mL. Different concentrations of EOSa induced a coagulation time 100% higher than control blood. 50 and 100 mg/kg of EOSa caused additional intestinal motility induced by castor oil by 90–100%. Fever, induced by Saccharomyces cerevisae 15% (s.c.), was controlled by 50 and 100 mg/kg EOSa (p.o.), effects similar to 100 mg/kg dypirone. Results showed that when used orally, EOSa may have a certain degree of toxicity in high dosages, but with antipyretic and intestinal motility properties. Full article
(This article belongs to the Section Analysis of Natural Products and Pharmaceuticals)
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4 pages, 196 KiB  
Editorial
Advances in Solid-Phase Microextraction
by Attilio Naccarato and Antonio Tagarelli
Separations 2020, 7(2), 34; https://doi.org/10.3390/separations7020034 - 12 Jun 2020
Viewed by 2842
Abstract
Analysis imposes substantial challenges, especially when dealing with analytes present at trace levels in complex matrices [...] Full article
(This article belongs to the Special Issue Advances in Solid-Phase Microextraction)
14 pages, 896 KiB  
Article
Pigments Content (Chlorophylls, Fucoxanthin and Phycobiliproteins) of Different Commercial Dried Algae
by Catarina Osório, Susana Machado, Juliana Peixoto, Sílvia Bessada, Filipa B. Pimentel, Rita C. Alves and M. Beatriz P. P. Oliveira
Separations 2020, 7(2), 33; https://doi.org/10.3390/separations7020033 - 11 Jun 2020
Cited by 107 | Viewed by 13763
Abstract
Algae are a complex, polyphyletic group of organisms, affordable and naturally rich in nutrients, but also valuable sources of structurally diverse bioactive substances such as natural pigments. The aim of this work was to evaluate the polar and non-polar pigment contents of different [...] Read more.
Algae are a complex, polyphyletic group of organisms, affordable and naturally rich in nutrients, but also valuable sources of structurally diverse bioactive substances such as natural pigments. The aim of this work was to evaluate the polar and non-polar pigment contents of different commercial dried algae (brown: Himanthalia elongata, Undaria pinnatifida, Laminaria ochroleuca; red: Porphyra spp.; and a blue-green microalga: Spirulina spp.). The pigment extraction was carried out using different solvents (100% methanol, 100% methanol acid free, 100% ethanol, 90% acetone, N,N-dimethylformamide, dimethyl sulfoxide-water (4:1, v/v) and pH 6.8 phosphate buffer), selected according to their affinity for each class of pigments. Acetone proved to be an efficient solvent to extract chlorophylls from brown and red algae, but not from Spirulina spp. Porphyra spp. presented considerably higher levels of all pigments compared to brown algae, although Spirulina spp. presented significantly higher (p < 0.05) levels of chlorophylls, carotenoids and phycobiliproteins, compared to all macroalgae. The content of fucoxanthin extracted from the three brown algae was highly correlated to the carotenoid content. Within this group, Himanthalia elongata presented the highest fucoxanthin/total carotenoids ratio. Although the yield of extraction depended on the solvent used, the algae studied herein are an interesting source of pigments of great value for a wide range of applications. Full article
(This article belongs to the Special Issue Extraction and Isolation of Natural Products)
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13 pages, 2663 KiB  
Article
Non-Targeted Ultra-High Performance Liquid Chromatography-High-Resolution Mass Spectrometry (UHPLC-HRMS) Fingerprints for the Chemometric Characterization and Classification of Turmeric and Curry Samples
by Nerea Núñez, Oscar Vidal-Casanella, Sonia Sentellas, Javier Saurina and Oscar Núñez
Separations 2020, 7(2), 32; https://doi.org/10.3390/separations7020032 - 10 Jun 2020
Cited by 5 | Viewed by 4414
Abstract
In this work, non-targeted ultra-high performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) fingerprints obtained by C18 reversed-phase chromatography were proposed as sample chemical descriptors for the characterization and classification of turmeric and curry samples. A total of 21 turmeric and 9 curry commercially available [...] Read more.
In this work, non-targeted ultra-high performance liquid chromatography-high-resolution mass spectrometry (UHPLC-HRMS) fingerprints obtained by C18 reversed-phase chromatography were proposed as sample chemical descriptors for the characterization and classification of turmeric and curry samples. A total of 21 turmeric and 9 curry commercially available samples were analyzed in triplicate after extraction with dimethyl sulfoxide (DMSO). The results demonstrated the feasibility of non-targeted UHPLC-HRMS fingerprints for sample classification, showing very good classification capabilities by partial least squares regression-discriminant analysis (PLS-DA), with 100% classification rates being obtained by PLS-DA when randomly selected samples were processed as “unknown” ones. Besides, turmeric curcuma species (Curcuma longa vs. Curcuma zedoaria) and turmeric Curcuma longa varieties (Madras, Erodes, and Alleppey) discrimination was also observed by PLS-DA when using the proposed fingerprints as chemical descriptors. As a conclusion, non-targeted UHPLC-HRMS fingerprinting is a suitable methodology for the characterization, classification, and authentication of turmeric and curry samples, without the requirement of using commercially available standards for quantification nor the necessity of metabolite identification. Full article
(This article belongs to the Special Issue Applications of Chromatographic Techniques in Food and Environmental Analysis)
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4 pages, 176 KiB  
Editorial
Development of Alternative Green Sample Preparation Techniques
by Emanuela Gionfriddo
Separations 2020, 7(2), 31; https://doi.org/10.3390/separations7020031 - 4 Jun 2020
Cited by 7 | Viewed by 2894
Abstract
Although chemistry disciplines are often regarded by the public as polluting sciences, in the last three decades, the concept of “Green Chemistry” has fueled the development of more sustainable and environmentally friendly chemical processes that are mainly aimed at minimizing the production of [...] Read more.
Although chemistry disciplines are often regarded by the public as polluting sciences, in the last three decades, the concept of “Green Chemistry” has fueled the development of more sustainable and environmentally friendly chemical processes that are mainly aimed at minimizing the production of toxic laboratory waste, to maximize pollution prevention [...] Full article
(This article belongs to the Special Issue Development of Alternative Green Sample Preparation Techniques)
13 pages, 1170 KiB  
Article
Hydrophilic Liquid Chromatography versus Reversed-Phase Liquid Chromatography in the Absence and the Presence of 1-Hexyl-3-methylimidazolium Chloride for the Analysis of Basic Compounds
by Ester Peris-García, Raquel Burgos-Gil, María Celia García-Alvarez-Coque and María José Ruiz-Angel
Separations 2020, 7(2), 30; https://doi.org/10.3390/separations7020030 - 29 May 2020
Cited by 5 | Viewed by 3443
Abstract
In reversed-phase liquid chromatography (RPLC), positively charged basic compounds yield broad and asymmetric peaks, as a result of ionic interactions with free silanols that remain on conventional silica-based columns. Diverse solutions have been proposed to mask the silanophilic activity, which is translated to [...] Read more.
In reversed-phase liquid chromatography (RPLC), positively charged basic compounds yield broad and asymmetric peaks, as a result of ionic interactions with free silanols that remain on conventional silica-based columns. Diverse solutions have been proposed to mask the silanophilic activity, which is translated to an improved peak shape. In this work, the chromatographic performance of hydrophilic interaction liquid chromatography (HILIC) was evaluated as an alternative to the addition of an ionic liquid (IL) to the aqueous-organic mobile phase used with RPLC columns, for the analysis of eight β-adrenoceptor antagonists. ILs change the behavior of RPLC stationary phases owing to adsorption on their surface. Meanwhile, in HILIC, a layer of adsorbed water is formed on the stationary phase surface. The association of cationic basic compounds with the adsorbed additive ions, hydrophilic partitioning on the HILIC columns, and other interactions, give rise to complex retention mechanisms. The chromatographic behavior was examined in terms of retention, elution strength, selectivity, peak shape and resolution, using acetonitrile-water mobile phases buffered at pH 3. Both chromatographic modes, RPLC with added IL and HILIC, proved to be a viable solution to the problem of poor peak shape for basic compounds. Full article
(This article belongs to the Special Issue Recent Advances on Ionic Liquid Uses in Separation Techniques)
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18 pages, 319 KiB  
Review
Current Trends in Simultaneous Determination of Co-Administered Drugs
by Christian Celia, Luisa Di Marzio, Marcello Locatelli, Piera Ramundo, Francesca D’Ambrosio and Angela Tartaglia
Separations 2020, 7(2), 29; https://doi.org/10.3390/separations7020029 - 28 May 2020
Cited by 11 | Viewed by 5410
Abstract
Recently, high demand of high-throughput analyses with high sensitivity and selectivity to molecules and drugs in different classes with different physical-chemical properties—and a reduction in analysis time—is a principal milestone for novel methodologies that researchers are trying to achieve—especially when analytical procedures are [...] Read more.
Recently, high demand of high-throughput analyses with high sensitivity and selectivity to molecules and drugs in different classes with different physical-chemical properties—and a reduction in analysis time—is a principal milestone for novel methodologies that researchers are trying to achieve—especially when analytical procedures are applied to clinical purposes. In addition, to avoid high doses of a single drug that could cause serious side effects, multi-drug therapies are often used to treat numerous diseases. For these reasons, the demand for methods that allow the rapid analysis of mixed compounds has increased in recent years. In order to respond to these needs, new methods and instruments have been developed. However, often the complexity of a matrix can require a long time for the preparation and processing of the samples. Different problems in terms of components, types of matrices, compounds and physical-chemical complexity are encountered when considering drugs association profiles for quantitative analyses. This review addresses not only recently optimized procedures such as chromatographic separation, but also methods that have allowed us to obtain accuracy (precision and trueness), sensitivity and selectivity in quantitative analyses for cases of drug associations. Full article
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12 pages, 1137 KiB  
Article
Screening of Contaminants of Emerging Concern in Microalgae Food Supplements
by Isabel Martín-Girela, Beatriz Albero, Brijesh K. Tiwari, Esther Miguel and Ramón Aznar
Separations 2020, 7(2), 28; https://doi.org/10.3390/separations7020028 - 20 May 2020
Cited by 12 | Viewed by 3836
Abstract
The frenetic lifestyle in the developed countries has driven us to be deficient in some nutrients, which may be overcome by supplements. Microalgae, like spirulina (Arthrospira platensis) and chlorella (Chlorella ssp.) are widely used as supplements due to their high [...] Read more.
The frenetic lifestyle in the developed countries has driven us to be deficient in some nutrients, which may be overcome by supplements. Microalgae, like spirulina (Arthrospira platensis) and chlorella (Chlorella ssp.) are widely used as supplements due to their high contents of macro- and micronutrients. Chlorella and spirulina can be grown naturally in a range of water bodies, showing their high adaptability to harsh environments. They are mainly produced in countries with poor water quality and sometimes inexistent water legislation, which can be a vector of micropollutant introduction into the food chain. Thus, a method for the simultaneous determination of 31 emerging contaminants commonly found as micropollutants in freshwater (pharmaceutical and personal care products, hormones, flame retardants and biocides) in two microalgae is presented. Target contaminants were extracted from the microalgae employing ultrasound-assisted matrix solid-phase dispersion followed by gas chromatography-mass spectrometry analysis. The method was validated for chlorella and spirulina with recoveries ranging from 70% to 111% at concentrations of 25 and 100 ng·g−1, and good linearity in the range from 5 to 400 ng·g−1 with limits of detection below 2.5 ng·g−1, in both microalgae. The method validated was applied to a range of microalgae supplement foods and the results proved that the compounds studied were below limits of detection. Full article
(This article belongs to the Special Issue Analysis of Organic Micropollutants)
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16 pages, 2428 KiB  
Article
Relationships in Gas Chromatography—Fourier Transform Infrared Spectroscopy—Comprehensive and Multilinear Analysis
by Junaida Shezmin Zavahir, Jamieson S. P. Smith, Scott Blundell, Habtewold D. Waktola, Yada Nolvachai, Bayden R. Wood and Philip J. Marriott
Separations 2020, 7(2), 27; https://doi.org/10.3390/separations7020027 - 13 May 2020
Cited by 14 | Viewed by 5534
Abstract
Molecular spectroscopic detection techniques, such as Fourier transform infrared spectroscopy (FTIR), provides additional specificity for isomers where often mass spectrometry (MS) fails, due to similar fragmentation patterns. A hyphenated system of gas chromatography (GC) with FTIR via a light-pipe interface is reported in [...] Read more.
Molecular spectroscopic detection techniques, such as Fourier transform infrared spectroscopy (FTIR), provides additional specificity for isomers where often mass spectrometry (MS) fails, due to similar fragmentation patterns. A hyphenated system of gas chromatography (GC) with FTIR via a light-pipe interface is reported in this study to explore a number of GC–FTIR analytical capabilities. Various compound classes were analyzed—aromatics, essential oils and oximes. Variation in chromatographic peak parameters due to the light-pipe was observed via sequentially-located flame ionization detection data. Unique FTIR spectra were observed for separated mixtures of essential oil isomers having similar mass spectra. Presentation of GC×FTIR allows a ‘comprehensive’-style experiment to be developed. This was used to obtain spectroscopic/separation profiles for interconverting oxime species with their individual spectra in the overlap region being displayed on a color contour plot. Partial least square regression provides multivariate quantitative analysis of co-eluting cresol isomers derived from GC–FTIR data. The model resulted in an R2 of 0.99. Prediction was obtained with R2 prediction value of 0.88 and RMSEP of 0.57, confirming the method’s suitability. This study explores the potential of GC–FTIR hyphenation and re-iterates its value to derive unambiguous and detailed molecular information which is complementary to MS. Full article
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9 pages, 2904 KiB  
Article
Analysis of Organic Sulphur Compounds in Coal Tar by Using Comprehensive Two-Dimensional Gas Chromatography-High Resolution Time-of-Flight Mass Spectrometry
by Ivan Aloisi, Mariosimone Zoccali, Peter Q. Tranchida and Luigi Mondello
Separations 2020, 7(2), 26; https://doi.org/10.3390/separations7020026 - 9 May 2020
Cited by 4 | Viewed by 4215
Abstract
Coal tar is a complex mixture of organic compounds obtained from the thermal treatment of coal; it contains several different chemical classes of compounds, such as polycyclic aromatic hydrocarbons, phenols and different heterocyclic compounds including sulphur derivatives. In the present research, a target [...] Read more.
Coal tar is a complex mixture of organic compounds obtained from the thermal treatment of coal; it contains several different chemical classes of compounds, such as polycyclic aromatic hydrocarbons, phenols and different heterocyclic compounds including sulphur derivatives. In the present research, a target analysis was carried out for the characterisation of fourteen different classes of organic sulphur compounds in coal tar by using cryogenically-modulated (CM) comprehensive two-dimensional gas chromatography-high resolution time-of-flight mass spectrometry (GC×GC-HR ToFMS) with the support of target analyte finding, a specific software function. Furthermore, absolute quantification data were obtained by using eight pure standard sulphur compounds, and 1-fluoronaphthalene as internal standard. Several figures-of-merit of the proposed method were measured (linearity, intra-day precision, limits of detection and quantification). Finally, the overall analytical performance of CM GC×GC-HR ToFMS was evaluated, in relation to MS similarities, mass accuracies, second-dimension peak widths, peak capacity and tailing factors. The approach proved itself as being a powerful analytical platform, benefiting from the high sensitivity, selectivity and resolving power, of both the GC and MS sides. Full article
(This article belongs to the Special Issue Multidimensional Chromatography)
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12 pages, 3362 KiB  
Article
Comparison of Online Comprehensive HILIC × RP and RP × RP with Trapping Modulation Coupled to Mass Spectrometry for Microalgae Peptidomics
by Eduardo Sommella, Emanuela Salviati, Simona Musella, Veronica Di Sarno, Francesco Gasparrini and Pietro Campiglia
Separations 2020, 7(2), 25; https://doi.org/10.3390/separations7020025 - 30 Apr 2020
Cited by 11 | Viewed by 3394
Abstract
In this work, two online comprehensive two-dimensional liquid chromatography platforms, namely Hydrophilic interaction liquid chromatography × Reversed phase (HILIC × RP) and Reversed phase × Reversed Phase (RP × RP) coupled to mass spectrometry, were compared for the analysis of complex peptide samples. [...] Read more.
In this work, two online comprehensive two-dimensional liquid chromatography platforms, namely Hydrophilic interaction liquid chromatography × Reversed phase (HILIC × RP) and Reversed phase × Reversed Phase (RP × RP) coupled to mass spectrometry, were compared for the analysis of complex peptide samples. In the first dimension, a HILIC Amide and C18 Bioshell peptide (150 × 2.1 mm, 1.7 and 2.0 μm) columns were selected, while, in the second dimension, a short C18 (50 × 3.0 mm, 2.7 μm) Bioshell peptide column was used. Two C18 trapping columns (10 × 3.0 mm, 1.9 μm), characterized by high retention and surface area, were employed as modulation interface in both HILIC × RP and RP × RP methods. The LC × LC platforms were coupled to UV and tandem mass spectrometry detection and tested for the separation and identification of two gastro-intestinal digests of commercial microalgae formulations (Spirulina Platensis and Klamath). Their performances were evaluated in terms of peak capacity, maximum number and properties of identified phycocyanin peptides. Our results showed that the HILIC × RP approach provided the highest peak capacity values (nc HILIC × RP: 932 vs. nc RP × RP: 701) with an analysis time of 60 min, while the RP × RP approach was able to identify a slight higher number of phycocyanin derived peptides (HILIC × RP: 88 vs. RP × RP: 103). These results point out the flexibility and potential of HILIC × RP and RP × RP based on trapping modulation for peptide mapping approaches. Full article
(This article belongs to the Special Issue Multidimensional Chromatography)
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13 pages, 3545 KiB  
Article
The Use of Natural Minerals in a Pilot-Scale MBR for Membrane Fouling Mitigation
by Petros Gkotsis, Efrosini Peleka and Anastasios Zouboulis
Separations 2020, 7(2), 24; https://doi.org/10.3390/separations7020024 - 23 Apr 2020
Cited by 10 | Viewed by 3056
Abstract
This study examines the effect of bentonite and zeolite concentration (0.25–5 g/L) on the membrane fouling of a fully automated, pilot-scale membrane bioreactor (MBR) treating high-strength synthetic municipal wastewater. Reversible fouling was estimated by sludge filterability measurements and irreversible fouling was estimated by [...] Read more.
This study examines the effect of bentonite and zeolite concentration (0.25–5 g/L) on the membrane fouling of a fully automated, pilot-scale membrane bioreactor (MBR) treating high-strength synthetic municipal wastewater. Reversible fouling was estimated by sludge filterability measurements and irreversible fouling was estimated by the reduction of the carbohydrate fraction of soluble microbial products (SMPc), which are considered to be significant MBR foulants. Both minerals were added to biomass samples (during batch-mode experiments) which were obtained from the system’s aeration tank. Results showed that the optimal bentonite and zeolite concentrations were 3.5–4 g/L and 2.5–3.5 g/L, respectively. Interestingly, above these values, the addition of both minerals increased the examined fouling indices, i.e., the measured filterability times and the SMPc concentration, implying that they might act as foulants at high concentrations. Optical microscopy images of the biomass samples showed that the addition of minerals at the optimal concentrations did not affect significantly filamentous microorganisms, since filament index (FI) was practically unaffected (~2). Finally, regarding the system’s treating performance, it was found that the pilot-scale MBR can operate successfully with high-strength synthetic municipal wastewater, since remarkable behaviour was exhibited in terms of organics (BOD5, COD) and ammonium (NH4+-N) removal (>98%). Full article
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13 pages, 2533 KiB  
Article
Characterization of Turmeric and Curry Samples by Liquid Chromatography with Spectroscopic Detection Based on Polyphenolic and Curcuminoid Contents
by Oscar Vidal-Casanella, Nerea Nuñez, Sonia Sentellas, Oscar Núñez and Javier Saurina
Separations 2020, 7(2), 23; https://doi.org/10.3390/separations7020023 - 21 Apr 2020
Cited by 11 | Viewed by 5031
Abstract
This paper deals with the characterization of turmeric and related products using the compositional fingerprints of curcuminoids (e.g., curcumin, demethoxycurcumin and bisdemethoxycurcumin) and other phenolic compounds (e.g., hydroxybenzoic and hydroxycinnamic acids and flavonoids) as the source of analytical information. Under this approach, the [...] Read more.
This paper deals with the characterization of turmeric and related products using the compositional fingerprints of curcuminoids (e.g., curcumin, demethoxycurcumin and bisdemethoxycurcumin) and other phenolic compounds (e.g., hydroxybenzoic and hydroxycinnamic acids and flavonoids) as the source of analytical information. Under this approach, the quantitative determination of analytes becomes unnecessary and even data from unknown components can be advantageously exploited for sample exploration and authentication. The methodology relied on sample extraction with hydro-organic solvents to recover the components of interest and further analysis of the corresponding extracts by liquid chromatography with diode array detection (HPLC-DAD). Extraction conditions were optimized focusing on the independent recovery of curcuminoids and polyphenols. Two different HPLC methods under reversed-phase mode were used to generate the chromatographic fingerprints at 420 and 280 nm for the specific monitoring of curcuminoids and polyphenols, respectively. Both extraction and separation steps were optimized under experimental design approaches to achieve the richest compositional fingerprints in terms of variety of components. The resulting data was subsequently treated chemometrically by principal component analysis (PCA) and related classification methods to achieve a better overall description of samples. Polyphenolic fingerprints were appropriate to discriminate among turmeric and mixed spices, while curcuminoid fingerprints could be useful to distinguish turmeric varieties. Full article
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18 pages, 3313 KiB  
Article
From Coffee to Biodiesel—Deep Eutectic Solvents for Feedstock and Biodiesel Purification
by Aleksandra Sander, Ana Petračić, Jelena Parlov Vuković and Lana Husinec
Separations 2020, 7(2), 22; https://doi.org/10.3390/separations7020022 - 18 Apr 2020
Cited by 19 | Viewed by 4310
Abstract
Over three billion cups of coffee are consumed daily, making waste coffee grounds readily available throughout the world. Containing approximately 10–15 wt% of oil, they have great potential for biodiesel production. The goal of this work was to produce high quality biodiesel from [...] Read more.
Over three billion cups of coffee are consumed daily, making waste coffee grounds readily available throughout the world. Containing approximately 10–15 wt% of oil, they have great potential for biodiesel production. The goal of this work was to produce high quality biodiesel from waste coffee grounds. One fresh and four different types of waste coffee grounds were collected. Oil was extracted by the Soxhlet method with n-hexane and then purified via extractive deacidification with a potassium carbonate-based deep eutectic solvent. Biodiesels were synthesized by means of alkali catalyzed transesterification at different catalyst:methanol:oil mass ratios and reaction times. Impurities present in crude biodiesels were extracted with a choline chloride-based deep eutectic solvent. All batch extraction experiments were performed at room conditions in a small scale extractor. Optimal conditions for synthesis and purification were defined in order to assure high quality of the produced biodiesel. Additionally, continuous column extraction with the choline chloride-based solvent was tested as a purification method for crude biodiesel. Stabilization time and optimal biodiesel to solvent mass ratio were determined. The potassium carbonate-based solvent efficiently reduced the total acid number of the feedstock (deacidification efficiency ranged from 86.18 to 94.15%), while the one based on choline chloride removed free glycerol and glycerides from crude biodiesels. After continuous purification, the purified biodiesel was of excellent quality with glycerol and glyceride contents below the EN 14214 limit. Full article
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11 pages, 614 KiB  
Article
Extraction of Phthalic Acid Esters and Di(2-ethylhexyl) Adipate from Tap and Waste Water Samples Using Chromabond® HLB as Sorbent Prior to Gas Chromatography-Mass Spectrometry Analysis
by Cecilia Ortega-Zamora, Javier González-Sálamo, Diana Angélica Varela-Martínez, Miguel Ángel González-Curbelo and Javier Hernández-Borges
Separations 2020, 7(2), 21; https://doi.org/10.3390/separations7020021 - 10 Apr 2020
Cited by 4 | Viewed by 3955
Abstract
In this work, Chromabond® HLB was evaluated as an extraction sorbent of a group of seven phthalic acid esters (PAEs; i.e., dipropyl phthalate, DPP, dibutyl phthalate, DBP, diisopentyl phthalate, DIPP, di-n-pentyl phthalate, DNPP, butylbenzyl phthalate, BBP, dicyclohexyl phthalate, DCHP, and di(2-ethylhexyl)phthalate, DEHP) [...] Read more.
In this work, Chromabond® HLB was evaluated as an extraction sorbent of a group of seven phthalic acid esters (PAEs; i.e., dipropyl phthalate, DPP, dibutyl phthalate, DBP, diisopentyl phthalate, DIPP, di-n-pentyl phthalate, DNPP, butylbenzyl phthalate, BBP, dicyclohexyl phthalate, DCHP, and di(2-ethylhexyl)phthalate, DEHP) and one adipate (di(2-ethylhexyl) adipate, DEHA) from tap and waste water prior to gas chromatography-mass spectrometry. After the optimization of the extraction conditions (200 mg of sorbent conditioned with 10 mL of acetonitrile and 2 mL of Milli-Q water, extraction of 50 mL of water at pH 6.0, vacuum drying for 20 min and elution with 10 mL of ethyl acetate), a recovery study was developed at different concentration levels in each matrix, which revealed that most of the target analytes could be recovered between 75 and 112%, with relative standard deviation values for all of them below 20%. Matrix effect was evaluated, finding that matrix-matched calibration should be developed for most analytes in both matrices. The limits of quantification (LOQs) of the method were in the 0.82–71 ng L−1 range. The developed method was also applied to the extraction of the target PAEs in different water samples finding some of them, in particular, DNPP in tap water samples, and BBP and DCHP in waste water, but below the LOQs of the method. Full article
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15 pages, 3060 KiB  
Article
Study of the Kinetics of Extraction Process for The Production of Hemp Inflorescences Extracts by Means of Conventional Maceration (CM) and Rapid Solid-Liquid Dynamic Extraction (RSLDE)
by Monica Gallo, Andrea Formato, Martina Ciaravolo, Gaetano Formato and Daniele Naviglio
Separations 2020, 7(2), 20; https://doi.org/10.3390/separations7020020 - 30 Mar 2020
Cited by 13 | Viewed by 9192
Abstract
In the present work, the kinetics of the extraction process from female inflorescences of Canapa sativa subsp. sativa var. sativa were studied, on the basis of determination of the content of cannabinoids: cannabidiolic acid (CBDA), Δ9-tetrahydrocannabinolic acid (THCA), cannabidiol (CBD) and Δ9-tetrahydrocannabinol (THC), [...] Read more.
In the present work, the kinetics of the extraction process from female inflorescences of Canapa sativa subsp. sativa var. sativa were studied, on the basis of determination of the content of cannabinoids: cannabidiolic acid (CBDA), Δ9-tetrahydrocannabinolic acid (THCA), cannabidiol (CBD) and Δ9-tetrahydrocannabinol (THC), before and after decarboxylation in the oven, in order to evaluate the possible use of the hemp extract obtained in the food sector. Therefore, both conventional maceration (CM) and rapid solid-liquid dynamic extraction (RSLDE), also known as cyclically pressurized extraction (CPE), were carried out, using parts of the plant approximately of the same size. The alcoholic extracts thus obtained were analyzed by high-performance liquid chromatography (HPLC) in order to calculate the percentages of cannabinoids present in the inflorescences and thus be able to evaluate the degree of decarboxylation. Furthermore, the extracts were dried to calculate the percentage of solid material present in it, that was made mainly by cannabinoids. The amount of substance extracted from the inflorescences was about 10% (w/w), for both cases considered. Therefore, the extraction yield was the same in the two cases examined and the final qualities were almost identical. However, the extraction times were significantly different. In fact, the maceration of hemp inflorescences in ethyl alcohol was completed in no less than 24 h, while with the RSLDE the extraction was completed in only 4 h. Finally, for a better understanding of the extraction process with cyclically pressurized extraction, a numerical simulation was carried out which allowed to better evaluate the influence of extractive parameters. Full article
(This article belongs to the Special Issue Extraction and Isolation of Natural Products)
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