Separations

15 pages, 3373 KiB

Open AccessEditor’s ChoiceArticle

Characterization and Photocatalytic Performance of Newly Synthesized ZnO Nanoparticles for Environmental Organic Pollutants Removal from Water System

by Vesna Despotović, Nina Finčur, Sabolč Bognar, Daniela Šojić Merkulov, Predrag Putnik, Biljana Abramović and Sanja Panić

Separations 2023, 10(4), 258; https://doi.org/10.3390/separations10040258 - 16 Apr 2023

Cited by 6 | Viewed by 2042

Abstract

Most countries are facing problems of environmental pollution due to toxic organic pollutants being discharged into the environment from various man-made sources. Heterogeneous photocatalysis is a possible solution for the mentioned problem, and it has been widely applied for the removal of pollutants [...] Read more.

Most countries are facing problems of environmental pollution due to toxic organic pollutants being discharged into the environment from various man-made sources. Heterogeneous photocatalysis is a possible solution for the mentioned problem, and it has been widely applied for the removal of pollutants from aqueous solutions, thanks to its high removal efficiency and environmental friendliness. Among the commonly used metal oxides, ZnO has attracted researchers’ interests due to its ecofriendly and nontoxic nature. In this work, ZnO nanoparticles (ZnO-NPs) were prepared by the precipitation method from water (w) and ethanol solutions of the corresponding metal precursors (zinc–acetate dihydrate, A_ZnO, and zinc–nitrate hexahydrate, N_ZnO) followed by calcination at different temperatures. The structure and morphology of the prepared catalysts were characterized by different techniques (XRD, BET, and SEM). Based on the XRD results, it can be seen that the synthesized NPs possess high purity. Furthermore, at a higher calcination temperature, a higher crystal size was observed, which was more intense in the case of the ethanol solution of the precursors. The BET analysis showed macropores at the surface and also indicated that the increased temperature led to decreased surface area. Finally, SEM images showed that in the case of the water precursor solution, an irregular, rod-like shape of the NPs was observed. The photocatalytic properties of newly synthesized ZnO-NPs exposed to simulated sunlight were examined during the removal of pesticide clomazone (CLO) and the antidepressant drug amitriptyline (AMI). ZnO-NPs prepared by the precipitation method from the water solution of zinc–acetate dihydrate and calcined at 500 °C (A_ZnOw_500) showed the highest performance under simulated sunlight. Furthermore, the activity of A_ZnOw_500 and N_ZnOw_500 catalysts in the removal of three organic pollutants from water—two pesticides (sulcotrione (SUL) and CLO) and one pharmaceutical (AMI)—was also compared. Results showed that decreased photocatalytic activity was observed in the presence of N_ZnOw_500 NPs in all investigated systems. Finally, the effect of the initial pH was also examined. It was found that in the case of CLO and SUL, there was no influence of the initial pH, while in the case of AMI the k_app was slightly increased in the range from pH ~7 to pH ~10. Full article

(This article belongs to the Section Environmental Separations)

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23 pages, 6194 KiB

Open AccessEditor’s ChoiceArticle

Multidimensional Fractionation of Particles

by Uwe Frank, Jana Dienstbier, Florentin Tischer, Simon E. Wawra, Lukas Gromotka, Johannes Walter, Frauke Liers and Wolfgang Peukert

Separations 2023, 10(4), 252; https://doi.org/10.3390/separations10040252 - 13 Apr 2023

Cited by 3 | Viewed by 2019

Abstract

The increasing complexity in particle science and technology requires the ability to deal with multidimensional property distributions. We present the theoretical background for multidimensional fractionations by transferring the concepts known from one dimensional to higher dimensional separations. Particles in fluids are separated by [...] Read more.

The increasing complexity in particle science and technology requires the ability to deal with multidimensional property distributions. We present the theoretical background for multidimensional fractionations by transferring the concepts known from one dimensional to higher dimensional separations. Particles in fluids are separated by acting forces or velocities, which are commonly induces by external fields, e.g., gravitational, centrifugal or electro-magnetic fields. In addition, short-range force fields induced by particle interactions can be employed for fractionation. In this special case, nanoparticle chromatography is a recent example. The framework for handling and characterizing multidimensional separation processes acting on multidimensional particle size distributions is presented. Illustrative examples for technical realizations are given for shape-selective separation in a hydrocyclone and for density-selective separation in a disc separator. Full article

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17 pages, 1944 KiB

Open AccessEditor’s ChoiceArticle

Salting-Out Assisted Liquid-Liquid Extraction for UPLC-MS/MS Determination of Thyroxine and Steroid Hormones in Human Serum and Fish Plasma

by Alemnesh Yirda Urge, Daniela Maria Pampanin, Maria Elena Martino, David Lausten Knudsen and Cato Brede

Separations 2023, 10(4), 240; https://doi.org/10.3390/separations10040240 - 5 Apr 2023

Cited by 2 | Viewed by 3966

Abstract

Measuring the level of steroid and thyroxine hormones is key to understanding organism health conditions. Liquid chromatography coupled with tandem mass spectrometry has become the method of choice for such hormone analyses in clinical laboratories. Detection of hormones at low levels typically requires [...] Read more.

Measuring the level of steroid and thyroxine hormones is key to understanding organism health conditions. Liquid chromatography coupled with tandem mass spectrometry has become the method of choice for such hormone analyses in clinical laboratories. Detection of hormones at low levels typically requires a time-consuming sample preparation, such as liquid-liquid extraction followed by solvent evaporation and re-solubilization of the sample extract. Instead, we applied salting-out assisted liquid-liquid extraction (SALLE) for the extraction of thyroxine, testosterone, cortisone, and cortisol from human serum and fish plasma samples. SALLE allowed direct injection of sample extracts. Sodium chloride and ammonium sulfate were evaluated as salting-out reagents together with four different organic solvents. High extraction recovery and reduced matrix interference were achieved by using ammonium sulfate together with 10% methanol in acetonitrile. Limits of quantification were in the range of 0.1–0.2 ng/mL and signal responses were linear (R2 > 0.997) up to at least 100 ng/mL for all hormones. The method was applied for hormone measurements in fish plasma. In conclusion, SALLE combines the simplicity of crude protein precipitation with the high analyte enrichment of a liquid-liquid extraction. Here we have presented it as a novel sample preparation method for clinical laboratories where mass spectrometry is utilized in the field of endocrinology. Full article

(This article belongs to the Special Issue Mass Spectrometry Development and Its Application in Bioanalysis)

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18 pages, 5932 KiB

Open AccessEditor’s ChoiceArticle

Green-Engineered Barrier Creams with Montmorillonite-Chlorophyll Clays as Adsorbents for Benzene, Toluene, and Xylene

by Meichen Wang and Timothy D. Phillips

Separations 2023, 10(4), 237; https://doi.org/10.3390/separations10040237 - 4 Apr 2023

Cited by 9 | Viewed by 4902

Abstract

Dermal exposures to hazardous environmental chemicals in water can significantly affect the morphology and integrity of skin structure, leading to enhanced and deeper penetration. Organic solvents, such as benzene, toluene, and xylene (BTX), have been detected in humans following skin exposure. In this [...] Read more.

Dermal exposures to hazardous environmental chemicals in water can significantly affect the morphology and integrity of skin structure, leading to enhanced and deeper penetration. Organic solvents, such as benzene, toluene, and xylene (BTX), have been detected in humans following skin exposure. In this study, novel barrier cream formulations (EVB^TM) engineered with either montmorillonite (CM and SM) or chlorophyll-amended montmorillonite (CMCH and SMCH) clays were tested for their binding efficacy for BTX mixtures in water. The physicochemical properties of all sorbents and barrier creams were characterized and were shown to be suitable for topical application. In vitro adsorption results indicated that EVB-SMCH was the most effective and favorable barrier for BTX, as supported by the high binding percentage (29–59% at 0.05 g and 0.1 g), stable binding at equilibrium, low desorption rates, and high binding affinity. Pseudo-second-order and the Freundlich models best fit the adsorption kinetics and isotherms, and the adsorption was an exothermic reaction. Ecotoxicological models using L. minor and H. vulgaris that were submersed in aqueous culture media showed that the inclusion of 0.05% and 0.2% EVB-SMCH reduced BTX concentration. This result was further supported by the significant and dose-dependent increase in multiple growth endpoints, including plant frond number, surface area, chlorophyll content, growth rate, inhibition rate, and hydra morphology. The in vitro adsorption results and in vivo plant and animal models indicated that green-engineered EVB-SMCH can be used as an effective barrier to bind BTX mixtures and interrupt their diffusion and dermal contact. Full article

(This article belongs to the Special Issue Applications of Porous Materials in Adsorption)

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24 pages, 6367 KiB

Open AccessEditor’s ChoiceReview

Removal of Azo Dyes from Wastewater through Heterogeneous Photocatalysis and Supercritical Water Oxidation

by Vincenzo Vaiano and Iolanda De Marco

Separations 2023, 10(4), 230; https://doi.org/10.3390/separations10040230 - 27 Mar 2023

Cited by 37 | Viewed by 7175

Abstract

Azo dyes are synthetic organic dyes used in the textile, leather, and paper industries. They pose environmental problems due to their toxic and persistent nature. The toxicity is due to the presence of azo groups in the dye molecule that can break down [...] Read more.

Azo dyes are synthetic organic dyes used in the textile, leather, and paper industries. They pose environmental problems due to their toxic and persistent nature. The toxicity is due to the presence of azo groups in the dye molecule that can break down into aromatic amines, which are highly toxic to aquatic organisms and humans. Various treatment methods have been developed to remove azo dyes from wastewater. Conventional wastewater treatments have some drawbacks, such as high operating costs, long processing times, generation of sludge, and the formation of toxic by-products. For these reasons, a valid alternative is constituted by advanced oxidation processes. Good results have been obtained using heterogeneous photocatalysis and supercritical water oxidation. In the former method, a photocatalyst is in contact with wastewater, a suitable light activates the catalyst, and generated reactive oxygen species that react with pollutants through oxidative reactions to their complete mineralization; the latter involves pressurizing and heating wastewater to supercritical conditions in a reactor vessel, adding an oxidizing agent to the supercritical water, and allowing the mixture to react. In this review paper, works in the literature that deal with processing wastewater containing azo dyes through photocatalysts immobilized on macroscopic supports (structured photocatalysts) and the supercritical water oxidation technique have been critically analyzed. In particular, advancement in the formulation of structured photocatalysts for the degradation of azo dyes has been shown, underlying different important features, such as the type of support for the photoactive phase, reactor configuration, and photocatalytic efficiency in terms of dye degradation and photocatalyst stability. In the case of supercritical water oxidation, the main results regarding COD and TOC removal from wastewater containing azo dyes have been reported, taking into account the reactor type, operating pressure, and temperature, as well as the reaction time. Full article

(This article belongs to the Special Issue Development of Materials for Separation and Detection of Metals and Chemicals)

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15 pages, 1865 KiB

Open AccessEditor’s ChoiceArticle

Development and Validation of a Confirmatory Method for the Determination of 12 Coccidiostat Residues in Eggs and Muscle by Means of Liquid Chromatography Coupled to Hybrid High Resolution Mass Spectrometry

by Federica Castellani, Matteo Ricci, Maria Novella Colagrande, Giampiero Scortichini and Giorgio Saluti

Separations 2023, 10(3), 202; https://doi.org/10.3390/separations10030202 - 14 Mar 2023

Cited by 5 | Viewed by 2432

Abstract

A confirmatory, highly selective multi-residue method based on liquid chromatography coupled to hybrid high resolution mass spectrometry (LC-Q-Orbitrap) was developed and validated for the determination of 12 regulated coccidiostats in eggs and muscle. Particularly, ionophore antibiotics (lasalocid, maduramicin, monensin, narasin, salinomycin and semduramicin) [...] Read more.

A confirmatory, highly selective multi-residue method based on liquid chromatography coupled to hybrid high resolution mass spectrometry (LC-Q-Orbitrap) was developed and validated for the determination of 12 regulated coccidiostats in eggs and muscle. Particularly, ionophore antibiotics (lasalocid, maduramicin, monensin, narasin, salinomycin and semduramicin) and synthetic coccidiostats (diclazuril, halofuginone, nicarbazin as 4,4′-dinitrocarbanilide fraction, robenidine and toltrazuril as toltrazuril-sulphone) were included in the method. The sample preparation consisted in the extraction of the analytes from the matrix with acetonitrile, followed by a clean-up step with Oasis^® PRiME HLB SPE and a defatting procedure with n-hexane. Validation was successfully performed according to Commission Implementing Regulation (EU) 2021/808, starting from 1 µg kg⁻¹. The procedure was verified through the analysis of a certified reference material (CRM) and the occurrence of the residues was assessed in the context of the Italian National Residue Control Plan (NRCP). Full article

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

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32 pages, 3193 KiB

Open AccessEditor’s ChoiceReview

Application of Hydrogen-Bonded Organic Frameworks in Environmental Remediation: Recent Advances and Future Trends

by Yu Zhang, Mengfei Tian, Zahid Majeed, Yuxin Xie, Kaili Zheng, Zidan Luo, Chunying Li and Chunjian Zhao

Separations 2023, 10(3), 196; https://doi.org/10.3390/separations10030196 - 13 Mar 2023

Cited by 12 | Viewed by 4610

Abstract

The hydrogen-bonded organic frameworks (HOFs) are a class of porous materials with crystalline frame structures, which are self-assembled from organic structures by hydrogen bonding in non-covalent bonds π-π packing and van der Waals force interaction. HOFs are widely used in environmental remediation due [...] Read more.

The hydrogen-bonded organic frameworks (HOFs) are a class of porous materials with crystalline frame structures, which are self-assembled from organic structures by hydrogen bonding in non-covalent bonds π-π packing and van der Waals force interaction. HOFs are widely used in environmental remediation due to their high specific surface area, ordered pore structure, pore modifiability, and post-synthesis adjustability of various physical and chemical forms. This work summarizes some rules for constructing stable HOFs and the synthesis of HOF-based materials (synthesis of HOFs, metallized HOFs, and HOF-derived materials). In addition, the applications of HOF-based materials in the field of environmental remediation are introduced, including adsorption and separation (NH₃, CO₂/CH₄ and CO₂/N₂, C₂H₂/C₂H_e and C_eH₆, C₂H₂/CO₂, Xe/Kr, etc.), heavy metal and radioactive metal adsorption, organic dye and pesticide adsorption, energy conversion (producing H₂ and CO₂ reduced to CO), organic dye degradation and pollutant sensing (metal ion, aniline, antibiotic, explosive steam, etc.). Finally, the current challenges and further studies of HOFs (such as functional modification, molecular simulation, application extension as remediation of contaminated soil, and cost assessment) are discussed. It is hoped that this work will help develop widespread applications for HOFs in removing a variety of pollutants from the environment. Full article

(This article belongs to the Special Issue Applications of Porous Materials in Adsorption)

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18 pages, 4876 KiB

Open AccessEditor’s ChoiceArticle

Deep Eutectic Solvent-Based Microwave-Assisted Extraction for the Extraction of Seven Main Flavonoids from Ribes mandshuricum (Maxim.) Kom. Leaves

by Wei Wang, Si-Qiu Xiao, Ling-Yu Li and Qing-Yan Gai

Separations 2023, 10(3), 191; https://doi.org/10.3390/separations10030191 - 10 Mar 2023

Cited by 7 | Viewed by 2965

Abstract

Flavonoids exhibit many biological properties, so it is very important to find an efficient and green method to extract them from plant materials. In this paper, DES-MAE (deep eutectic solvent-based microwave-assisted extraction) technique was developed to extract the seven major active flavonoids from [...] Read more.

Flavonoids exhibit many biological properties, so it is very important to find an efficient and green method to extract them from plant materials. In this paper, DES-MAE (deep eutectic solvent-based microwave-assisted extraction) technique was developed to extract the seven major active flavonoids from Ribes mandshuricum leaves, namely, trifolin, isoquercetin, rutin, astragalin, quercetin, hyperoside, and kaempferol. After the completion of the extraction process, macroporous adsorption resin was used for the purification of seven flavonoids. The BBD (Box–Behnken design) method combined with RSM (response surface methodology) was applied to acquire the optimal operating conditions of DES-MAE. The optimal parameters were: temperature: 54 °C, time: 10 min, extraction solvent: choline chloride/lactic acid with a 1:2 mass ratio, water content: 25%, and liquid/solid ratio: 27 mL/g. The yields of the seven target flavonoids were 4.78, 2.57, 1.25, 1.15, 0.34, 0.32, and 0.093 mg/g DW (dry weight), respectively. The direct purification of trifolin, isoquercetin, rutin, astragalin, quercetin, hyperoside, and kaempferol in DES-MAE solution was achieved by using macroporous resin X-5. The recoveries were 87.02%, 81.37%, 79.64%, 87.13%, 97.36%, 88.08%, and 99.39%, respectively. The results showed that DES-MAE followed by MRCC (macroporous resin column chromatography) represents a promising approach to extracting and separating active components from plants. Full article

(This article belongs to the Special Issue Novel Approach for Natural Product Separation from Plants)

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15 pages, 7415 KiB

Open AccessEditor’s ChoiceReview

Steric Exclusion Chromatography for Purification of Biomolecules—A Review

by Jennifer J. Labisch, G. Philip Wiese and Karl Pflanz

Separations 2023, 10(3), 183; https://doi.org/10.3390/separations10030183 - 8 Mar 2023

Cited by 2 | Viewed by 3720

Abstract

Steric exclusion chromatography (SXC) is a purification method that is based on steric exclusion effects from the surface of the target and a hydrophilic stationary phase after the addition of polyethylene glycol (PEG), which leads to an association of the target with the [...] Read more.

Steric exclusion chromatography (SXC) is a purification method that is based on steric exclusion effects from the surface of the target and a hydrophilic stationary phase after the addition of polyethylene glycol (PEG), which leads to an association of the target with the stationary phase without direct binding, such as covalent, electrostatic, and hydrophilic/hydrophobic interactions. The gentle nature of the method has led to an increased focus on sensitive targets such as enveloped viruses with potential for other sensitive entities, e.g., extracellular vesicles and virus-like particles. SXC is related to PEG-mediated protein precipitation, but investigation of further process parameters was crucial to gain a better understanding of the SXC method. After explaining mechanistic fundamentals and their discovery, this review summarizes the findings on SXC from its first reference 11 years ago until today. Different applications of SXC are presented, demonstrating that the method can be used for a wide variety of targets and achieves high recovery rates and impurity removal. Further, critical process parameters for successful process implementation are discussed, including technical requirements, buffer composition, and scalability. Full article

(This article belongs to the Special Issue Advances in Separation Engineering)

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17 pages, 2273 KiB

Open AccessEditor’s ChoiceArticle

Characterization of the Aroma Profile of Food Smoke at Controllable Pyrolysis Temperatures

by Marina Rigling, Laura Höckmeier, Malte Leible, Kurt Herrmann, Monika Gibis, Jochen Weiss and Yanyan Zhang

Separations 2023, 10(3), 176; https://doi.org/10.3390/separations10030176 - 6 Mar 2023

Cited by 9 | Viewed by 2723

Abstract

Smoking is used to give food its typical aroma and to obtain the desired techno-functional properties of the product. To gain a deeper knowledge of the whole process of food smoking, a controllable smoking process was developed, and the influence of wood pyrolysis [...] Read more.

Smoking is used to give food its typical aroma and to obtain the desired techno-functional properties of the product. To gain a deeper knowledge of the whole process of food smoking, a controllable smoking process was developed, and the influence of wood pyrolysis temperature (150–900 °C) on the volatile compounds in the smoking chamber atmosphere was investigated. The aroma profile of smoke was decoded by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). Subsequently, the correlations in the most important substance classes, as well as in individual target components, were investigated by the Pearson test. Phenols and lactones showed an increase over the entire applied temperature range (r_T = 0.94 and r_T = 0.90), whereas furans and carbonyls showed no strict temperature dependence (r_T < 0.6). Investigations on single aroma compounds showed that not all compounds of one substance class showed the same behavior, e.g., guaiacol showed no significant increase over the applied pyrolysis temperature, whereas syringol and hydoxyacetone showed a plateau after 450 °C, and phenol and cyclotene increased linear over the applied temperature range. These findings will help to better understand the production of aroma-active compounds during smoke generation in order to meet consumers preferences. Full article

(This article belongs to the Special Issue Application of Chromatography in Analytical Chemistry)

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17 pages, 2117 KiB

Open AccessEditor’s ChoiceArticle

Experimental Design and Multiple Response Optimization for the Extraction and Quantitation of Thirty-Four Priority Organic Micropollutants in Tomatoes through the QuEChERS Approach

by Luca Rivoira, Massimo Del Bubba, Giasmin Cecconi, Michele Castiglioni, Valentina Testa, Mattia Isola and Maria Concetta Bruzzoniti

Separations 2023, 10(3), 174; https://doi.org/10.3390/separations10030174 - 6 Mar 2023

Cited by 2 | Viewed by 2204

Abstract

The chemical contamination in fruit and vegetables represents a challenging analytical issue, with tomatoes deserving to be investigated as they are fundamental components of the Mediterranean diet. Polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs contamination is of serious concern, due to [...] Read more.

The chemical contamination in fruit and vegetables represents a challenging analytical issue, with tomatoes deserving to be investigated as they are fundamental components of the Mediterranean diet. Polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs contamination is of serious concern, due to particulate deposition and to uptake from contaminated soils and water. However, time-consuming, non-simultaneous and/or non-eco-friendly extraction procedures are typically used to investigate organic contamination in tomatoes, with nitro-PAHs that have not yet been studied. Based on these premises, this work reports the development of a QuEChERS-based approach, coupled with gas chromatography/mass spectrometry, for the simultaneous determination of 16 PAHs, 14 PCBs and 4 nitro-PAHs in three tomato cultivars. The effect of dichloromethane, cyclohexane and acetone, as well as of four clean-up phases were studied through the advanced combination of full factorial experimental design and multiple response optimization approaches. The final protocol, based on cyclohexane extraction followed by a double purification step with primary secondary amine and octadecyl silica and a sulfuric acid oxidation, led to 60–120% recoveries (RSD% < 15%). Good repeatability (inter-day precision <15%) and negligible matrix effect (<16%) were confirmed and the protocol was applied to the analysis of real tomato samples purchased in a local market. Full article

(This article belongs to the Section Environmental Separations)

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15 pages, 2820 KiB

Open AccessEditor’s ChoiceArticle

Effect of Surfactants on Reverse Osmosis Membrane Performance

by Aymen Halleb, Mitsutoshi Nakajima, Fumio Yokoyama and Marcos Antonio Neves

Separations 2023, 10(3), 168; https://doi.org/10.3390/separations10030168 - 2 Mar 2023

Cited by 6 | Viewed by 3504

Abstract

The aim of this study was to evaluate the performance of a reverse osmosis (RO) membrane in surfactant removal using various surfactant model aqueous solutions. The separation tests were performed with laboratory scale units in a dead-end configuration. Cellulose Acetate (CA) and Polyamide [...] Read more.

The aim of this study was to evaluate the performance of a reverse osmosis (RO) membrane in surfactant removal using various surfactant model aqueous solutions. The separation tests were performed with laboratory scale units in a dead-end configuration. Cellulose Acetate (CA) and Polyamide (PA) RO membranes were used with nonionic, anionic, or cationic surfactants at a wide range of concentrations. Membrane performance was evaluated using permeate flux and total organic carbon (TOC) rejection. The effects of surfactant type and concentration on RO membranes were assessed. Permeate flux of the PA membrane depended on the surfactant type and concentration. The separation of cationic surfactant aqueous solutions yielded the lowest permeate flux, followed by nonionic and anionic surfactant aqueous solutions, respectively. Surfactant adsorption on the membrane surface occurred at very low concentration of cationic and nonionic surfactants due to electrostatic and hydrophobic interactions, respectively, which affected permeate flux, and micelles did not affect the permeate flux of PA membrane. However, for CA membrane the permeate flux was not affected by the feed solution. Both membranes exhibited satisfactory TOC rejection (92–99%). This study highlights the importance of assessing interactions between membrane material and surfactant molecules to mitigate membrane fouling and guarantee a better performance of the RO membrane. Full article

(This article belongs to the Special Issue Separation Technologies in Water and Wastewater Treatment and Resources Recovery)

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19 pages, 4976 KiB

Open AccessEditor’s ChoiceArticle

Determination of 27 Glucocorticoids in Urine by Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry Using UniSpray^TM Source

by Mariola Wicka, Krzysztof Grucza, Aleksandra Drapała, Patryk Konarski and Dorota Kwiatkowska

Separations 2023, 10(3), 155; https://doi.org/10.3390/separations10030155 - 24 Feb 2023

Cited by 1 | Viewed by 2170

Abstract

Glucocorticoids (GCs) are a group of the most important and commonly used anti-inflammatory, antiallergenic, and immunosuppressive drugs. Like narcotics, they can be addictive if taken at increasing doses to achieve greater analgesic effects. The purpose of the study was to develop initial and [...] Read more.

Glucocorticoids (GCs) are a group of the most important and commonly used anti-inflammatory, antiallergenic, and immunosuppressive drugs. Like narcotics, they can be addictive if taken at increasing doses to achieve greater analgesic effects. The purpose of the study was to develop initial and confirmation testing analytical methods that would allow for the identification of glucocorticoid class substances in human urine to be used for routine analyses for the purposes of prosecution in the case of abuse, for clinical toxicology, medical jurisprudence, as well as for routine testing of athletes for the presence of prohibited substances in sports by means of ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) using a new generation ionization source UniSprayTM (U.S). This new method allows for the simultaneous detection of 27 glucocorticoids in human urine using LC-MS/MS. The tests conducted yielded relatively low LOD and LOQ values, ranging from 0.06 ng/mL to 0.14 ng/mL and 0.75 ng/mL for LOD and LOQ, respectively. Full article

(This article belongs to the Topic Application of Analytical Chemistry in Exercise Physiology and Pharmacology)

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16 pages, 821 KiB

Open AccessEditor’s ChoiceReview

Solid Phase Microextraction—A Promising Tool for Graft Quality Monitoring in Solid Organ Transplantation

by Kamil Łuczykowski, Natalia Warmuzińska and Barbara Bojko

Separations 2023, 10(3), 153; https://doi.org/10.3390/separations10030153 - 23 Feb 2023

Cited by 2 | Viewed by 1626

Abstract

Solid organ transplantation is a life-saving intervention for patients suffering from end-stage organ failure. Although improvements in surgical techniques, standards of care, and immunosuppression have been observed over the last few decades, transplant centers have to face the problem of an insufficient number [...] Read more.

Solid organ transplantation is a life-saving intervention for patients suffering from end-stage organ failure. Although improvements in surgical techniques, standards of care, and immunosuppression have been observed over the last few decades, transplant centers have to face the problem of an insufficient number of organs for transplantation concerning the growing demand. An opportunity to increase the pool of organs intended for transplantation is the more frequent use of organs from extended criteria and the development of analytical methods allowing for a better assessment of the quality of organs to minimize the risk of post-transplant organ injury and rejection. Therefore, solid-phase microextraction (SPME) has been proposed in various studies as an effective tool for determining compounds of significance during graft function assessment or for the chemical profiling of grafts undergoing various preservation protocols. This review summarizes how SPME addresses the analytical challenges associated with different matrices utilized in the peri-transplant period and discusses its potential as a diagnostic tool in future work. Full article

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

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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 10 | Viewed by 3603

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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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 5 | Viewed by 2809

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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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 5879

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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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 4013

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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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 3 | Viewed by 1843

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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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 1558

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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45 pages, 3584 KiB

Open AccessEditor’s ChoiceReview

The State of Critical and Strategic Metals Recovery and the Role of Nuclear Techniques in the Separation Technologies Development: Review

by Nelson R. Kiprono, Tomasz Smolinski, Marcin Rogowski and Andrzej G. Chmielewski

Separations 2023, 10(2), 112; https://doi.org/10.3390/separations10020112 - 5 Feb 2023

Cited by 7 | Viewed by 3569

Abstract

The extraction of useful minerals or geological materials from the Earth’s crust, most typically from various sources, is crucial to a country’s development and progress. Mineral-rich countries use these resources to transform their economies and propel them toward long-term prosperity. There is an [...] Read more.

The extraction of useful minerals or geological materials from the Earth’s crust, most typically from various sources, is crucial to a country’s development and progress. Mineral-rich countries use these resources to transform their economies and propel them toward long-term prosperity. There is an urgent need for the world to increase mineral exploration efforts, improve the recycling of important metal-containing resources, and extract them using upgraded hydrometallurgical procedures with high recovery efficiency. This review paper highlights the importance of strategic and critical metals in the economy and the role of nuclear techniques in the analysis, process optimization, and remediation of metals using solvent extraction, adsorption, and chromatographic resins. Radiotracer analysis, X-Ray Fluorescence spectrometry (XRF), Neutron Activation Analysis (NAA), and X-Ray Diffraction (XRD) are appropriate for improving laboratory-based hydrometallurgical processes, with future technical and economic benefits. The development and installation of novel instruments to provide the real-time control of mining and mineral processing plants for improved control have the potential to aid in the recovery of a broad range of metals. Full article

(This article belongs to the Special Issue Recent Advances in Metal Separations and Recovery)

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28 pages, 2055 KiB

Open AccessEditor’s ChoiceReview

Identification and Isolation Techniques for Plant Growth Inhibitors in Rice

by Nguyen Thi Hai Anh, La Hoang Anh, Nguyen Phuong Mai, Nguyen Van Quan and Tran Dang Xuan

Separations 2023, 10(2), 105; https://doi.org/10.3390/separations10020105 - 3 Feb 2023

Cited by 2 | Viewed by 3923

Abstract

Plant growth inhibitors (PGIs) in rice (Oryza sativa), or rice allelochemicals, are secondary metabolites that are either exudated by rice plants to cope with natural competitors or produced during the decomposition of rice by-products in the paddy fields. Of these, the [...] Read more.

Plant growth inhibitors (PGIs) in rice (Oryza sativa), or rice allelochemicals, are secondary metabolites that are either exudated by rice plants to cope with natural competitors or produced during the decomposition of rice by-products in the paddy fields. Of these, the major groups of rice PGIs include phenolics, flavonoids, terpenoids, alkaloids, steroids, and fatty acids, which also exhibit potential medicinal and pharmaceutical properties. Recently, the exploitation of rice PGIs has attracted considerable attention from scientists worldwide. The biosynthesis, exudation, and release of PGIs are dependent on environmental conditions, relevant gene expression, and biodiversity among rice varieties. Along with the mechanism clarification, numerous analytical methods have been improved to effectively support the identification and isolation of rice PGIs during the last few decades. This paper provides an overview of rice PGIs and techniques used for determining and extracting those compounds from rice. In particular, the features, advantages, and limitations of conventional and upgraded extraction methods are comprehensively reported and discussed. The conventional extraction methods have been gradually replaced by advanced techniques consisting of pressurized liquid extraction (PLE), microwave-assisted extraction (MAE), and solid-phase extraction (SPE). Meanwhile, thin-layer chromatography (TLC), liquid chromatography (LC), gas chromatography (GC), mass spectrometry (MS), nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HR-MS), infrared spectroscopy (IR), near-infrared spectroscopy (NIRS), and X-ray crystallography are major tools for rice PGI identification and confirmation. With smart agriculture becoming more prevalent, the statistics of rice PGIs and extraction methods will help to provide useful datasets for building an autonomous model for safer weed control. Conceivably, the efficient exploitation of rice PGIs will not only help to increase the yield and economic value of rice but may also pave the way for research directions on the development of smart and sustainable rice farming methods. Full article

(This article belongs to the Special Issue Separation, Extraction and Purification of Natural Products)

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19 pages, 3792 KiB

Open AccessEditor’s ChoiceArticle

Screening the Efficacy of a Microbial Consortium of Bacteria and Fungi Isolated from Different Environmental Samples for the Degradation of LDPE/TPS Films

by Dajana Kučić Grgić, Martina Miloloža, Vesna Ocelić Bulatović, Šime Ukić, Miroslav Slouf and Veronika Gajdosova

Separations 2023, 10(2), 79; https://doi.org/10.3390/separations10020079 - 24 Jan 2023

Cited by 7 | Viewed by 3962

Abstract

In this study, a screening of the efficacy of a microbial consortium of bacteria and fungi isolated from activated sludge, river sediment, and compost for the degradation of LDPE/TPS was performed. According to the morphological and biochemical characterization, eight bacteria, Bacillus sonorensis, [...] Read more.

In this study, a screening of the efficacy of a microbial consortium of bacteria and fungi isolated from activated sludge, river sediment, and compost for the degradation of LDPE/TPS was performed. According to the morphological and biochemical characterization, eight bacteria, Bacillus sonorensis, Bacillus subtilis, Lysinibacillus massiliensis, Bacillus licheniformis, Bacillus indicus, Bacillus megaterium, Bacillus cereus, and Pseudomonas alcaligenes, five molds, Aspergillus sp. 1, Aspergillus sp. 2, Trichoderma sp., Rhizopus sp., Penicillium sp., and Alternaria sp., and a yeast, Candida parapsilosis, were identified. The first experiment E1 was inoculated with microorganisms isolated from activated sludge and river sediment, and E2 with microorganisms isolated from compost. In both experiments, different types of polymeric materials, low density polyethylene (E1-1 and E2-1), thermoplastic starch (E1-2 and E2-2), low density polyethylene + thermoplastic starch (E1-3 and E2-3), low density polyethylene + thermoplastic starch + styrene-ethylene-styrene (E1-4 and E2-4) were added. The obtained results, weight loss, SEM, and FTIR analysis showed that the microorganisms in both experiments were able to degrade polymeric materials. The mixed culture of microorganisms in experiments E1-2 and E2-2 completely degraded TPS (thermoplastic starch). The percent weight losses of LDPE, LDPE+20% TPS, and LDPE+20% TPS+SEBS in experiment E1 were 3.3184%, 14.1152%, and 16.0062% and in experiment E2 were 3.9625%, 20.4520% and 21.9277%, respectively. SEM microscopy shows that the samples with a LDPE matrix exhibited moderate surface degradation and negligible oxidative degradation under the given conditions. FTIR/ATR data demonstrate that degradation was more intense in E2 than in E1. Full article

(This article belongs to the Section Environmental Separations)

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37 pages, 1502 KiB

Open AccessEditor’s ChoiceReview

Factors Influencing the Prediction Accuracy of Model Peptides in Reversed-Phase Liquid Chromatography

by Othman Al Musaimi, Oscar M. Mercado-Valenzo and Daryl R. Williams

Separations 2023, 10(2), 81; https://doi.org/10.3390/separations10020081 - 24 Jan 2023

Cited by 3 | Viewed by 2613

Abstract

Hydrophobicity is an important physicochemical property of peptides in solution. As well as being strongly associated with peptide stability and aggregation, hydrophobicity governs the solution based chromatographic separation processes, specifically reversed-phase liquid chromatography (RPLC). In addition, hydrophobicity is a major physicochemical property of [...] Read more.

Hydrophobicity is an important physicochemical property of peptides in solution. As well as being strongly associated with peptide stability and aggregation, hydrophobicity governs the solution based chromatographic separation processes, specifically reversed-phase liquid chromatography (RPLC). In addition, hydrophobicity is a major physicochemical property of peptides in comparison to H-bonding, electrostatic, and aromatic properties in intermolecular interactions. However, a wide range of molecular factors can influence peptide hydrophobicity, with accurate predictions depending on specific peptide amino acid compositions, structure, and conformation. It is noticeable that peptide composition, the position of the amino acid, and its neighbouring groups play a crucial role in the elution process. In light of this, the same amino acid behaved differently depending on its position and neighbouring amino acid in the peptide chain. Extra attention should be paid to the denaturation process during the course of elution, as it has been shown to complicate and alter the elution pattern. This paper reports on the key peptide properties that can alter hydrophobicity and, consequently, the RPLC elution behaviour of the peptides, and it will conclude by proposing improved prediction algorithms for peptide elution in RPLC. Full article

(This article belongs to the Special Issue Advances in Chromatographic Analysis of Bioactive Compounds)

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16 pages, 4682 KiB

Open AccessEditor’s ChoiceArticle

Dimethyl Carbonate as a Mobile-Phase Modifier for Normal-Phase and Hydrophilic Interaction Liquid Chromatography

by Philip D. Boes, Sophie R. Elleman and Neil D. Danielson

Separations 2023, 10(2), 70; https://doi.org/10.3390/separations10020070 - 18 Jan 2023

Cited by 8 | Viewed by 3973

Abstract

We studied the use of dimethyl carbonate (DMC) as a non-toxic, aprotic modifier for hydrophilic liquid interaction chromatography (HILIC) and as a modifier for normal-phase liquid chromatography (LC). A comparison of ethyl acetate (EA) and DMC as organic mobile-phase modifiers in hexane for [...] Read more.

We studied the use of dimethyl carbonate (DMC) as a non-toxic, aprotic modifier for hydrophilic liquid interaction chromatography (HILIC) and as a modifier for normal-phase liquid chromatography (LC). A comparison of ethyl acetate (EA) and DMC as organic mobile-phase modifiers in hexane for normal-phase LC of phthalates was conducted with a silica column and showed that retention factors (k) at the same modifier percentage were about a factor of two greater for DMC. Detection at 215 nm, possible with DMC, allowed for the better detection of the phthalates by a factor of 10, compared with EA detection, best at a 254 nm wavelength. Using a core-shell silica column, HILIC separations of trans-ferulic acid, syringic acid, and vanillic acid were compared between acetonitrile (MeCN) and DMC as the organic portion of the mobile phase, from 80–95%. The analyte retention for DMC, when compared to MeCN, was about 1.5 times greater, with only a moderate increase in back pressure. Plate count and peak asymmetry were somewhat better for the DMC chromatograms, compared to those with MeCN. Seven mono- and di-hydroxybenzoic acid positional isomers could be resolved effectively with DMC. Sorbate and benzoate preservatives in commercial drinks were also determined. Full article

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

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15 pages, 1348 KiB

Open AccessEditor’s ChoiceArticle

Improved Method for the Detection of Highly Polar Pesticides and Their Main Metabolites in Foods of Animal Origin: Method Validation and Application to Monitoring Programme

by Emanuela Verdini, Veronica Maria Teresa Lattanzio, Biancamaria Ciasca, Laura Fioroni and Ivan Pecorelli

Separations 2023, 10(1), 44; https://doi.org/10.3390/separations10010044 - 10 Jan 2023

Cited by 4 | Viewed by 2814

Abstract

The application of polar pesticides in agricultural production has been of great interest due to their low costs and their high effectiveness. For this reason, the possibility of their transfer to foods of animal origin is of great concern for human health. The [...] Read more.

The application of polar pesticides in agricultural production has been of great interest due to their low costs and their high effectiveness. For this reason, the possibility of their transfer to foods of animal origin is of great concern for human health. The manuscript describes the implementation and validation of an analytical method to detect polar pesticides, at regulatory levels, in three foods of animal origin, including bovine fat, chicken eggs, and cow milk. The method was fully validated to detect glyphosate, glufosinate, and their respective metabolites in the above-mentioned foods obtaining fit-for-purpose sensitivity, recoveries (76–119%), repeatability (≤20%), within-laboratory reproducibility (≤20%), and experimental measurement uncertainty less than 50% as required by the SANTE/11312/2021 criteria. Given the satisfactory results, the applicability of the method to additional molecules belonging to the same category (AMPA, cyanuric acid, ethephon, fosetyl aluminum, HEPA, maleic hydrazide, and N-acetyl-glyphosate) was also evaluated in order to meet possible future requests. Finally, the implemented method was applied to analyse samples over the period of March 2021 to August 2022 from two Italian regions (Umbria and Marche) within the national monitoring programme. In agreement with previously available data, none of the samples analysed showed the presence of glyphosate and glufosinate at levels above the legal limit. Full article

(This article belongs to the Special Issue Determination and Bio-Implications of Organic Pollutants in Food and Environmental Samples Based on Hyphenated Techniques)

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19 pages, 6437 KiB

Open AccessEditor’s ChoiceArticle

The Effect of the Elemental Composition of Municipal Sewage Sludge on the Phosphorus Recycling during Pyrolysis, with a Focus on the Char Chemistry—Modeling and Experiments

by Naeimeh Vali, Aurélie Combres, Aida Hosseinian and Anita Pettersson

Separations 2023, 10(1), 31; https://doi.org/10.3390/separations10010031 - 4 Jan 2023

Cited by 6 | Viewed by 1767

Abstract

The present study investigates how the original sewage sludge characteristics influence the composition of sewage sludge-based chars for land applications. Sewage sludge from two different wastewater treatment plants in Sweden was pyrolyzed at 500, 700, and 900 °C, and the resulting chars were [...] Read more.

The present study investigates how the original sewage sludge characteristics influence the composition of sewage sludge-based chars for land applications. Sewage sludge from two different wastewater treatment plants in Sweden was pyrolyzed at 500, 700, and 900 °C, and the resulting chars were analyzed. Thermodynamic equilibrium calculations (TEC), together with chemical fractionation, were implemented to simulate the char after the pyrolysis process at different temperatures. The results showed that, in general, for both the municipal sewage sludge (MSS), phosphorus (P) was significantly retained in the char at various temperatures. However, no specific correlation could be found between the pyrolysis temperature and the amount of P remaining. With regard to the heavy metals removed from the char after the pyrolysis reaction, the concentrations of copper, chromium, lead, nickel, zinc, and cadmium were below the limits of the Swedish regulations for farmland application. Full article

(This article belongs to the Special Issue Application of Green Separation Technology in Wastewater Treatment)

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28 pages, 2983 KiB

Open AccessEditor’s ChoiceReview

Mass Spectrometric Methods for Non-Targeted Screening of Metabolites: A Future Perspective for the Identification of Unknown Compounds in Plant Extracts

by Michael Sasse and Matthias Rainer

Separations 2022, 9(12), 415; https://doi.org/10.3390/separations9120415 - 7 Dec 2022

Cited by 6 | Viewed by 4517

Abstract

Phyto products are widely used in natural products, such as medicines, cosmetics or as so-called “superfoods”. However, the exact metabolite composition of these products is still unknown, due to the time-consuming process of metabolite identification. Non-target screening by LC-HRMS/MS could be a technique [...] Read more.

Phyto products are widely used in natural products, such as medicines, cosmetics or as so-called “superfoods”. However, the exact metabolite composition of these products is still unknown, due to the time-consuming process of metabolite identification. Non-target screening by LC-HRMS/MS could be a technique to overcome these problems with its capacity to identify compounds based on their retention time, accurate mass and fragmentation pattern. In particular, the use of computational tools, such as deconvolution algorithms, retention time prediction, in silico fragmentation and sophisticated search algorithms, for comparison of spectra similarity with mass spectral databases facilitate researchers to conduct a more exhaustive profiling of metabolic contents. This review aims to provide an overview of various techniques and tools for non-target screening of phyto samples using LC-HRMS/MS. Full article

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

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37 pages, 1644 KiB

Open AccessEditor’s ChoiceReview

Heterogeneous Catalytic Ozonation: Solution pH and Initial Concentration of Pollutants as Two Important Factors for the Removal of Micropollutants from Water

by Savvina Psaltou, Manassis Mitrakas and Anastasios Zouboulis

Separations 2022, 9(12), 413; https://doi.org/10.3390/separations9120413 - 6 Dec 2022

Cited by 12 | Viewed by 1845

Abstract

There are several publications on heterogeneous catalytic ozonation; however, their conclusions and the comparisons between them are not always consistent due to the variety of applied experimental conditions and the different solid materials used as catalysts. This review attempts to limit the major [...] Read more.

There are several publications on heterogeneous catalytic ozonation; however, their conclusions and the comparisons between them are not always consistent due to the variety of applied experimental conditions and the different solid materials used as catalysts. This review attempts to limit the major influencing factors in order to reach more vigorous conclusions. Particularly, it highlights two specific factors/parameters as the most important for the evaluation and comparison of heterogeneous catalytic ozonation processes, i.e., (1) the pH value of the solution and (2) the initial concentration of the (micro-)pollutants. Based on these, the role of Point of Zero Charge (PZC), which concerns the respective solid materials/catalysts in the decomposition of ozone towards the production of oxidative radicals, is highlighted. The discussed observations indicate that for the pH range 6–8 and when the initial organic pollutants’ concentrations are around 1 mg/L (or even lower, i.e., micropollutant), then heterogeneous catalytic ozonation follows a radical mechanism, whereas the applied solid materials show their highest catalytic activity under their neutral charge. Furthermore, carbons are considered as a rather controversial group of catalysts for this process due to their possible instability under intense ozone oxidizing conditions. Full article

(This article belongs to the Special Issue Novel Separation Methods and Technology for Wastewater and Sludge Treatment)

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16 pages, 2001 KiB

Open AccessEditor’s ChoiceArticle

Bioactive Phytochemical Composition of Grape Pomace Resulted from Different White and Red Grape Cultivars

by Petronela Anca Onache, Elisabeta-Irina Geana, Corina Teodora Ciucure, Alina Florea, Dorin Ioan Sumedrea, Roxana Elena Ionete and Ovidiu Tița

Separations 2022, 9(12), 395; https://doi.org/10.3390/separations9120395 - 28 Nov 2022

Cited by 20 | Viewed by 3838

Abstract

Grapes are rich in phenolic compounds, being important for human health with anti-inflammatory, antiatherosclerotic, antimutagenic, anticarcinogenic, antibacterial, antiviral, and antimicrobial activity. The winemaking of the grapes generates significant amounts of waste. These wastes contain bioactive compounds in their biomass that can be used [...] Read more.

Grapes are rich in phenolic compounds, being important for human health with anti-inflammatory, antiatherosclerotic, antimutagenic, anticarcinogenic, antibacterial, antiviral, and antimicrobial activity. The winemaking of the grapes generates significant amounts of waste. These wastes contain bioactive compounds in their biomass that can be used as a source of food improvement or as a source of nutrition supplementation. This study looks at the content of bioactive compounds, the polyphenolic profile, and the antioxidant activity in different white and red grape pomaces. The investigation of bioactive characteristics (total polyphenols, total flavonoids, catechins, tannins, and antioxidant activity) was carried out by UV-Vis spectrophotometric methods, while the individual polyphenolic composition was investigated by target and screening UHPLC-HRMS/MS analysis. Principal components (PCA) and the heat maps analysis allows the discrimination between the grape pomace resulted from white grape cultivars (Muscat Ottonel and Tamaioasa Romaneasca) and red grape pomaces (Cabernet Sauvignon, Merlot, Feteasca Neagra, Burgund Mare, Pinot Nore), with the identification of the specific phenolic compounds for each grape pomace type. Full article

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

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28 pages, 1968 KiB

Open AccessEditor’s ChoiceReview

Metal-Chelating Peptides Separation Using Immobilized Metal Ion Affinity Chromatography: Experimental Methodology and Simulation

by Rachel Irankunda, Jairo Andrés Camaño Echavarría, Cédric Paris, Loïc Stefan, Stéphane Desobry, Katalin Selmeczi, Laurence Muhr and Laetitia Canabady-Rochelle

Separations 2022, 9(11), 370; https://doi.org/10.3390/separations9110370 - 14 Nov 2022

Cited by 16 | Viewed by 7006

Abstract

Metal-Chelating Peptides (MCPs), obtained from protein hydrolysates, present various applications in the field of nutrition, pharmacy, cosmetic etc. The separation of MCPs from hydrolysates mixture is challenging, yet, techniques based on peptide-metal ion interactions such as Immobilized Metal Ion Affinity Chromatography (IMAC) seem [...] Read more.

Metal-Chelating Peptides (MCPs), obtained from protein hydrolysates, present various applications in the field of nutrition, pharmacy, cosmetic etc. The separation of MCPs from hydrolysates mixture is challenging, yet, techniques based on peptide-metal ion interactions such as Immobilized Metal Ion Affinity Chromatography (IMAC) seem to be efficient. However, separation processes are time consuming and expensive, therefore separation prediction using chromatography modelling and simulation should be necessary. Meanwhile, the obtention of sorption isotherm for chromatography modelling is a crucial step. Thus, Surface Plasmon Resonance (SPR), a biosensor method efficient to screen MCPs in hydrolysates and with similarities to IMAC might be a good option to acquire sorption isotherm. This review highlights IMAC experimental methodology to separate MCPs and how, IMAC chromatography can be modelled using transport dispersive model and input data obtained from SPR for peptides separation simulation. Full article

(This article belongs to the Section Bioanalysis/Clinical Analysis)

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40 pages, 3706 KiB

Open AccessEditor’s ChoiceReview

Magnetic Technologies and Green Solvents in Extraction and Separation of Bioactive Molecules Together with Biochemical Objects: Current Opportunities and Challenges

by Xueting Feng, Hang Song, Tenghe Zhang, Shun Yao and Yan Wang

Separations 2022, 9(11), 346; https://doi.org/10.3390/separations9110346 - 3 Nov 2022

Cited by 8 | Viewed by 4591

Abstract

Currently, magnetic technology and green solvents are widely used in chemical engineering, environmental engineering and other fields as they are environmentally friendly, easy to operate and highly efficient. Moreover, a magnetic field has positive effect on many physicochemical processes. However, related new methods, [...] Read more.

Currently, magnetic technology and green solvents are widely used in chemical engineering, environmental engineering and other fields as they are environmentally friendly, easy to operate and highly efficient. Moreover, a magnetic field has positive effect on many physicochemical processes. However, related new methods, materials, strategies and applications in separation science still need to be developed. In this review, a series of meaningful explorations of magnetic technologies for the separation of natural products and biologic objects, including magnetic ionic liquids and other magnetic solvents and fluids, magnetic nanoparticles and magnetic fields, and the development of magnetic separators were reviewed. Furthermore, the difficulties in the application and development of magnetic separation technology were discussed on the basis of comparison and data analysis, especially for the selection of magnetic materials and magnetic field sources. Finally, the progress in the development of magnetic separators was also elaborated for researchers, mainly including that of the new high-efficiency magnetic separator through multi-technology integration and the optimization of traditional magnetic separators, which help current techniques break through their bottleneck as a powerful driving force. Full article

(This article belongs to the Section Purification Technology)

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21 pages, 3869 KiB

Open AccessEditor’s ChoiceArticle

Solubility of CO₂ in 2-Amino-2-methyl-1-propanol (AMP) and 3-(Methylamino)propylamine (MAPA): Experimental Investigation and Modeling with the Cubic-Plus-Association and the Modified Kent-Eisenberg Models

by Giannis Kontos, Maria Anna Soldatou, Evangelos Tzimpilis and Ioannis Tsivintzelis

Separations 2022, 9(11), 338; https://doi.org/10.3390/separations9110338 - 2 Nov 2022

Cited by 5 | Viewed by 2649

Abstract

CO₂ capture attracts significant research efforts in order to reduce the volume of greenhouse gases emitted from fossil fuels combustion. Among the studied processes, chemical absorption represents a mature approach and, in this direction, new solvents, alternatives to monoethanolamine (MEA), have been [...] Read more.

CO₂ capture attracts significant research efforts in order to reduce the volume of greenhouse gases emitted from fossil fuels combustion. Among the studied processes, chemical absorption represents a mature approach and, in this direction, new solvents, alternatives to monoethanolamine (MEA), have been suggested. In this work, the solubility of CO₂ in aqueous solutions of 2-amino-2-methyl-1-propanol (AMP) and 3-(methylamino)propylamine (MAPA), which were recently suggested as constituents of novel phase change solvent mixtures, is experimentally measured at 298, 313, 323, and 333 K and in a wide range of pressures, up to approximately 7 bar. As the available literature experimental data for MAPA aqueous solutions are very limited, the experimental results of this study were compared to respective literature data for AMP, and a very satisfactory agreement was observed. The new experimental data were correlated with the cubic-plus-association (CPA) and the modified Kent-Eisenberg models. It was observed that both models rather satisfactorily correlate the experimental data, with the Kent-Eisenberg model presenting more accurate correlations. Full article

(This article belongs to the Section Analysis of Energies)

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27 pages, 3372 KiB

Open AccessEditor’s ChoiceReview

Purification Technologies for NOx Removal from Flue Gas: A Review

by Zihan Zhu and Bin Xu

Separations 2022, 9(10), 307; https://doi.org/10.3390/separations9100307 - 13 Oct 2022

Cited by 30 | Viewed by 15157

Abstract

Nitrogen oxide (NOx) is a major gaseous pollutant in flue gases from power plants, industrial processes, and waste incineration that can have adverse impacts on the environment and human health. Many denitrification (de-NOx) technologies have been developed to reduce NOx emissions in the [...] Read more.

Nitrogen oxide (NOx) is a major gaseous pollutant in flue gases from power plants, industrial processes, and waste incineration that can have adverse impacts on the environment and human health. Many denitrification (de-NOx) technologies have been developed to reduce NOx emissions in the past several decades. This paper provides a review of the recent literature on NOx post-combustion purification methods with different reagents. From the perspective of changes in the valence of nitrogen (N), purification technologies against NOx in flue gas are classified into three approaches: oxidation, reduction, and adsorption/absorption. The removal processes, mechanisms, and influencing factors of each method are systematically reviewed. In addition, the main challenges and potential breakthroughs of each method are discussed in detail and possible directions for future research activities are proposed. This review provides a fundamental and systematic understanding of the mechanisms of denitrification from flue gas and can help researchers select high-performance and cost-effective methods. Full article

(This article belongs to the Section Environmental Separations)

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16 pages, 1002 KiB

Open AccessEditor’s ChoiceArticle

Plant Poisons in the Garden: A Human Risk Assessment

by Samantha L. Bowerbank, Matteo D. Gallidabino and John R. Dean

Separations 2022, 9(10), 308; https://doi.org/10.3390/separations9100308 - 13 Oct 2022

Cited by 3 | Viewed by 3326

Abstract

A study of the plants, and their associated poisons, in the Poison Garden at The Alnwick Garden was undertaken across a calendar year. By selecting 25 plants in the Poison Garden, we have been able to develop a single chromatographic method for the [...] Read more.

A study of the plants, and their associated poisons, in the Poison Garden at The Alnwick Garden was undertaken across a calendar year. By selecting 25 plants in the Poison Garden, we have been able to develop a single chromatographic method for the determination and quantification of 15 plant toxins by liquid chromatography mass spectrometry (LC-MS). Chromatographic separation was achieved on a C18 column (3.5 µm, 100 × 4.6 mm) with a gradient method using water +0.1% formic acid and methanol +0.1% formic acid. The developed method was validated for precision, linearity, limits of detection and quantification and extraction recoveries. The method showed good linearity with a R² value of >0.995 for all 15 compounds with good precision of 10.7%, 6.7% and 0.3% for the low, medium and high calibration points, respectively. The LC-MS method was used to analyse 25 plant species, as well as their respective parts (i.e., bulb, flower, fruit, leaf, pollen, seed, stem and root), to assess the human risk assessment to children (aged 1 to <2 years) in relation to the plant toxin and its respective LD₅₀. The analysis found that the greatest potential health risks were due to the ingestion of Colchicum autumnale and Atropa belladonna. As a caution, all identified plants should be handled with care with additional precautionary steps to ensure nil contact by children because of the potential likelihood of hand-to-mouth ingestion. Full article

(This article belongs to the Section Environmental Separations)

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17 pages, 3861 KiB

Open AccessEditor’s ChoiceArticle

Evaluation of Pulsed Electric Field-Assisted Extraction on the Microstructure and Recovery of Nutrients and Bioactive Compounds from Mushroom (Agaricus bisporus)

by Mara Calleja-Gómez, Juan Manuel Castagnini, Ester Carbó, Emilia Ferrer, Houda Berrada and Francisco J. Barba

Separations 2022, 9(10), 302; https://doi.org/10.3390/separations9100302 - 10 Oct 2022

Cited by 15 | Viewed by 3302

Abstract

Pulsed electric field (PEF) is a sustainable innovative technology that allows for the recovery of nutrients and bioactive compounds from vegetable matrices. A. bisporus was chosen for its nutritional value and the effect of PEF pretreatment was evaluated using different conditions of electric [...] Read more.

Pulsed electric field (PEF) is a sustainable innovative technology that allows for the recovery of nutrients and bioactive compounds from vegetable matrices. A. bisporus was chosen for its nutritional value and the effect of PEF pretreatment was evaluated using different conditions of electric field (2–3 kV/cm), specific energy (50–200 kJ/kg) and extraction time (0–6 h) to obtain the best conditions for nutrient and bioactive compound extraction. Spectrophotometric methods were used to evaluate the different compounds, along with an analysis of mineral content by inductively coupled plasma mass spectrometry (ICP-MS) and the surface was evaluated using scanning electron microscopy (SEM). In addition, the results were compared with those obtained by conventional extraction (under constant shaking without PEF pretreatment). After evaluating the extractions, the best extraction conditions were 2.5 kV/cm, 50 kJ/kg and 6 h which showed that PEF extraction increased the recovery of total phenolic compounds in 96.86%, carbohydrates in 105.28%, proteins in 11.29%, and minerals such as P, Mg, Fe and Se. These results indicate that PEF pretreatment is a promising sustainable technology to improve the extraction of compounds and minerals from mushrooms showing microporation on the surface, positioning them as a source of compounds of great nutritional interest. Full article

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

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15 pages, 4564 KiB

Open AccessEditor’s ChoiceArticle

Filter Modified with Hydrophilic and Oleophobic Coating for Efficient and Affordable Oil/Water Separation

by Hunter Ross, Huyen Nguyen, Brian Nguyen, Ashton Foster, James Salud, Mike Patino, Yong X. Gan and Mingheng Li

Separations 2022, 9(10), 269; https://doi.org/10.3390/separations9100269 - 28 Sep 2022

Cited by 6 | Viewed by 4682

Abstract

To mitigate the damage of oil spills, a filter modified with a hydrophilic and oleophobic coating is proposed for affordable and efficient oil separation and recovery from water. The sol–gel method was chosen to produce a colloidal suspension of titanium dioxide particles for [...] Read more.

To mitigate the damage of oil spills, a filter modified with a hydrophilic and oleophobic coating is proposed for affordable and efficient oil separation and recovery from water. The sol–gel method was chosen to produce a colloidal suspension of titanium dioxide particles for its ease of production and its versatility in application for many different substrates, including paper and cloth fabric. After immersing the substrates into a titanium-containing solution, three techniques were applied to increase the production of titanium dioxide—microwave-assisted, refrigeration, and ultra-sonication. Contact angle tests were done to investigate the change in the filter’s oleophobicity. The titanium dioxide present on the surface of the filter was amorphous, but all treatment methods showed an improvement in oleophobicity. All treated filters improved oil filtration performance by up to eighty percent. The filters isolated motor oil from a mixture while allowing water to pass through. The coated filters also displayed photocatalytic activity by degrading methylene blue on its surface when exposed to sunlight, demonstrating the filter’s self-cleaning ability. For real-world applications, the filter can be supported by a stainless mesh for enhanced strength and durability. While being dragged through the water, the filter collects the surface oil, allowing water to pass through via gravity. Full article

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

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17 pages, 4397 KiB

Open AccessEditor’s ChoiceReview

Review of Hydrogen Sulfide Removal from Various Industrial Gases by Zeolites

by Tao Yu, Zhuo Chen, Zhendong Liu, Jianhong Xu and Yundong Wang

Separations 2022, 9(9), 229; https://doi.org/10.3390/separations9090229 - 25 Aug 2022

Cited by 13 | Viewed by 6372

Abstract

Hydrogen sulfide (H₂S) removal from various industrial gases is crucial because it can cause huge damage to humans, the environment, and industrial production. Zeolite possesses huge specific surface area and well-developed pore structure, making it a promising adsorbent for H₂ [...] Read more.

Hydrogen sulfide (H₂S) removal from various industrial gases is crucial because it can cause huge damage to humans, the environment, and industrial production. Zeolite possesses huge specific surface area and well-developed pore structure, making it a promising adsorbent for H₂S removal. This review attempts to comprehensively compile the current studies in the literature on H₂S removal in gas purification processes using zeolites, including experimental and simulation studies, mechanism theory, and practical applications. Si/Al ratio, cations of zeolite, industrial gas composition and operating conditions, and H₂S diffusion in zeolites affect desulfurization performance. However, further efforts are still needed to figure out the influence rules of the factors above and H₂S removal mechanisms. Based on an extensive compilation of literature, we attempt to shed light on new perspectives for further research in the future. Full article

(This article belongs to the Special Issue Advances in Separation Engineering)

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26 pages, 955 KiB

Open AccessEditor’s ChoiceReview

An Overview of Methods for L-Dopa Extraction and Analytical Determination in Plant Matrices

by Carmen Tesoro, Filomena Lelario, Rosanna Ciriello, Giuliana Bianco, Angela Di Capua and Maria Assunta Acquavia

Separations 2022, 9(8), 224; https://doi.org/10.3390/separations9080224 - 17 Aug 2022

Cited by 15 | Viewed by 7191

Abstract

L-dopa is a precursor of dopamine used as the most effective symptomatic drug treatment for Parkinson’s disease. Most of the L-dopa isolated is either synthesized chemically or from natural sources, but only some plants belonging to the Fabaceae family contain significant amounts of [...] Read more.

L-dopa is a precursor of dopamine used as the most effective symptomatic drug treatment for Parkinson’s disease. Most of the L-dopa isolated is either synthesized chemically or from natural sources, but only some plants belonging to the Fabaceae family contain significant amounts of L-dopa. Due to its low stability, the unambiguous determination of L-dopa in plant matrices requires appropriate technologies. Several analytical methods have been developed for the determination of L-dopa in different plants. The most used for quantification of L-dopa are mainly based on capillary electrophoresis or chromatographic methods, i.e., high-performance liquid chromatography (HPLC), coupled to ultraviolet-visible or mass spectrometric detection. HPLC is most often used. This paper aims to give information on the latest developments in the chemical study of L-dopa, emphasizing the extraction, separation and characterization of this compound by chromatographic, electrochemical and spectral techniques. This study can help select the best possible strategy for determining L-dopa in plant matrices using advanced analytical methods. Full article

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

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18 pages, 4429 KiB

Open AccessEditor’s ChoiceArticle

Metabolomic and Proteomic Profile of Dried Hop Inflorescences (Humulus lupulus L. cv. Chinook and cv. Cascade) by SPME-GC-MS and UPLC-MS-MS

by Paola Nezi, Vittoria Cicaloni, Laura Tinti, Laura Salvini, Matteo Iannone, Sara Vitalini and Stefania Garzoli

Separations 2022, 9(8), 204; https://doi.org/10.3390/separations9080204 - 6 Aug 2022

Cited by 18 | Viewed by 3974

Abstract

Hop (Humulus lupulus L.) is grown mainly for the production of beer. The flowers of the female plant give it the bitter taste and pungent aroma. There are a large number of hop varieties differing in their α-acid content, essential oil levels [...] Read more.

Hop (Humulus lupulus L.) is grown mainly for the production of beer. The flowers of the female plant give it the bitter taste and pungent aroma. There are a large number of hop varieties differing in their α-acid content, essential oil levels and odor profiles. Aside from their use in brewing, more recently, hops have been used for the pharmacological properties of its derivatives that are of great importance to the pharmaceutical industry. Hop is known to have a fairly complex chemistry characterized by the presence of a variety of sesquiterpenoids, diterpenoids and triterpenoids, phytoestrogens and flavonoids. Additionally, considering the countless applications in the pharmacological sector in recent years, a chemical characterization of the different cultivars is essential to better identify the source of specific secondary metabolites. For this purpose, the dried inflorescences of two hop cultivars, Chinook and Cascade, were investigated using Solid-Phase Microextraction-Gas Chromatography-Mass Spectrometry and Liquid Chromatography-Tandem Mass Spectrometry (SPME-GC-MS and LC-MS-MS) to describe their metabolomic and proteomic profile. Furthermore, thanks to an in-depth statistical survey, it was possible to carry out a comparative study highlighting interesting implications deriving from this investigative study. Full article

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

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20 pages, 2698 KiB

Open AccessEditor’s ChoiceArticle

Simultaneous Extraction of Four Antibiotic Compounds from Soil and Water Matrices

by Alison M. Franklin, Danielle M. Andrews, Clinton F. Williams and John E. Watson

Separations 2022, 9(8), 200; https://doi.org/10.3390/separations9080200 - 2 Aug 2022

Cited by 7 | Viewed by 3741

Abstract

The incidence of antibiotic resistance is on the rise and becoming a major health concern. Analyzing the presence of antibiotic compounds in the environment is critical for determining the potential health effects for humans, animals, and ecosystems. For this study, methods were developed [...] Read more.

The incidence of antibiotic resistance is on the rise and becoming a major health concern. Analyzing the presence of antibiotic compounds in the environment is critical for determining the potential health effects for humans, animals, and ecosystems. For this study, methods were developed to simultaneously isolate and quantify four antibiotics important in human medicine (sulfamethoxazole—SMX, trimethoprim—TMP, lincomycin—LIN, and ofloxacin—OFL) in water and soil matrices. For water analysis, different solid phase extraction (SPE) cartridges (Oasis HLB plus and Phenomenex Strata-X) were compared. The Oasis HLB Plus SPE cartridge provided the highest and most consistent recoveries with 118 ± 5%, 86 ± 4%, 83 ± 5%, and 75 ± 1% for SMX, TMP, LIN, and OFL, respectively. For soil analysis, different pre-treatments (grinding and freeze-drying) and soil extraction methodologies (liquid-solid extraction and accelerated solvent extraction (ASE)) were compared. The ASE system resulted in the highest overall recoveries of SMX, TMP, LIN, and OFL with an optimal extracting solution of acetonitrile/water (v/v, 50:50, pH 2.8). When the soil was ground and freeze-dried, trimethoprim recovery increased and when soil was ground, but not freeze-dried, LIN and OFL recoveries increased, while sulfamethoxazole recoveries decreased when soil was ground and freeze-dried. Based on this research, matrix characteristics, especially pH, as well as the pKa’s and functional groups of the antibiotics need to be carefully considered when attempting to extract antibiotic compounds from a water or soil environment. Full article

(This article belongs to the Special Issue Analytical Separation Techniques for Environmental Analysis)

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13 pages, 3769 KiB

Open AccessEditor’s ChoiceArticle

Fog Droplet Collection by Corona Discharge in a Needle–Cylinder Electrostatic Precipitator with a Water Cooling System

by Hui Fu, Wenyi Xu, Zhen Liu and Keping Yan

Separations 2022, 9(7), 169; https://doi.org/10.3390/separations9070169 - 6 Jul 2022

Cited by 9 | Viewed by 3571

Abstract

In this study, a needle–cylinder electrostatic precipitator with a water cooling system was designed to enhance the harvest of atmospheric water in wet flue gas. The effects of flow rate, temperature and particles on the collection of fog droplets were investigated. Meanwhile, the [...] Read more.

In this study, a needle–cylinder electrostatic precipitator with a water cooling system was designed to enhance the harvest of atmospheric water in wet flue gas. The effects of flow rate, temperature and particles on the collection of fog droplets were investigated. Meanwhile, the energy efficiency of water collection was analyzed at different voltages. The results show that the current decreases with the increase of air relative humidity under the same voltage, and the breakdown voltage increases obviously. Concurrently, by appropriately reducing the wet flue gas flow velocity, the residence time of fog droplets in the electric field can be increased, fully charging the droplets and improving the water collection efficiency. Moreover, experiments revealed that through decreasing the flue gas temperature, both the water collection rate and energy efficiency can be improved. In addition, the presence of particles in wet gas can improve the water collection rate by 5~8% at different discharge voltages. Finally, based on energy efficiency analysis, with the increase of voltage, although the water collection rate increased, the energy efficiency decreased. Full article

(This article belongs to the Section Environmental Separations)

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20 pages, 5122 KiB

Open AccessEditor’s ChoiceArticle

Comparative Study of Natural Antioxidants from Glycine max, Anethum graveolensand Pimpinella anisum Seed and Sprout Extracts Obtained by Ultrasound-Assisted Extraction

by Fanica Balanescu, Anna Cazanevscaia Busuioc, Andreea Veronica Dediu Botezatu, Steluta Gosav, Sorin Marius Avramescu, Bianca Furdui and Rodica Mihaela Dinica

Separations 2022, 9(6), 152; https://doi.org/10.3390/separations9060152 - 13 Jun 2022

Cited by 10 | Viewed by 3050

Abstract

The study aimed to evaluate the antioxidant potential of sprout and seed extracts from three species of plants, namely Glycine max (GMsp-sprouts, GMsd-seeds), Anethum graveolens (AGsp-sprouts, AGsd-seeds) and Pimpinella anisum (PAsp-sprouts, PAsd-seeds), which are widely accepted by consumers and have various applications in [...] Read more.

The study aimed to evaluate the antioxidant potential of sprout and seed extracts from three species of plants, namely Glycine max (GMsp-sprouts, GMsd-seeds), Anethum graveolens (AGsp-sprouts, AGsd-seeds) and Pimpinella anisum (PAsp-sprouts, PAsd-seeds), which are widely accepted by consumers and have various applications in food flavoring, and also in natural medical treatments in the pharmaceutical industries. These plants are rich in valuable compounds that show a remarkable antioxidant power and are associated with many health benefits. Ethanol extracts were obtained by ultrasound-assisted extraction and they were comparatively evaluated for their in vitro antioxidant properties. The extracts were characterized by HPTLC, HPLC-DAD, total phenol content (TPC), total flavonoid content (TFC) analysis and antioxidant activities with different assays, such as total antioxidant capacity (TAC), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical cation decolorization assay (ABTS), 1,1-diphenyl 1-2-picryl-hydrazyl (DPPH) and iron binding ability of chelators. Our results showed that the sprout and seed extracts of the studied plants exhibited a high content of phytochemicals and promising antioxidant properties. The highest polyphenols content was detected for AGsd (53.02 ± 0.57 mg/g DW), PAsd (48.75 ± 0.34 mg/g DW) and the highest flavonoids content for PAsp (26.84 ± 0.57 mg/g DW). Moreover, the presence of valuable compounds was demonstrated by using HPTLC, FT-IR and HPLC-DAD techniques. In order to have a better understanding of the relationship between the biological properties and the electronic structure, a molecular modelling study of genistein was also conducted. Our approach to the comparative assessment of these three plant species was based on a priori knowledge from literature data; however, this study demonstrated that these plant extracts of seeds and also sprouts are excellent sources of natural antioxidants. Significant additional differences that were found in the phytochemical composition could be exploited in future research for pharmaceutical purposes. Full article

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12 pages, 678 KiB

Open AccessEditor’s ChoiceArticle

HPLC-MS, GC and NMR Profiling of Bioactive Lipids of Human Milk and Milk of Dairy Animals (Cow, Sheep, Goat, Buffalo, Camel, Red Deer)

by Kirill Lagutin, Andrew MacKenzie, Stephen Bloor, Dawn Scott and Mikhail Vyssotski

Separations 2022, 9(6), 145; https://doi.org/10.3390/separations9060145 - 7 Jun 2022

Cited by 14 | Viewed by 4076

Abstract

For non-bovine milks, information regarding bioactive lipids is fragmented, unreliable or unavailable. The purpose of the current study was to analyse bioactive lipids in the milk of dairy animals using modern analytical methods to achieve the most reliable results. Bioactive lipids in human [...] Read more.

For non-bovine milks, information regarding bioactive lipids is fragmented, unreliable or unavailable. The purpose of the current study was to analyse bioactive lipids in the milk of dairy animals using modern analytical methods to achieve the most reliable results. Bioactive lipids in human milk were also analysed and used as a reference. A suite of modern analytical methods was employed, namely High Performance Liquid Chromatography-Mass Spectrometry (HPLC-MS), Gas Chromatography (GC) and Nuclear Magnetic Resonance (NMR). The total lipid content was determined, and phospholipid, fatty acid, neutral glycosphingolipids and ganglioside (GM3 and GD3) levels were measured. Lipid classes in selected milks were reliably characterised for the first time, including gangliosides in deer, camel and sheep; cerebrosides in deer, camel and buffalo; plasmalogens in deer, buffalo and goat and phospholipids in deer. Our study demonstrated the advantage of utilising a range of analytical techniques in order to characterise a diverse set of bioactive lipids. Full article

(This article belongs to the Special Issue Development of Highly Efficient Separation-Based Analytical Methods for Food Integrity Assurance)

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15 pages, 2685 KiB

Open AccessEditor’s ChoiceArticle

Measuring Vitamin D₃ Metabolic Status, Comparison between Vitamin D Deficient and Sufficient Individuals

by Laura de los Santos Castillo-Peinado, Mónica Calderón-Santiago, Aura Dulcinea Herrera-Martínez, Soraya León-Idougourram, María Ángeles Gálvez-Moreno, Rafael Luis Sánchez-Cano, Roger Bouillon, Jose Manuel Quesada-Gómez and Feliciano Priego-Capote

Separations 2022, 9(6), 141; https://doi.org/10.3390/separations9060141 - 3 Jun 2022

Cited by 6 | Viewed by 2366

Abstract

The main branch of vitamin D₃ metabolism involves several hydroxylation reactions to obtain mono-, di- and trihydroxylated metabolites, including the circulating and active forms—25(OH)D₃ and 1,25(OH)₂D₃, respectively. However, most clinical trials strictly target the determination of 25(OH)D [...] Read more.

The main branch of vitamin D₃ metabolism involves several hydroxylation reactions to obtain mono-, di- and trihydroxylated metabolites, including the circulating and active forms—25(OH)D₃ and 1,25(OH)₂D₃, respectively. However, most clinical trials strictly target the determination of 25(OH)D₃ to offer a view of the metabolic status of vitamin D₃. Due to the growing interest in expanding this restricted view, we have developed a method for measuring vitamin D₃ metabolism by determination of vitamin D₃, 25(OH)D₃, 24,25(OH)₂D₃, 1,25(OH)₂D₃ and 1,24,25(OH)₃D₃ in human plasma. The method was based on SPE–LC–MS/MS with a large volume injection of human plasma (240 µL). Detection of di- and trihydroxymetabolites, found at the picogram per milliliter level, was attained by the combined action of high preconcentration and clean-up effects. The method allows obtaining information about ratios such as the known vitamin D metabolite ratio (24,25(OH)₂D₃/25(OH)D₃), which can provide complementary views of vitamin D₃ metabolic status. The method was applied to a cohort of obese patients and a reference cohort of healthy volunteers to find metabolic correlations between target analytes as well as differences as a function of vitamin D levels within and between cohorts. Full article

(This article belongs to the Special Issue Chromatographic Analysis of Biological Samples)

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12 pages, 1274 KiB

Open AccessEditor’s ChoiceArticle

Validation of an Analytical Method for the Determination of Thiabendazole in Various Food Matrices

by Sun-Il Choi, Xionggao Han, Se-Jeong Lee, Xiao Men, Geon Oh, Doo-Sik Lee and Ok-Hwan Lee

Separations 2022, 9(6), 135; https://doi.org/10.3390/separations9060135 - 27 May 2022

Cited by 12 | Viewed by 3760

Abstract

In many countries, thiabendazole is used as a fungicide to prevent the decay of food and to lengthen storage periods. However, in Korea, thiabendazole is unauthorised and does not have standards or specifications for use as a food additive. In this study, a [...] Read more.

In many countries, thiabendazole is used as a fungicide to prevent the decay of food and to lengthen storage periods. However, in Korea, thiabendazole is unauthorised and does not have standards or specifications for use as a food additive. In this study, a simple analytical method was developed and validated using the HPLC–PDA method to detect thiabendazole in foods frequently consumed in South Korea. The calibration curve was obtained using samples of solid and liquid foods containing banana and citrus fruits containing concentrations in the range of 0.31–20.00 μg/mL with a satisfactory coefficient of determination (R²) of 0.999. The limit of detection (LOD) values for the solid and liquid food samples were 0.009 and 0.017 μg/mL, respectively, and the limit of quantification (LOQ) values were 0.028 and 0.052 μg/mL. The intra-day and inter-day precision values were less than 1.33% (relative standard deviation), and the recoveries of thiabendazole from spiked solid and liquid food samples ranged from 93.61 to 98.08% at concentration levels of 2.5, 5, and 10 μg/mL. In addition, the expanded uncertainties of the measu-rements ranged from 0.57 to 3.12%. These results showed that the developed method was appropriate for the quantitative analysis of thiabendazole in solid and liquid foods containing banana and citrus fruits. Full article

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

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18 pages, 7895 KiB

Open AccessEditor’s ChoiceArticle

Modified Polyethersulfone Ultrafiltration Membrane for Enhanced Antifouling Capacity and Dye Catalytic Degradation Efficiency

by Mingming Wang, Feiyun Sun, Haojie Zeng, Xiaoli Su, Guofei Zhou, Hao Liu and Dingyu Xing

Separations 2022, 9(4), 92; https://doi.org/10.3390/separations9040092 - 4 Apr 2022

Cited by 12 | Viewed by 3797

Abstract

Catalytic membranes, as a combination of heterogeneous advanced oxidation and membrane technology reaction systems, have important application prospects in the treatment of dyes and other organics. In practical applications, it is still challenging to construct catalytic membranes with excellent removal efficiency and fouling [...] Read more.

Catalytic membranes, as a combination of heterogeneous advanced oxidation and membrane technology reaction systems, have important application prospects in the treatment of dyes and other organics. In practical applications, it is still challenging to construct catalytic membranes with excellent removal efficiency and fouling mitigation. Herein, molybdenum disulfide-iron oxyhydroxide (MoS₂-FeOOH) was fabricated using iron oxide and MoS₂ nanoflakes, which were synthesized by the hydrothermal method. Furthermore, by changing the concentration of MoS₂-FeOOH, the MoS₂-FeOOH/polyethersulfone (PES) composite ultrafiltration membrane was obtained with improved hydrophilicity, permeability, and antifouling capacity. The pure water flux of the composite membrane reached 385.3 L/(m²·h), which was 1.7 times that of the blank PES membrane. Compared with the blank membrane, with the increase of MoS₂-FeOOH content, the MoS₂-FeOOH/PES composite membranes had better adsorption capacity and catalytic performance, and the membrane with 3.0% MoS₂-FeOOH content (M4) could be achieved at a 60.2% methylene blue (MB) degradation rate. In addition, the membrane flux recovery ratio (FRR) of the composite membrane also increased from 25.6% of blank PES membrane (M0) to more than 70% after two cycles of bovine serum albumin (BSA) filtration and hydraulic cleaning. The membrane with 2.25% MoS₂-FeOOH content (M3) had the best antifouling performance, with the largest FRR and the smallest irreversible ratio (R_ir). Catalytic self-cleaning of the composite membrane M3 recovered 95% of the initial flux with 0.1 mol/L H₂O₂ cleaning. The MoS₂-FeOOH/PES composite membranes with the functions of excellent rejection and antifouling capacity have a good prospect in the treatment of printing and dyeing wastewater composed of soluble dyes. Full article

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

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21 pages, 1176 KiB

Open AccessEditor’s ChoiceReview

Separation of Serum and Plasma Proteins for In-Depth Proteomic Analysis

by Joseph Paul and Timothy D. Veenstra

Separations 2022, 9(4), 89; https://doi.org/10.3390/separations9040089 - 1 Apr 2022

Cited by 19 | Viewed by 12134

Abstract

There are probably no biological samples that did more to spur interest in proteomics than serum and plasma. The belief was that comparing the proteomes of these samples obtained from healthy and disease-affected individuals would lead to biomarkers that could be used to [...] Read more.

There are probably no biological samples that did more to spur interest in proteomics than serum and plasma. The belief was that comparing the proteomes of these samples obtained from healthy and disease-affected individuals would lead to biomarkers that could be used to diagnose conditions such as cancer. While the continuing development of mass spectrometers with greater sensitivity and resolution has been invaluable, the invention of strategic strategies to separate circulatory proteins has been just as critical. Novel and creative separation techniques were required because serum and plasma probably have the greatest dynamic range of protein concentration of any biological sample. The concentrations of circulating proteins can range over twelve orders of magnitude, making it a challenge to identify low-abundance proteins where the bulk of the useful biomarkers are believed to exist. The major goals of this article are to (i) provide an historical perspective on the rapid development of serum and plasma proteomics; (ii) describe various separation techniques that have made obtaining an in-depth view of the proteome of these biological samples possible; and (iii) describe applications where serum and plasma proteomics have been employed to discover potential biomarkers for pathological conditions. Full article

(This article belongs to the Special Issue Separations and Analysis of Proteins in Biological Samples)

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21 pages, 1708 KiB

Open AccessEditor’s ChoiceArticle

Adverse Effects of Arsenic Uptake in Rice Metabolome and Lipidome Revealed by Untargeted Liquid Chromatography Coupled to Mass Spectrometry (LC-MS) and Regions of Interest Multivariate Curve Resolution

by Miriam Pérez-Cova, Romà Tauler and Joaquim Jaumot

Separations 2022, 9(3), 79; https://doi.org/10.3390/separations9030079 - 18 Mar 2022

Cited by 12 | Viewed by 4112

Abstract

Rice crops are especially vulnerable to arsenic exposure compared to other cereal crops because flooding growing conditions facilitates its uptake. Besides, there are still many unknown questions about arsenic’s mode of action in rice. Here, we apply two untargeted approaches using liquid chromatography [...] Read more.

Rice crops are especially vulnerable to arsenic exposure compared to other cereal crops because flooding growing conditions facilitates its uptake. Besides, there are still many unknown questions about arsenic’s mode of action in rice. Here, we apply two untargeted approaches using liquid chromatography coupled to mass spectrometry (LC-MS) to unravel the effects on rice lipidome and metabolome in the early stages of growth. The exposure is evaluated through two different treatments, watering with arsenic-contaminated water and soil containing arsenic. The combination of regions of interest (ROI) and multivariate curve resolution (MCR) strategies in the ROIMCR data analyses workflow is proposed and complemented with other multivariate analyses such as partial least square discriminant analysis (PLS-DA) for the identification of potential markers of arsenic exposure and toxicity effects. The results of this study showed that rice metabolome (and lipidome) in root tissues seemed to be more affected by the watering and soil treatment. In contrast, aerial tissues alterations were accentuated by the arsenic dose, rather than with the watering and soil treatment itself. Up to a hundred lipids and 40 metabolites were significantly altered due to arsenic exposure. Major metabolic alterations were found in glycerophospholipids, glycerolipids, and amino acid-related pathways. Full article

(This article belongs to the Section Chromatographic Separations)

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23 pages, 4583 KiB

Open AccessEditor’s ChoiceReview

The Bright and Dark Sides of Reactive Oxygen Species Generated by Copper–Peptide Complexes

by Urszula K. Komarnicka, Monika K. Lesiów, Maciej Witwicki and Alina Bieńko

Separations 2022, 9(3), 73; https://doi.org/10.3390/separations9030073 - 11 Mar 2022

Cited by 7 | Viewed by 3970

Abstract

Copper ions bind to biomolecules (e.g., peptides and proteins) playing an essential role in many biological and physiological pathways in the human body. The resulting complexes may contribute to the initiation of neurodegenerative diseases, cancer, and bacterial and viral diseases, or act as [...] Read more.

Copper ions bind to biomolecules (e.g., peptides and proteins) playing an essential role in many biological and physiological pathways in the human body. The resulting complexes may contribute to the initiation of neurodegenerative diseases, cancer, and bacterial and viral diseases, or act as therapeutics. Some compounds can chemically damage biological macromolecules and initiate the development of pathogenic states. Conversely, a number of these compounds may have antibacterial, antiviral, and even anticancer properties. One of the most significant current discussions in Cu biochemistry relates to the mechanisms of the positive and negative actions of Cu ions based on the generation of reactive oxygen species, including radicals that can interact with DNA molecules. This review aims to analyze various peptide–copper complexes and the mechanism of their action. Full article

(This article belongs to the Section Bioanalysis/Clinical Analysis)

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