Separations

11 pages, 2888 KiB

Open AccessFeature PaperArticle

A Green and Cost-Effective Chromatographic Method for the Measurement of the Activity of Human Serum Carnosinase

by Chiara de Giacomi and Luca Regazzoni

Separations 2023, 10(8), 460; https://doi.org/10.3390/separations10080460 - 21 Aug 2023

Cited by 1 | Viewed by 1167

Carnosinase (i.e., CN1; E.C. 3.4.13.20) is an enzyme found in the sera of higher primates. CN1 preferentially catalyzes the hydrolysis of natural, orally adsorbed histidine dipeptides like carnosine (i.e., β-alanyl-L-histidine). This is the reason why carnosine has a limited use as a human [...] Read more.

Carnosinase (i.e., CN1; E.C. 3.4.13.20) is an enzyme found in the sera of higher primates. CN1 preferentially catalyzes the hydrolysis of natural, orally adsorbed histidine dipeptides like carnosine (i.e., β-alanyl-L-histidine). This is the reason why carnosine has a limited use as a human food supplement or pharmacological agent, despite the promising results obtained in experiments on animal models of human diseases. Herein, an assay is reported for the measurement of serum CN1 activity. The method is intended for the screening of CN1 inhibitors able to enhance carnosine bioavailability in humans. The method was developed to monitor serum hydrolytic activity via the quantitation of one of the products of carnosine hydrolysis (i.e., histidine). Separation was achieved without using organic solvents by means of ion chromatography (IC), whereas detection was provided by UV spectroscopy. The assay herein reported is a green and cost-effective alternative to a recently published method based on hydrophilic interaction liquid chromatography (HILIC) and mass spectrometry (MS). The results show that such a method produces reliable measurements of serum hydrolytic activity and can be used for the screening of CN1 inhibitors. Full article

(This article belongs to the Special Issue Advanced Methods for Separation and Analysis of Natural Products)

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16 pages, 3797 KiB

Open AccessArticle

Optimization of QuEChERS Method for Antibiotic Residue Analysis in Animal Foods via Response Surface Methodology

by Xiaoqiong Wu, Yun Lin, Xiang Zhang, Nan Ouyang and Ying Zhou

Separations 2023, 10(8), 459; https://doi.org/10.3390/separations10080459 - 21 Aug 2023

Cited by 3 | Viewed by 1711

Abstract

The present study employed a modified QuEChERS method to systematically analyze the presence of fifteen quinolone and seven tetracycline antibiotic residues in local animal food. Additionally, a multi-level four-factor Box–Behnken design (BBD) within the framework of response surface methodology (RSM) was utilized to [...] Read more.

The present study employed a modified QuEChERS method to systematically analyze the presence of fifteen quinolone and seven tetracycline antibiotic residues in local animal food. Additionally, a multi-level four-factor Box–Behnken design (BBD) within the framework of response surface methodology (RSM) was utilized to evaluate the factors impacting the detection efficiency of the sample pretreatment procedure. Optimization was performed via Design Expert^® 10.0.3, and the factors, including the volume of the acetonitrile, the addition of formic acid, the duration of the extraction, and the addition of EDTA, were combined with experimental design until an optimal solution was reached. Finally, the sample was tested via ultra-high performance liquid chromatography-quadrupole-linear ion trap mass spectrometry (UPLC/MS/MS) in both multiple reaction monitoring (MRM) and enhanced product ion (EPI) scan modes on a QTRAP^® 5500 instrument (AB SCIEX instruments, Framingham, MA, USA). The overall average recoveries from actual samples fortified with 22 antibiotics at three levels ranged from 73.8% to 98.5% based on the use of matrix-fortified calibration, with variations ranging from 5.80 to 12.4% (n = 6). The limits of detection and quantification were 0.3 μg kg⁻¹ and 1.0 μg kg⁻¹, respectively. Lastly, the modified method was applied to practical sample analysis in the daily risk monitoring and assessment of food safety with satisfactory stability and robustness. Full article

(This article belongs to the Topic Application of Liquid Chromatography-Mass Spectrometry and Related Techniques)

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15 pages, 971 KiB

Open AccessArticle

Impact of Cumin (Cuminum cyminum) Incorporation on the Generation of Heterocyclic Aromatic Amines in Meatballs

by Elif Ekiz, Adem Savaş, Eyad Aoudeh, Zeynep Elbir, Emel Oz, Charalampos Proestos, Naushad Ahmad and Fatih Oz

Separations 2023, 10(8), 458; https://doi.org/10.3390/separations10080458 - 21 Aug 2023

Cited by 3 | Viewed by 1356

Abstract

In the current study, the impacts of using cumin (0.5% and 1%, w/w) in beef meatballs on heterocyclic aromatic amines (HAAs) formation and some quality characteristics when cooked at 150 and 250 °C were investigated. It was found that using [...] Read more.

In the current study, the impacts of using cumin (0.5% and 1%, w/w) in beef meatballs on heterocyclic aromatic amines (HAAs) formation and some quality characteristics when cooked at 150 and 250 °C were investigated. It was found that using of cumin at different ratios in beef meatballs showed a significant (p < 0.01) effect on pH, thiobarbituric acid reactive (TBARS) value, and total HAA. The cooking process significantly (p < 0.01) affected the meatballs’ water content, pH, and TBARS values, while the cooking loss and total HAA content of meatballs were significantly (p < 0.01) affected by cooking temperature. It was found that the cumin usage rate in meatballs increased the pH value, while it was found to decrease the TBARS value. As expected, the cooking process was associated with a reduction in water, while it was found to result in an increase in the pH and TBARS values. On the other hand, both cooking temperature and cumin addition to meatballs led to an increase in their total HAA content. Diverse samples exhibited detectable levels of IQx, MeIQx, MeIQ, and PhIP compounds. The presence of MeIQx compound was found in all samples, except for the control group cooked at 150 °C. Additionally, the use of 0.5% and 1% cumin in meatballs cooked at temperature of 250 °C had an inhibitory effect on MeIQx compound. Our results revealed that the incorporation of cumin in the meatballs resulted in an increase in the total HAA content, likely due to its prooxidant effect. However, it was found that the use of cumin at certain rates could reduce the formation of MeIQx compound with an antioxidant effect. However, in this study found that even if 100 g of meatballs with the highest concentration of total HAA were consumed, the maximum HAA exposure limit value (0–15 µg/day) was not exceeded. Full article

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15 pages, 334 KiB

Open AccessArticle

UHPLC-ToF-MS as a High-Resolution Mass Spectrometry Tool for Veterinary Drug Quantification in Milk

by Marta Leite, Ana Rita Marques, Ana Sofia Vila Pouca, Silvia Cruz Barros, Jorge Barbosa, Fernando Ramos, Isabel Maria Afonso and Andreia Freitas

Separations 2023, 10(8), 457; https://doi.org/10.3390/separations10080457 - 21 Aug 2023

Cited by 1 | Viewed by 1826

Abstract

Milk is one of the most widely consumed foods in the world, despite the increasing consumption of plant-based alternatives. Although rich in nutrients and believed by consumers to be free of undesirable contaminants, milk, whether of animal or plant origin, is not always [...] Read more.

Milk is one of the most widely consumed foods in the world, despite the increasing consumption of plant-based alternatives. Although rich in nutrients and believed by consumers to be free of undesirable contaminants, milk, whether of animal or plant origin, is not always free from residues of chemical substances, including veterinary medicines. For instance, in intensive livestock production, antibiotics are often used to treat animals or, illicitly, to improve their growth performance, which can lead to their presence in the final food. Additionally, the continuous use of veterinary drugs in intensive animal production can lead to their occurrence in agricultural soils and therefore are absorbed by plants as another source of entering the food chain. An effective and accurate multi-detection quantitative screening method to analyze 89 antibiotics in milk was optimized by ultra-high-performance liquid chromatography coupled with a time-of-flight detector (UHPLC-ToF-MS) and further validated in accordance with the Commission Implementing Regulation (CIR) 808/2021 and the International Council for Harmonization (ICH) guidelines on the validation of analytical procedures. Apart from the specific parameters required by CIR 808/2021, the aim was to access the lower limits of the method, limits of detection (LoD) and quantification (LoQ), regardless of the maximum residue limits (MRLs) defined in the legislation. The method was then applied in the analysis of 32 supermarket samples, resulting in four positive findings, including one plant-based sample. The antibiotics found were from the macrolides and sulphonamides families. Nevertheless, the concentrations detected were below the established maximum residue level (MRL). 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)

11 pages, 2195 KiB

Open AccessFeature PaperArticle

Determining the Hydrophobicity Index of Protected Amino Acids and Common Protecting Groups

by Varshitha Gavva, Othman Al Musaimi, Colin Bent and Daryl R. Williams

Separations 2023, 10(8), 456; https://doi.org/10.3390/separations10080456 - 20 Aug 2023

Cited by 3 | Viewed by 2944

Abstract

Peptides are in great demand in the pharmaceutical arena and a majority of these peptides contain 20 or more amino acids. They are infrequently synthesised using the fragment condensation approach. A key limitation in adopting this approach more commonly is that protected peptide [...] Read more.

Peptides are in great demand in the pharmaceutical arena and a majority of these peptides contain 20 or more amino acids. They are infrequently synthesised using the fragment condensation approach. A key limitation in adopting this approach more commonly is that protected peptide fragments with high purity are often required prior to the final condensation steps. It is hypothesized that understanding the hydrophobic nature of the protected amino acids will assist with designing optimal fragment purification processes when needed. Whilst a myriad of hydrophobicity indices are reported in the literature for unprotected amino acids, the literature lacks any data regarding the protected amino acids which form the key precursor for the fragment condensation task. In this current study, hydrophobicity indices for protected amino acids with common α-amino and sidechain protecting groups were experimentally determined. Different positions for each amino acid within the peptide chain were considered, namely at the C-terminal and N-terminal as well as internal positions. These data give deep insights on the hydrophobicity of each amino acid with respect to its position in the peptide chain. The data acquired in this research facilitated the prediction of the retention time of protected peptide fragments with an uncertainty of less than ±1.5%. Full article

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

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14 pages, 2556 KiB

Open AccessArticle

Evaluation of BPA and Bis-GMA Release from Recent Dental Composite Materials by LC-MS/MS

by Lígia Lopes-Rocha, Virgínia M. F. Gonçalves, Sara C. Cunha, José O. Fernandes, Teresa Pinho and Maria Elizabeth Tiritan

Separations 2023, 10(8), 455; https://doi.org/10.3390/separations10080455 - 18 Aug 2023

Cited by 1 | Viewed by 3369

Abstract

Bisphenol-A (BPA) is a xenoestrogen widely used as a synthetic precursor of resin monomers. There is arise need to acquire BPA-free resin-matrix composites to prevent the health effects of BPA. Six composites with distinctive manufacturer specifications were considered to evaluate the degree of [...] Read more.

Bisphenol-A (BPA) is a xenoestrogen widely used as a synthetic precursor of resin monomers. There is arise need to acquire BPA-free resin-matrix composites to prevent the health effects of BPA. Six composites with distinctive manufacturer specifications were considered to evaluate the degree of release of BPA and bisphenol A-Diglycidyl Methacrylate (Bis-GMA) in a dental composite. The light-cured resin-matrix specimens (n = 5 for each composite type) were incubated at 37 °C in 1 mL of a 75% ethanol–water solution in a sealed amber glass vial for 7 days. The 75% ethanol–water solution was replaced daily and immediately frozen (−20 °C) until liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. BPA was not detected in any studied resin-based materials. However, Bis-GMA was detected in almost all the studied samples during the experiment, except AF and BF. The highest Bis-GMA concentration was released from ED at 67.43 ng/mL, followed by BE, FS, and NC with 40.75 ng/mL, 8.30 ng/mL, and 0.94 ng/mL, respectively. There is a clear need for more precise and standardized analytical methods to assess the short- and long-term release of resin-based materials. Furthermore, manufacturers should be obliged to provide complete details of the chemical composition of dental products and to promote the development of materials without estrogenic potential. Full article

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

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17 pages, 4969 KiB

Open AccessArticle

Molecularly Imprinted Polymer-Based Nanoporous Carbon Nanocomposite for Effective Adsorption of Hg(II) Ions from Aqueous Suspensions

by Lawal Abubakar, Nor Azah Yusof, Abdul Halim Abdullah, Faruq Mohammad, Mohd Hanif Wahid, Suhainie Ismail, Zulaiha Abdul Rahim, Hamad A. Al-Lohedan and Ahmed A. Soleiman

Separations 2023, 10(8), 454; https://doi.org/10.3390/separations10080454 - 17 Aug 2023

Viewed by 1336

Abstract

Due to the release of hazardous heavy metals from various industries, water pollution has become one of the biggest challenges for environmental scientists today. Mercury Hg(II) is regarded as one of the most toxic heavy metals due to its ability to cause cancer [...] Read more.

Due to the release of hazardous heavy metals from various industries, water pollution has become one of the biggest challenges for environmental scientists today. Mercury Hg(II) is regarded as one of the most toxic heavy metals due to its ability to cause cancer and other health issues. In this study, a tailor-made modern eco-friendly molecularly imprinted polymer (MIP)/nanoporous carbon (NC) nanocomposite was synthesized and examined for the uptake of Hg(II) using an aqueous solution. The fabrication of the MIP/NC nanocomposite occurred via bulk polymerization involving the complexation of the template, followed by polymerization and, finally, template removal. Thus, the formed nanocomposite underwent characterizations that included morphological, thermal degradation, functional, and surface area analyses. The MIP/NC nanocomposite, with a high specific surface area of 884.9 m²/g, was evaluated for its efficacy towards the adsorptive elimination of Hg(II) against the pH solution changes, the dosage of adsorbent, initial concentration, and interaction time. The analysis showed that a maximum Hg(II) adsorption effectiveness of 116 mg/g was attained at pH 4, while the Freundlich model fitted the equilibrium sorption result and was aligned with pseudo-second-order kinetics. Likewise, thermodynamic parameters like enthalpy, entropy, and Gibbs free energy indicated that the adsorption was consistent with spontaneous, favorable, and endothermic reactions. Furthermore, the adsorption efficiency of MIP/NC was also evaluated against a real sample of condensate from the oil and gas industry, showing an 87.4% recovery of Hg(II). Finally, the synthesized MIP/NC showed promise as a selective adsorbent of Hg(II) in polluted environments, suggesting that a variety of combined absorbents of different precursors is recommended to evaluate heavy metal and pharmaceutical removals. Full article

(This article belongs to the Special Issue Advanced Techniques in the Separation Processes and Development of Novel Adsorbents)

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33 pages, 2982 KiB

Open AccessReview

MALDI-TOF MS: A Promising Analytical Approach to Cancer Diagnostics and Monitoring

by Patrícia Sousa, Laurentina Silva, Catarina Luís, José S. Câmara and Rosa Perestrelo

Separations 2023, 10(8), 453; https://doi.org/10.3390/separations10080453 - 14 Aug 2023

Cited by 2 | Viewed by 4975

Abstract

Cancer remains the second most common cause of death after cardiovascular diseases, accounting for nearly 10 million deaths in 2020. Although the incidence of cancer increases considerably with age, the cancer burden can also be reduced and have a high chance of cure [...] Read more.

Cancer remains the second most common cause of death after cardiovascular diseases, accounting for nearly 10 million deaths in 2020. Although the incidence of cancer increases considerably with age, the cancer burden can also be reduced and have a high chance of cure through early detection, appropriate treatment, and care of patients. The development of high-throughput analytical approaches, like matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), contributes to identifying a pool of proteins/peptides as putative biomarkers for the early detection, diagnosis, and tumor progression. The purpose of the current review is to present an updated outline of recent proteome/peptidome research to establish putative cancer biomarkers using MALDI-TOF MS and highlight the applicability of statistical analysis in the oncology field. The pros and cons of MALDI-TOF MS application on cancer diagnostics and monitoring will be discussed, as well as compared with tandem mass spectrometry (MS/MS)-based proteomics (e.g., liquid chromatography–tandem mass spectrometry). In addition, pre-analytical (e.g., sample quality control) and analytical (e.g., sample pre-treatment, instrumental analytical conditions) properties that influence the robustness of MALDI-TOF MS data will be also discussed. Full article

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17 pages, 800 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Solid–Liquid Extraction of Bioactive Molecules from White Grape Skin: Optimization and Near-Infrared Spectroscopy

by Tea Sokač Cvetnić, Korina Krog, Maja Benković, Tamara Jurina, Davor Valinger, Jasenka Gajdoš Kljusurić, Ivana Radojčić Redovniković and Ana Jurinjak Tušek

Separations 2023, 10(8), 452; https://doi.org/10.3390/separations10080452 - 14 Aug 2023

Cited by 2 | Viewed by 1490

Abstract

In this work, the solid–liquid extraction of bioactive molecules from grape skin was performed using water as the extraction solvent. The effects of extraction time (t = 60, 75, and 90 min), extraction temperature (T = 40, 60, and 80 °C), [...] Read more.

In this work, the solid–liquid extraction of bioactive molecules from grape skin was performed using water as the extraction solvent. The effects of extraction time (t = 60, 75, and 90 min), extraction temperature (T = 40, 60, and 80 °C), solid–liquid phase ratio (S/L = 10, 20, and 30 g/L), and mixing speed (rpm = 250, 500, and 750 1/min) on the total dissolved solids, extraction yield, concentration of total polyphenols, and antioxidant activity were determined using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) methods. According to response surface modeling, the optimal extraction conditions were t = 75 min, T = 80 °C, S/L = 30 g/L, and rpm = 750 1/min, and under optimal process conditions, 8.38 mg_GAE/g_d.m. was obtained. Furthermore, the potential of near-infrared (NIR) spectroscopy coupled with artificial neural network (ANN) modeling for prediction of the physical and chemical properties of prepared extracts was also analyzed. The use of ANN modeling demonstrated highly favorable correlations between the NIR spectra and all the variables tested, particularly the total dissolved solids (TDS) and antioxidant activity measured using the FRAP method. As a result, ANN modeling proved to be a valuable tool for predicting the concentration of total polyphenols, the antioxidant activity, and the extraction yield of a plant extract based on its NIR spectra. Full article

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

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12 pages, 2682 KiB

Open AccessArticle

Study on Treatment Performance of Desulfurization Wastewater by Zero-Valent Iron Fenton-like Process

by Ziguo Liu, Wei Zhou, Xianli Liu, Xuefen Yang, Wei Yang and Han Zheng

Separations 2023, 10(8), 451; https://doi.org/10.3390/separations10080451 - 14 Aug 2023

Cited by 1 | Viewed by 1178

Abstract

In this study, the zero-valent iron Fenton reagent (ZVI Fenton-like) system was combined with the chemical precipitation method for the deep treatment of desulfurization wastewater from coal-fired power plants, and the chemical oxygen demand (COD) was used as the evaluation criterion for organic [...] Read more.

In this study, the zero-valent iron Fenton reagent (ZVI Fenton-like) system was combined with the chemical precipitation method for the deep treatment of desulfurization wastewater from coal-fired power plants, and the chemical oxygen demand (COD) was used as the evaluation criterion for organic matter in the desulfurization wastewater. The effects of reaction time, H₂O₂ dosage, zero-valent iron dosage, pH, and reaction temperature were also investigated. The results showed that the COD concentration of the effluent was the lowest when the running time of the ZVI Fenton-like reagent system was 1 h, the dosage of H₂O₂ was 33.3 mg·L⁻¹, the dosage of iron was 0.075 g·L⁻¹, the pH was 4.5~6.5, the reaction temperature was 35 °C, the COD concentration of the wastewater was the lowest and its operating conditions were the best, and the internal reaction mechanism was finally deduced. In summary, the zero-valent iron Fenton reagent system provides a new idea for the treatment of desulfurization wastewater from coal-fired power plants. Full article

(This article belongs to the Special Issue Separation Technology in Bioprocess for Environmental Remediation)

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17 pages, 2674 KiB

Open AccessArticle

A Fast LC-MS/MS Methodology for Estimating Savolitinib in Human Liver Microsomes: Assessment of Metabolic Stability Using In Vitro Metabolic Incubation and In Silico Software Analysis

by Mohamed W. Attwa, Haitham AlRabiah, Ali S. Abdelhameed and Adnan A. Kadi

Separations 2023, 10(8), 450; https://doi.org/10.3390/separations10080450 - 14 Aug 2023

Cited by 1 | Viewed by 1389

Abstract

Savolitinib (Orpathys^®), was developed by (HUTCHMED (Shanghai, China) and, AstraZeneca (Gaithersburg, Maryland, USA), is an inhibitor of the c-Met receptor tyrosine kinase that is orally bioavailable. It was designed for the treatment of pillary and clear-cell renal-cell carcinoma (RCC), colorectal cancer, [...] Read more.

Savolitinib (Orpathys^®), was developed by (HUTCHMED (Shanghai, China) and, AstraZeneca (Gaithersburg, Maryland, USA), is an inhibitor of the c-Met receptor tyrosine kinase that is orally bioavailable. It was designed for the treatment of pillary and clear-cell renal-cell carcinoma (RCC), colorectal cancer, gastric cancer, and metastatic non-small-cell lung cancer (NSCLC). The current work aimed to develop a rapid, specific, green, and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) methodology for estimating savolitinib (SVB) in human liver microsomes (HLMs) with application to an in vitro metabolic stability assessment of SVB in HLMs. The validation steps of the current LC-MS/MS methodology in the HLMs were carried out following US FDA bioanalytical method validation guidelines including sensitivity, selectivity, linearity, accuracy, stability, precision, extraction recovery, and matrix effect. SVB and olmutinib (OLM) were chromatographically separated on an Eclipse Plus C8 column using an isocratic mobile phase. SVB parent ions were generated using the positive mode of an electrospray ionization (ESI) source. SVB daughter ions were detected and quantified using the multiple reaction monitoring (MRM) mode of a triple quadrupole mass analyser. The constructed SVB calibration curve showed linearity over the range from 1 to 3000 ng/mL. The interday and intraday accuracy and precision of the developed LC-MS/MS analytical methodology were −6.67%–4.11% and −0.51%–8.75%, respectively. A lower limit of quantification (LLOQ) of 0.87 ng/mL confirmed the sensitivity of the established method. Furthermore, the eco-scale methodology using the in silico AGREE software was used for the greenness assessment of the current LC-MS/MS method, and the outcomes showed that the established method was very eco-friendly. The intrinsic clearance (Cl_int) and in vitro half-life (t_1/2) of SVB were 33.05 mL/min/kg and 24.54 min, respectively. SVB exhibited a moderate extraction ratio. The current study is the first to establish and validate LC-MS/MS for estimating SVB and assessing the metabolic stability of SVB. Full article

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15 pages, 2507 KiB

Open AccessArticle

Analytical and Preparative Separation of Softwood Lignans by Supercritical Fluid Chromatography

by Nikolay V. Ul’yanovskii, Aleksandra A. Onuchina, Denis V. Ovchinnikov, Anna V. Faleva, Natalia S. Gorbova and Dmitry S. Kosyakov

Separations 2023, 10(8), 449; https://doi.org/10.3390/separations10080449 - 13 Aug 2023

Cited by 5 | Viewed by 1277

Abstract

Lignans are widespread polyphenolic secondary plant metabolites possessing high biological activity. One of the most promising industrial-scale sources of such compounds is coniferous knotwood, containing a large number of polyphenolic compounds. Their use in pharmaceutical and other industries is limited by the difficulty [...] Read more.

Lignans are widespread polyphenolic secondary plant metabolites possessing high biological activity. One of the most promising industrial-scale sources of such compounds is coniferous knotwood, containing a large number of polyphenolic compounds. Their use in pharmaceutical and other industries is limited by the difficulty in obtaining high-purity preparations from plant material and the requirement of advanced separation techniques. In this study, supercritical fluid chromatography on polar stationary phases was proposed for the efficient separation and identification of spruce, pine, fir, and larch knotwood extractives. Among the six tested sorbents, the best results were shown by silica with grafted diol and 2-ethylpyridine groups under conditions of gradient elution with a carbon dioxide–methanol mobile phase, which ensured the efficient retention and separation of analytes due to donor–acceptor interactions. Scaling up the method on a DIOL stationary phase provided a semi-preparative separation of extractives within 30 min to obtain 14 individual compounds with a purity of 90–99% and yields from 0.3 to 51% of the dry extract. These included eight lignans (nortrachelogenin, matairesinol, oxomatairesinol, α-conidendrin, 5-hydroxymatairesinol and its isomer, lariciresinol, and secoisolariciresinol), two oligolignans, three stilbenes (pinosylvin and its methyl ester, pterostilbene), and flavonoid taxifolin. The developed approach is distinguished with low operational costs, low consumption of organic solvents, environmental safety, and it is fully consistent with the principles of green chemistry. Full article

(This article belongs to the Section Chromatographic Separations)

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16 pages, 2688 KiB

Open AccessArticle

Expression, Purification and Characterization of a Novel Rusticyanin from the Psychrotolerant Acidithiobacillus ferrivorans

by Yuandong Liu, Lixiang Chen, Xiangdong Shangguan, Jingying Ouyang, Jiayu He, Kan Wang, Yan Tong, Runlan Yu, Weimin Zeng, Xueling Wu, Li Shen and Guanzhou Qiu

Separations 2023, 10(8), 448; https://doi.org/10.3390/separations10080448 - 13 Aug 2023

Cited by 1 | Viewed by 1489

Abstract

Rusticyanin plays a crucial role in ferrous oxidation of sulfide minerals during bioleaching for industrial metal extraction. Diverse isoforms of rusticyanin have been found, but until now, except for type-A rusticyanin, other isoforms or sources of rusticyanin have been scarcely investigated. Here, a [...] Read more.

Rusticyanin plays a crucial role in ferrous oxidation of sulfide minerals during bioleaching for industrial metal extraction. Diverse isoforms of rusticyanin have been found, but until now, except for type-A rusticyanin, other isoforms or sources of rusticyanin have been scarcely investigated. Here, a rusticyanin (gene locus 0470) from the psychrophilic Acidithiobacillus ferrivorans was gene-cloned, expressed, purified, and assembled in vitro. All forms of the protein exhibit extreme acid stability, even at pH 0.3. The stability of the protein is obviously enhanced after binding of the copper cofactor; the oxidation state is more stable than the reduced state. The protein has characteristic UV-vis peaks and EPR signals similar to type-A or type-B rusticyanin but is different with a small position shift and an obvious intensity change. The vibrational spectrum of the apoprotein was more different than these between the oxidation and reduced states of the protein. The ferrous oxidation kinetic rate constant of the protein is obviously faster than that of both the type-A and type-B rusticyanins previously reported. Further bioinformatics analysis reveal their changes in sequence and molecule: the mutations related to the peculiar shield belt mostly account for the variation in the properties of the protein, and the classification of the protein as a new isoform, type-C rusticyanin, is proposed. Full article

(This article belongs to the Special Issue Application of Microbial Metallurgy Process in Metal Extraction)

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15 pages, 4002 KiB

Open AccessArticle

Comparison of Miniaturized Chromatographic Columns and 96-Well Plates for Automated Antibody Purification under Economic and Sustainable Aspects

by Anna Bach, Heidi Fleischer and Kerstin Thurow

Separations 2023, 10(8), 447; https://doi.org/10.3390/separations10080447 - 11 Aug 2023

Viewed by 2086

Abstract

Therapeutic antibodies are an area of major interest in treating infectious diseases, autoimmune diseases, and cancer. Efficient purification strategies are required to discover and produce antibodies, representing a significant cost driver. Miniaturization and automation of the chromatographic purification process may contribute to cost [...] Read more.

Therapeutic antibodies are an area of major interest in treating infectious diseases, autoimmune diseases, and cancer. Efficient purification strategies are required to discover and produce antibodies, representing a significant cost driver. Miniaturization and automation of the chromatographic purification process may contribute to cost reduction. In this article, miniaturized chromatographic columns and 96-well filter plates are used to purify an IgG antibody from cell cultures and are compared in terms of quality, cost, and sustainability. The validation results of the two miniaturized chromatographic antibody purification methods indicate high efficacy and are comparable except for minor differences in yield. The lowest cost per sample can be obtained with the miniaturized chromatographic columns, as annual throughput can be maximized with the miniaturized plates. By evaluating sustainability, significant reductions in laboratory waste produced during antibody purification can be shown, along with an increase in employee safety by using the automation system. Overall, the comparison of results shows that, in the development of new purification strategies, the type of implementation has a decisive influence on the outcomes in terms of recovery, cost-effectiveness, and sustainability. Full article

(This article belongs to the Special Issue Analysis of Pharmaceuticals: Sample Preparation and Chromatography/Separation)

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17 pages, 6542 KiB

Open AccessArticle

Representative Elementary Volume Estimation and Neural Network-Based Prediction of Change Rates of Dense Non-Aqueous Phase Liquid Saturation and Dense Non-Aqueous Phase Liquid–Water Interfacial Area in Porous Media

by Zhou Cheng, Guoping Lu, Ming Wu and Qusheng Li

Separations 2023, 10(8), 446; https://doi.org/10.3390/separations10080446 - 10 Aug 2023

Cited by 1 | Viewed by 1184

Abstract

Investigation of the change rate for contaminant parameters is important to characterize dense non-aqueous phase liquid (DNAPL) transport and distribution in groundwater systems. In this study, four experiments of perchloroethylene (PCE) migration are conducted in two-dimensional (2D) sandboxes to characterize change rates of [...] Read more.

Investigation of the change rate for contaminant parameters is important to characterize dense non-aqueous phase liquid (DNAPL) transport and distribution in groundwater systems. In this study, four experiments of perchloroethylene (PCE) migration are conducted in two-dimensional (2D) sandboxes to characterize change rates of PCE saturation (S_o) and PCE–water interfacial area (A_OW) under different conditions of salinity, surface active agent, and heterogeneity. Associated representative elementary volume (REV) of the change rate of S_o (S_o rate) and change rate of A_OW (A_OW rate) is derived over the long-term transport process through light transmission techniques. REV of S_o rate (SR-REV) and REV of A_OW rate (AR-REV) are estimated based on the relative gradient error (

ε_{g}^{i}

). Regression analysis is applied to investigate the regularity, and a model based on a back-propagation (BP) neural network is built to simulate and predict the frequencies of SR-REV and AR-REV. Experimental results indicated the salinity, surface active agent, and heterogeneity are important factors that affect the S_o rate, A_OW rate, SR-REV, and AR-REV of the PCE plume in porous media. The first moment of the PCE plume along the vertical direction is decreased under conditions of high salinity, surface active agent, and heterogeneity, while these factors have different effects on the second moment of the PCE plume. Compared with the salinity and surface active agent, heterogeneity has the greatest effect on the GTP, the distributions of the S_o rate and A_OW rate along the depth, and d_M, d_I. For SR-REV, the standard deviation is increased by the salinity, surface active agent, and heterogeneity. Simultaneously, the salinity and heterogeneity lead to lower values of the mean value of SR-REV, while the surface active agent increases the mean value of SR-REV. However, the mean and standard deviation of AR-REV have no apparent difference under different experimental conditions. These findings reveal the complexity of PCE transport and scale effect in the groundwater system, which have important significance in improving our understanding of DNAPL transport regularity and promoting associated prediction. Full article

(This article belongs to the Section Environmental Separations)

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23 pages, 5456 KiB

Open AccessArticle

High-Degree Oxidative Desulfurization of a Commercial Marine Fuel Using Deep Eutectic Solvents and Their Recycling Process

by Olga Thoda, Efstratios Svinterikos, Konstantinos Miltiadis Sakkas, Anastasia Maria Moschovi and Iakovos Yakoumis

Separations 2023, 10(8), 445; https://doi.org/10.3390/separations10080445 - 9 Aug 2023

Cited by 2 | Viewed by 1946

Abstract

Escalating environmental concerns have dictated the need to develop innovative methods for efficiently desulfurizing marine fuels (heavy fuel oils). In this work, the oxidative desulfurization method using deep eutectic solvents (DESs) was applied to reduce the sulfur content in a commercially available heavy [...] Read more.

Escalating environmental concerns have dictated the need to develop innovative methods for efficiently desulfurizing marine fuels (heavy fuel oils). In this work, the oxidative desulfurization method using deep eutectic solvents (DESs) was applied to reduce the sulfur content in a commercially available heavy fuel oil (HFO) below 0.5 wt.%, as current regulations demand. Initially, the S-compounds in the fuel were oxidized using an oxidative mixture of H₂O₂ with carboxylic acid (either acetic or formic acid). Subsequently, the oxidized S-compounds were extracted from the fuel using a series of environmentally friendly deep eutectic solvents (DESs), the best of which was proven to be a mixture of choline chloride with ethylene glycol at a 1/2 molar ratio. The process was optimized by investigating the effect of several process parameters on the desulfurization efficiency, namely, the H₂O₂/S molar ratio, the H₂O₂/acid molar ratio, the acid type, the oxidation temperature and oxidation time, the solvent/fuel mass ratio, the extraction time, and the extraction temperature. A desulfurization efficiency of 75.7% was achieved under the optimized conditions, reducing the S content in the fuel to 0.33 wt.%. Furthermore, different methods to recycle the DESs were investigated, and consecutive desulfurization and solvent regeneration cycles were performed. The most efficient recycling method was determined to be the anti-solvent addition of excess water, which resulted in 89.5% DES purification by causing precipitation of the dissolved solids. After three cycles of desulfurization and regeneration using different recycling routes, it was found that the regeneration degree declines gradually; however, it is more than 79.3% in all cases. Full article

(This article belongs to the Collection State of the Art in Separation and Analysis of Energies)

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18 pages, 1141 KiB

Open AccessEditor’s ChoiceArticle

The Development and Validation of a Targeted LC-HRAM-MS/MS Methodology to Separate and Quantify p-Synephrine and m-Synephrine in Dietary Supplements and Herbal Preparations

by Celine Vanhee, Sophia Barhdadi, Angélique Kamugisha, Tanika Van Mulders, Kevin Vanbrusselen, Marie Willocx and Eric Deconinck

Separations 2023, 10(8), 444; https://doi.org/10.3390/separations10080444 - 9 Aug 2023

Cited by 2 | Viewed by 1605

Abstract

Dietary supplements containing Citrus aurantium or p-synephrine remain very popular in Europe and the United States of America (USA). They are primarily sold as weight loss enhancers, although their efficacy and the safety are still under scrutiny. To this end, several countries [...] Read more.

Dietary supplements containing Citrus aurantium or p-synephrine remain very popular in Europe and the United States of America (USA). They are primarily sold as weight loss enhancers, although their efficacy and the safety are still under scrutiny. To this end, several countries have set maximum threshold levels of p-synephrine that are permitted in dietary supplements. Moreover, there have also been reports of possible chemical adulteration of these supplements with the synthetic positional isomer, m-synephrine, known to be used as a medicinal product. Therefore, it is pivotal for regulatory agencies to be able to discriminate between the two positional isomers and also quantify the amount of each when encountered in dietary supplements. Here, we present the development and the validation of a simple and fast “dilute and shoot” procedure, employing liquid chromatographic (LC) separation in combination with high-resolution accurate mass (HRAM) tandem mass spectroscopy (LC-HRAM-MS/MS) to separate these two isomers and subsequently quantify them. The quantification methodology has been validated using the “total error approach”, applying accuracy profiles, and is consequently compliant with ISO17025. Moreover, ten real-life samples, either purchased online or encountered by Belgian regulatory agencies, were analyzed using the described procedure. Startlingly, only one sample out of ten was compliant with Belgian legislation in terms of labeling, the presence of a batch number, expiration date and dosage (with a tolerated error of ±20%). Moreover, three samples also contained banned substances such as yohimbine and sibutramine. Full article

(This article belongs to the Special Issue Recent Advances and Trends in Dietary Supplement Analysis)

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13 pages, 3176 KiB

Open AccessArticle

In-Line Measurement of Extraction Process by Slug Flow and Determination of Mass Transfer Parameters

by Takamichi Okamoto and Akinori Muto

Separations 2023, 10(8), 443; https://doi.org/10.3390/separations10080443 - 8 Aug 2023

Viewed by 1600

Abstract

The primary objective of this study was to pragmatically implement an extraction process using slug flow, wherein two immiscible phases, aqueous and oil, are alternatively channeled through a conduit to encourage mass exchange across the interface. To facilitate this, we introduced and empirically [...] Read more.

The primary objective of this study was to pragmatically implement an extraction process using slug flow, wherein two immiscible phases, aqueous and oil, are alternatively channeled through a conduit to encourage mass exchange across the interface. To facilitate this, we introduced and empirically validated an in-line technique to precisely quantify the length of the slug and the potential extraction concentration of the two aforementioned phases. The length of the slug and its concentration were ascertained through conductivity, utilizing platinum wire as the electrode. This method consistently produced results with a maximum error margin of ±5%. Using this apparatus, we determined key mass transfer parameters, including the overall mass transfer coefficient. Notably, as the linear velocity amplified, so did the extraction rate. These findings present a significant opportunity for enhancing the efficiency of the extraction process and enabling its optimization. Full article

(This article belongs to the Topic Advances in Chemistry and Chemical Engineering)

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18 pages, 3120 KiB

Open AccessArticle

Effects of Catha edulis (Khat) on the Pharmacokinetics of Metformin in Diabetic Rats Using UPLC/MS/MS Analysis and Its Impact on Hepatic CYP450 Enzymes

by Ali S. Alqahtani, Mohammad Khalid Parvez, Abdulaziz M. Alqahtani, Omer I. Fantoukh, Rashed N. Herqash, Ehab M. Elzayat, Fahd A. Nasr, Essam Ezzeldin, Mousallam M. Almousallam and Mohammad Raish

Separations 2023, 10(8), 442; https://doi.org/10.3390/separations10080442 - 8 Aug 2023

Cited by 1 | Viewed by 1735

Abstract

Catha edulis Forsk., commonly known as Khat, is a stimulant plant that is chewed in the Horn of Africa and the southern regions of the Arabian Peninsula. It is often used alongside conventional drugs, but there is a lack of research on [...] Read more.

Catha edulis Forsk., commonly known as Khat, is a stimulant plant that is chewed in the Horn of Africa and the southern regions of the Arabian Peninsula. It is often used alongside conventional drugs, but there is a lack of research on its interactions with other drugs. In this study, our aim was to investigate the possibility of an herb–drug interaction between KT extract and metformin (MT) by exploring the effect of KT on the in vivo pharmacokinetics of MT in diabetic Wistar albino rats and monitoring blood glucose levels through time intervals, comparing when MT was given alone and co-administered with KT. Rats were given 500 mg/kg of KT extract and 300 mg/kg of MT daily for 7 days. The pharmacokinetic parameters of MT were analyzed using UPLC-MS/MS. The quantification was conducted using multiple reaction monitoring (MRM) in positive ion mode. The transitions used were (m/z) 130.006→59.939 for MT and 260.125→116.018 for propranolol as an internal standard (IS). An Acquity UPLC BEH HSS T3 C18 column was used with isocratic elution, and the mobile phase was formic acid (0.1%): acetonitrile (70:30 v/v) at a flow rate of 0.25 mL/min. In addition, the study delved into the in vitro impact of KT on the CYP3A4 enzyme, seeking to identify any potential disruptions in MT’s metabolism that could alter its pharmacokinetics. The effect of KT extract on CYP3A4 enzyme activity was investigated using fluorescence-based enzyme assays and a CYP3A4 Inhibitor Screening Kit. The results indicated that the combined treatment showed increased systemic exposure to MT, with C_max and AUC levels increasing by 33.42% and 45.23%, respectively. Additionally, the combination treatment led to significantly lower fasting blood glucose (FBG) levels compared to the groups treated with MT alone. It was found that at a concentration of 500 µg/mL, the CYP3A4 enzyme activity was maximally suppressed by approximately 57%, while at 250 µg/mL, it was inhibited by almost 50%. In comparison, the standard Ketoconazole only inhibited CYP3A4 activity by approximately 58%. Therefore, the in vitro results suggest that KT extract has the potential to affect CYP3A4 activity at high doses. In conclusion, the combination treatment resulted in a significant increase in MT’s blood sugar-lowering effects. Therefore, it is important to be aware of this potential interaction and to monitor blood sugar levels closely when using KT alongside MT. Full article

(This article belongs to the Section Chromatographic Separations)

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20 pages, 336 KiB

Open AccessReview

Enhanced Adsorption of Chromate and Arsenate Ions from Contaminated Water with Emphasis on Polyethylenimine Modified Materials: A Review

by Maria Xanthopoulou and Ioannis A. Katsoyiannis

Separations 2023, 10(8), 441; https://doi.org/10.3390/separations10080441 - 7 Aug 2023

Cited by 7 | Viewed by 1736

Abstract

Heavy metals in water pose a great threat to human health, and water treatment remains a critical issue globally. Among various water treatment techniques, adsorption has been proven to be an excellent way to remove heavy metals from water due to its advantages, [...] Read more.

Heavy metals in water pose a great threat to human health, and water treatment remains a critical issue globally. Among various water treatment techniques, adsorption has been proven to be an excellent way to remove heavy metals from water due to its advantages, like low cost, availability, profitability, ease of operation, and efficiency. Heavy metals such as chromium and arsenic are present in water in the form of anions, while many common adsorbents, such as biochar and activated carbons, cellulose, chitosan, clays, and silica, tend to acquire a negative surface charge. The surface charge of the adsorbent plays a major role in its interaction with heavy metal ions. Polyethylenimine is a polymer with a high cationic charge density. Modification of these adsorbents with polyethylenimine results in higher selectivity for these anions. The adsorption capacity is related to the efficiency of the introduction of polyethylenimine, which depends on the surface properties of the adsorbent. This review focuses on the effect of modification with polyethylenimine on the adsorption capacity of common adsorbents for the removal of heavy metal ions, such as chromate and arsenate, from water. Full article

(This article belongs to the Special Issue Removal of Metals or Other Toxic Substances from Wastewaters by Natural Sorbents)

13 pages, 4509 KiB

Open AccessArticle

Enhancement of Photocatalytic Rhodamine B Degradation over Magnesium–Manganese Baring Extracted Iron Oxalate from Converter Slag

by Chitiphon Chuaicham, Jirawat Trakulmututa, Sulakshana Shenoy, Vellaichamy Balakumar, Phatchada Santawaja, Shinji Kudo, Karthikeyan Sekar and Keiko Sasaki

Separations 2023, 10(8), 440; https://doi.org/10.3390/separations10080440 - 3 Aug 2023

Cited by 1 | Viewed by 1547

Abstract

In this work, iron oxalate from converter slag (FeOX-Slag) was produced by extraction of iron from converter slag using oxalic acid, followed by photo-reduction. The FeOX-Slag sample was subjected to various characterization techniques, including X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy with [...] Read more.

In this work, iron oxalate from converter slag (FeOX-Slag) was produced by extraction of iron from converter slag using oxalic acid, followed by photo-reduction. The FeOX-Slag sample was subjected to various characterization techniques, including X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), ultraviolet–visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence spectroscopy (PL), X-ray absorption near-edge structure spectroscopy (XANES), and X-ray photoelectron spectroscopy (XPS), in order to gain insights into its physicochemical properties. Also, to compare the photocatalytic activity of the FeOX-Slag, commercial iron oxide (Fe₂O₃) was used as a precursor to produce normal iron oxalate (FeOX-Fe₂O₃). The obtained FeOX-Slag was applied to the photocatalytic degradation of rhodamine B (RhB), a model organic contaminant in wastewater, compared with the FeOX-Fe₂O₃. Using the produced FeOX-Slag, we were able to degrade RhB more than 98% within 90 min at a reaction rate constant of about 3.6 times faster than FeOX-Fe₂O₃. Photoluminescence results confirmed the less recombination of the electron–hole pairs in FeOX-Slag, compared to FeOX-Fe₂O₃, which may be due to the defect structure of iron oxalate by guest metal impurities. The higher separation and transportation of photogenerated electron–hole pairs cause the enhancement of the degradation photocatalytic RhB degradation activity of the FeOX-Slag. In addition, The FeOX-Slag showed higher light absorption ability than FeOX-Fe₂O₃, resulting in the enhancement of the RhB degradation performance. Thus, the optical properties and the results from the activity tests led to the proposal that FeOX-Slag may be used in a photocatalytic degradation process for RhB under light irradiation. Full article

(This article belongs to the Section Environmental Separations)

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2 pages, 154 KiB

Open AccessEditorial

Chromatographic Separations

by Victoria Samanidou

Separations 2023, 10(8), 439; https://doi.org/10.3390/separations10080439 - 2 Aug 2023

Cited by 1 | Viewed by 1510

Abstract

The topic of chromatographic separations is a recent addition to the Separations journal [...] Full article

(This article belongs to the Section Chromatographic Separations)

17 pages, 3527 KiB

Open AccessArticle

Removal of Pb(II) from Aqueous Solution and Adsorption Kinetics of Corn Stalk Biochar

by Wenling Yang, Chaoyang Lu, Bo Liang, Chaohui Yin, Gao Lei, Baitao Wang, Xiaokai Zhou, Jing Zhen, Shujing Quan and Yanyan Jing

Separations 2023, 10(8), 438; https://doi.org/10.3390/separations10080438 - 2 Aug 2023

Cited by 9 | Viewed by 2008

Abstract

In this work, the Pb adsorption and removal ability of biochar from simulated Pb(II)-contaminated wastewater, adsorption isotherms, kinetics, and thermodynamics were studied. Adsorption characteristics of biochar on Pb(II) were analyzed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscope [...] Read more.

In this work, the Pb adsorption and removal ability of biochar from simulated Pb(II)-contaminated wastewater, adsorption isotherms, kinetics, and thermodynamics were studied. Adsorption characteristics of biochar on Pb(II) were analyzed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscope with energy dispersive spectrometer (SEM-EDS). The influence of the pH of the solution, the contact time, and the biochar dose on the removal of Pb(II) were investigated by single-factor design and response surface analysis. With the increase in biochar dose from 2 g/L to 4 g/L in wastewater, the Pb(II) amount adsorbed on biochar reduced from 21.3 mg/g to 17.5 mg/g. A weakly acidic environment was more conducive to the ligand exchange between Pb(II) ions and biochar. Pb(II) adsorption kinetics of biochar showed that the Pseudo-first-order model was more suitable than other employed models to describe the adsorption process. During the isothermal adsorption process, Langmuir and Freundlich’s isotherms fitted the adsorption data very well (R² > 96%). The Pb (II) adsorption onto biochar was spontaneous in the specified temperature range (298–318 K) and the process was exothermic. Simultaneously, the optimal conditions were a pH of 5, a contact time of 255 min, and a biochar dose of 3 g/L, under which the maximum predicted Pb(II) removal efficiency was 91.52%. Full article

(This article belongs to the Special Issue Carbon-Based Materials for Contaminant Removal)

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11 pages, 1944 KiB

Open AccessArticle

Optimization of the Preparation of Hydrophilic Poly(DHPMA-co-MBA) Monolithic Capillary Columns: A New Support for Affinity Chromatography

by Julie Gil, Gaëtan Passalacqua, Adrien Deloche, François-Xavier Vidal, Vincent Dugas and Claire Demesmay

Separations 2023, 10(8), 437; https://doi.org/10.3390/separations10080437 - 2 Aug 2023

Cited by 2 | Viewed by 1213

Abstract

In miniaturized affinity chromatography, the development of hydrophilic organic monoliths with reduced non-specific interactions and high-protein grafting capacity remains a hot topic. In this work, we propose the one-step synthesis of a diol organic monolith to replace the gold-standard epoxy-based organic monoliths (which [...] Read more.

In miniaturized affinity chromatography, the development of hydrophilic organic monoliths with reduced non-specific interactions and high-protein grafting capacity remains a hot topic. In this work, we propose the one-step synthesis of a diol organic monolith to replace the gold-standard epoxy-based organic monoliths (which require post-modification, namely hydrolysis, prior to use). The synthesis of this new monolith builds upon the use of N-N’-Methylenebis(acrylamide) (MBA), as a hydrophilic crosslinker, and 2,3-dihydroxypropyl methacrylate (DHPMA), a diol monomer that eliminates the time-consuming epoxy ring opening step and its associated side reactions. The optimization of one-step synthesis parameters led to a monolith with a satisfactory permeability ((4.8 ± 0.5) × 10⁻¹⁴ m²), high efficiency (117,600 plates/m at optimum flow velocity (u_opt = 0.09 cm s⁻¹)) and reduced non-specific interactions. It is exemplified by its separation ability in the HILIC mode (separation of nucleosides), and by the retention data set of 41 test solutes, which were used to evaluate the non-specific interactions. This new poly(DHPMA-co-MBA) monolith has not only hydrophilic surface properties, but also improved protein grafting capacity compared to the glycidyl-based monolith (13 ± 0.7 pmol cm⁻¹). The potential of this monolith is illustrated in affinity chromatography, where the concanavalin ligands are ranked according to their K_d values. Full article

(This article belongs to the Section Chromatographic Separations)

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13 pages, 1578 KiB

Open AccessArticle

Chemometric Approach of Different Extraction Conditions on Scavenging Activity of Helichrisym italicum (Roth) G. Don Extracts

by Branislava Teofilović, Filip Balaž, Milica Karadžić Banjac, Nevena Grujić-Letić, Emilia Gligorić, Strahinja Kovačević, Sanja Podunavac-Kuzmanović and Srđan Stojanović

Separations 2023, 10(8), 436; https://doi.org/10.3390/separations10080436 - 2 Aug 2023

Cited by 1 | Viewed by 1173

Abstract

Helichrysum italicum (Roth) G. Don is widely used as a liver stimulant and diuretic, as well as an antioxidant, antiallergenic, antimicrobial, antiviral, choleric, and antihypertensive agent. Therefore, the purpose of this study was to analyze the different extracts of H. italicum and to [...] Read more.

Helichrysum italicum (Roth) G. Don is widely used as a liver stimulant and diuretic, as well as an antioxidant, antiallergenic, antimicrobial, antiviral, choleric, and antihypertensive agent. Therefore, the purpose of this study was to analyze the different extracts of H. italicum and to determine the relationship between total phenolic/flavonoid content and antioxidant activity. Plant material was pulverized to be 0.3 and 2 mm, and the extraction was obtained with 5 mL of different ethanol concentrations (30, 40, 50, 60, 96%, v/v) and water during different periods (10, 30, 60 min and 24 h) and with concentrated methanol (95%, v/v), dichloromethane, acetone, chloroform, ethyl acetate, and hexane during 10 and 30 min due to solvents volatility. Extracts were evaporated on the rotary evaporator. Total phenolic and flavonoid content were determined via spectrophotometric measurement, and antioxidant capacity was investigated by the inhibitory activity of DPPH radicals. The group of 92 extracts described through their TPC, flavonoids, yield, and IC₅₀ values were subjected to PCA and HCA analysis. PCA and HCA were performed using Statistica v 10.0 software. The number of phenolic compounds ranged from 2.58 ± 0.1 to 43.60 ± 0.3 mg GAE/g of dry extract, and total flavonoids content ranged from 0.25 ± 0.01 to 23.96 ± 0.19 mg QE/g of dry extract. All extracts showed good antioxidant activity with an IC₅₀ value in the range from 4.92 ± 0.2 to 231.12 ± 1.9 μg/mL. PCA and HCA analysis were performed on the whole data set comprising 92 extracts for both particle sizes (s0.3 and s2) as well as heat map analysis. It was found that the increased time of extraction, concentration of ethanol, and degree of fragmentation enhances the quality of the extracts in terms of phenolic component content and antioxidant effects. Applied chemometric analysis contributed to the extraction conditions grouping, overview, and selection in order to distinguish the extracts with the promising TPC, flavonoids, yield, and IC₅₀ values. Full article

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

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13 pages, 3014 KiB

Open AccessArticle

Isolation of Osteoblastic Differentiation-Inducing Constituents from Peanut Sprouts and Development of Optimal Extraction Method

by Eun-Sang Cho, Chung Hyeon Lee, Min Sung Ko, Jee Yeon Choi, Kwang Woo Hwang and So-Young Park

Separations 2023, 10(8), 435; https://doi.org/10.3390/separations10080435 - 1 Aug 2023

Viewed by 1234

Abstract

Osteoporosis, one of the most common bone diseases, results from an imbalance between bone formation and resorption. Osteoblasts are primarily involved in bone formation, whereas osteoclasts are involved in bone resorption. Therefore, any substances that can increase osteoblastic differentiation would be beneficial for [...] Read more.

Osteoporosis, one of the most common bone diseases, results from an imbalance between bone formation and resorption. Osteoblasts are primarily involved in bone formation, whereas osteoclasts are involved in bone resorption. Therefore, any substances that can increase osteoblastic differentiation would be beneficial for the prevention or treatment of osteoporosis. In this study, peanut sprouts, a germinated product of peanuts, significantly enhanced osteoblastic differentiation of pre-osteoblastic MC3T3-E1 cells, as determined by the alkaline phosphatase (ALP) assay. The ethyl acetate fraction of peanut sprout extract was subjected to diverse column chromatographies using silica gel, ODS, and Sephadex LH-20 as stationary phases, and three nucleobases, namely, adenine, uracil, and thymine, and three phenolic acids, including caffeic acid, coumaric acid, and ferulic acid, were isolated as active constituents. In particular, adenine at 4 μg/mL and caffeic acid at 1 μg/mL increased ALP activity by 40 and 30%, respectively, compared with the osteoblastic differentiation medium-treated group, and these two compounds were set as marker compounds. Furthermore, extraction of peanut sprouts grown for 14–17 days with 60% ethanol was the best condition to obtain a high quantity of extract for peanut sprouts by analyzing the contents of marker compounds through HPLC. Together, these results suggest that peanut sprouts and their isolated compounds significantly enhance osteoblastic differentiation. Therefore, peanut sprouts have the potential to be developed as functional foods against osteoporosis. Full article

(This article belongs to the Special Issue Separation, Analysis and Biological Evaluation of Bioactive Compounds)

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13 pages, 2075 KiB

Open AccessArticle

Screening and Experimental Validation for Selection of Open Metal Sites Metal-Organic Framework (M-CPO-27, M = Co, Mg, Ni and Zn) to Capture CO₂

by Nor Ernie Fatriyah Kari, Marhaina Ismail, Aqeel Ahmad, Khaliesah Kamal, Thiam Leng Chew and Mohamad Azmi Bustam

Separations 2023, 10(8), 434; https://doi.org/10.3390/separations10080434 - 1 Aug 2023

Cited by 4 | Viewed by 1518

Abstract

The release of CO₂ into the atmosphere has become a primary issue nowadays. Recently, researchers found Metal-Organic Frameworks M-CPO-27 (M = Mg, Co, Ni, and Zn) to be revolutionary for CO₂ adsorption due to the presence of open metal sites enhancing [...] Read more.

The release of CO₂ into the atmosphere has become a primary issue nowadays. Recently, researchers found Metal-Organic Frameworks M-CPO-27 (M = Mg, Co, Ni, and Zn) to be revolutionary for CO₂ adsorption due to the presence of open metal sites enhancing CO₂ binding and leading to higher capacity. This study aims to select the best metal center for CPO-27 with the high performance of CO₂ adsorption by screening metal centers using simulation as a preliminary selection method. Then, the different metal centers were synthesized using the solvothermal process for validation. The synthesis of MOFs is confirmed through PXRD and FTIR analysis. Subsequently, by using simulation and experimental methods, it is discovered that Ni-CPO-27 gives the best performance compared with magnesium, zinc, and cobalt metal centers. The CO₂ adsorption capacity of synthesized Ni-CPO-27 is 5.6 mmol/g, which is almost 20% higher than other MOFs. In conclusion, the prospective outcome of changing the metal from Mg-CPO-27 to Ni-CPO-27 would be advantageous in this investigation owing to its excellent performance in capturing CO₂. Full article

(This article belongs to the Special Issue Advanced Techniques in the Separation Processes and Development of Novel Adsorbents)

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18 pages, 2220 KiB

Open AccessArticle

Water-Based Microwave-Assisted Extraction of Pigments from Madder Optimized by a Box–Behnken Design

by Marine Chambaud, Cyril Colas and Emilie Destandau

Separations 2023, 10(8), 433; https://doi.org/10.3390/separations10080433 - 30 Jul 2023

Cited by 1 | Viewed by 1514

Abstract

Water is one of the greenest and most accessible solvents. To harness its potential, the water-based microwave-assisted extraction (MAE) of pigments from madder was optimized by the response surface methodology (RSM) using a Box–Behnken experimental design. The extract that presented both the highest [...] Read more.

Water is one of the greenest and most accessible solvents. To harness its potential, the water-based microwave-assisted extraction (MAE) of pigments from madder was optimized by the response surface methodology (RSM) using a Box–Behnken experimental design. The extract that presented both the highest extraction yield and the most intense color was obtained after a 30-s cycle at 1000 W using 100 mg of madder for 20 mL of water. This water-based MAE was more efficient than Soxhlet extraction and proved comparable to hydroalcoholic MAE. The optimized extract was further characterized using UHPLC-HRMS/MS to identify its main compounds. Glycosylated flavonoids and anthraquinones were putatively identified, as well as free anthraquinones, generally found in madder. The microwave-assisted extraction extended the range of polarity of the extracted compounds, making the water more versatile. Full article

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

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16 pages, 4628 KiB

Open AccessArticle

Study of Estimated Ultimate Recovery Prediction and Multi-Stage Supercharging Technology for Shale Gas Wells

by Yanli Luo, Jianying Yang, Man Chen, Liu Yang, Hao Peng, Jinyuan Liang and Liming Zhang

Separations 2023, 10(8), 432; https://doi.org/10.3390/separations10080432 - 29 Jul 2023

Viewed by 1352

Abstract

The development of shale gas reservoirs often involves the utilization of horizontal well segmental multi-stage fracturing techniques. However, these reservoirs face challenges, such as rapid initial wellhead pressure and production decline, leading to extended periods of low-pressure production. To address these issues and [...] Read more.

The development of shale gas reservoirs often involves the utilization of horizontal well segmental multi-stage fracturing techniques. However, these reservoirs face challenges, such as rapid initial wellhead pressure and production decline, leading to extended periods of low-pressure production. To address these issues and enhance the production during the low-pressure stage, pressurized mining is considered as an effective measure. Determining the appropriate pressurization target and method for the shale gas wells is of great practical significance for ensuring stable production in shale gas fields. This study takes into account the current development status of shale gas fields and proposes a three-stage pressurization process. The process involves primary supercharging at the center station of the block, secondary supercharging at the gas collecting station, and the introduction of a small booster device located behind the platform separator and in front of the outbound valve group. By incorporating a compressor, the wellhead pressure can be reduced to 0.4 MPa, resulting in a daily output of 12,000 to 14,000 cubic meters from the platform. Using a critical liquid-carrying model for shale gas horizontal wells, this study demonstrates that reducing the wellhead pressure decreases the critical flow of liquid, thereby facilitating the discharge of the accumulated fluid from the gas well. Additionally, the formation pressure of shale gas wells is estimated using the mass balance method. This study calculates the cumulative production of different IPR curves based on the formation pressure. It develops a dynamic production decline model for gas outlet wells and establishes a relationship between the pressure depletion of gas reservoirs and the cumulative gas production before and after pressurization of H10 −2 and H10 −3 wells. The final estimated ultimate recovery of two wells is calculated. In conclusion, the implementation of multi-stage pressurization, as proposed in this study, effectively enhances the production of, and holds practical significance for, stable development of shale gas fields. Full article

(This article belongs to the Topic Oil, Gas and Water Separation Research)

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10 pages, 1515 KiB

Open AccessArticle

Separation of (2E,4E)-deca-2,4-dienal from a Biocatalytic Reaction Mixture Using Hydrophobic Adsorbents

by Marta Ostrihoňová, Monika Antošová, Hana Dobiašová, Justína Čuchorová, Kvetoslava Vranková and Milan Polakovič

Separations 2023, 10(8), 431; https://doi.org/10.3390/separations10080431 - 29 Jul 2023

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Abstract

Biocatalytic oxidation of a fatty acid preparation by enzymes released from a plant extract provided (2E,4E)-deca-2,4-dienal (2,4-DDAL), a valuable natural aroma. The post-reaction mixture contained several other compounds, from which 2,4-DDAL must be recovered. These included the main by-product trans-2-hexenal (2-HAL) and the [...] Read more.

Biocatalytic oxidation of a fatty acid preparation by enzymes released from a plant extract provided (2E,4E)-deca-2,4-dienal (2,4-DDAL), a valuable natural aroma. The post-reaction mixture contained several other compounds, from which 2,4-DDAL must be recovered. These included the main by-product trans-2-hexenal (2-HAL) and the unreacted substrate composed mainly of linoleic, palmitic, and oleic acids. The adsorption capacity and selectivity of 17 hydrophobic adsorbents were examined in batch equilibrium experiments. The highest binding capacity for 2,4-DDAL was around 30 mg/g. Due to a large excess of fatty acids in the mixture, the total adsorbed amounts of other components analyzed reached the values up to 150 mg/g. In addition, 2-HAL was always adsorbed more strongly than 2,4-DDAL, whereas fatty acids were mostly not adsorbed as effectively. The best-performing adsorbent, AmberLite FPX66, had a selectivity ratio of 6 for 2,4-DDAL with respect to the key impurity and linoleic acid. Ethanol, isopropanol, and acetone were examined as potential desorbents using batch adsorption experiments on AmberLite FPX66 from 2,4-DDAL solutions in organic solvents. Ethanol was found to be the best choice. Based on the batch equilibrium data, a column elution experiment was performed to purify 2,4-DDAL from the biocatalytic reaction mixture using elution with 96% ethanol. Full article

(This article belongs to the Collection Feature Paper Collection in Section 'Purification Technology')

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Separations, Volume 10, Issue 8 (August 2023) – 42 articles

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