Separations

Open AccessArticle

Phytochemistry and Biological Activities of Essential Oils from Satureja calamintha Nepeta

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Rajae El Brahimi

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Azeddin El Barnossi

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Abdelfattah El Moussaoui

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Ahmad Mohammad Salamatullah

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Mohammed Bourhia

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Amina Bari

Separations 2023, 10(6), 344; https://doi.org/10.3390/separations10060344 - 05 Jun 2023

Abstract

Satureja calamintha nepeta (S. calamintha) has a history of successful use in the treatment of bacterial and fungal diseases. The present study was designed to investigate the chemical composition and antioxidant and antimicrobial activities of essential oils extracted from wild S. [...] Read more.

Satureja calamintha nepeta (S. calamintha) has a history of successful use in the treatment of bacterial and fungal diseases. The present study was designed to investigate the chemical composition and antioxidant and antimicrobial activities of essential oils extracted from wild S. calamintha (EOSS) and domesticated S. calamintha (EOSD) for comparison purposes. Hydrodistillation was used to extract the essential oils (EOs), while GC/MS was used for chemical analysis. Antioxidant activity was studied using DPPH and FRAP assays. Antifungal activity was performed against Candida albicans, Aspergillus niger, Aspergillus flavus, and Fusarium oxysporum), while antibacterial activity was tested against clinically resistant bacteria, namely Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Proteus mirabilis. By using ab=n in silico approach, the antioxidant and antimicrobial activities of the main compounds of EOSS and EOSD were also investigated. The yields obtained of EOSS and EOSD were 2.80% and 1.95%, respectively, with a dominance of eucalyptol, pulegone and rotundifolone. Concerning the antioxidant power, the IC50 values recorded by the use of the DPPH assay were in the range of 23.03 ± 4.30 and 24.09 ± 4.38 μg/mL for EOSS and EOSD, respectively, while by using the FRAP assay, the EC₅₀ values were in the range of 55.38 ± 2.16 and 60.72 ± 7.71 μg/mL for EOSS and EOSD, respectively. Importantly, both essential oils of EOSS and EOSD exhibited good antibacterial activity against all studied bacteria; notably, the inhibition zone ranged from 14 ± 0.00 to 48.67 ± 1.15 mm and the MICs ranged from 0.37 ± 0.00 to 5.96 ± 0.00 µg/mL. Similarly, the studied EOs showed important antifungal activities compared to all the studied fungi, wherein the inhibition percentage ranged from 47.33 ± 1.15 to 89.18 ± 0.75%, while the MICs ranged from 0.18 ± 0.00 to 2.98 ± 0.00 µg/mL. The molecular docking results showed that piperitenone and pulegone strongly inhibited human acetylcholinesterase, whereas (+)-Isomenthone and piperitenone strongly inhibited S. aureus nucleoside diphosphate kinase, and E. coli beta-ketoacyl-[acyl carrier protein] synthase, respectively. The outcome of this article suggests that EOs of S. calamintha can be developed as alternative agents to manage drug-resistant phenomena and free radical issues. Full article

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

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Open AccessArticle

Development and Validation of UPLC–MS/MS Method for Quantitative Analysis of 5-Fluorouracil in Aqueous Humor of Rabbits

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Mohd Abul Kalam

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Sulaiman S. Alhudaithi

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Adel Ali Alhowyan

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Muzaffar Iqbal

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Mohammad Raish

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Abdullah K. Alshememry

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Musaed Alkholief

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Aliyah A. Almomen

and

Aws Alshamsan

Separations 2023, 10(6), 343; https://doi.org/10.3390/separations10060343 - 02 Jun 2023

Abstract

5-Fluorouracil (5-FU) is now used in eye drops for the management of conjunctival malignant melanoma, intraepithelial neoplasia, and corneal and conjunctival squamous cell carcinoma. The previously used methods for 5-FU quantification in AqH were time-consuming and less sensitive. Herein, a highly perceptive bioanalytical [...] Read more.

5-Fluorouracil (5-FU) is now used in eye drops for the management of conjunctival malignant melanoma, intraepithelial neoplasia, and corneal and conjunctival squamous cell carcinoma. The previously used methods for 5-FU quantification in AqH were time-consuming and less sensitive. Herein, a highly perceptive bioanalytical UPLC–MS/MS method was developed for the quantitative determination of 5-FU in the aqueous humor (AqH) of rabbits using allopurinol as the internal standard (IS). The 5-FU and IS were well separated in an Acquity™ HILIC column. Acetonitrile and 10 mM of ammonium acetate at 95:5 (v/v) were isocratically pumped at a 0.3 mL/min flow rate with a total runtime of 2.5 min. AqH samples were processed with a liquid–liquid extraction method in ethyl acetate. The 5-FU and IS were identified in the negative mode with electrospray ionization. The parent to daughter ion transitions for the 5-FU and IS occurred at m/z 128.92→41.68 and 134.80→64.10, respectively, as quantified using the multiple reaction monitoring mode. The developed method was validated with the ICH-Harmonized Guideline for Bioanalytical Method Validation, and the parameters were within acceptable limits. The calibration curve was linear at the 10.5–2000 ng/mL concentration range, with a correlation coefficient (R²) of 0.9946, and the lower limit of detection was 3.55 ng/mL. The developed and validated method was rapid, sensitive, accurate and robustly able to quantify 5-FU in rabbit AqH. The method was effectively applied to establish the ocular pharmacokinetics of 5-FU following the topical instillation of 5-FU-containing preparations in rabbits. Full article

(This article belongs to the Special Issue Application of Chromatography in Pharmaceutical and Biomedical Analysis)

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Open AccessArticle

Experimental Design Approach for Development of HPLC Method for Simultaneous Analysis of Triamcinolone, Nystatin, and Gramicidin in Industrial Wastewater

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Separations 2023, 10(6), 342; https://doi.org/10.3390/separations10060342 - 01 Jun 2023

Abstract

This study used an experimental design approach to optimize an HPLC method for the simultaneous determination of three pharmaceutical residues (triamcinolone, nystatin, and gramicidin) in industrial wastewater samples. The goal of using an experimental design approach was to maximize the method performance through [...] Read more.

This study used an experimental design approach to optimize an HPLC method for the simultaneous determination of three pharmaceutical residues (triamcinolone, nystatin, and gramicidin) in industrial wastewater samples. The goal of using an experimental design approach was to maximize the method performance through separation enhancement and shortening the time of analysis and/or minimizing the environmental effects through the reduction in wastes and sample treatment. To achieve this goal, two steps were performed: a full factorial screening design for the three chromatographic variables, and optimization design using central composite design to select the optimum conditions that accomplished the highest resolution between adjacent peaks within a minimum run time of less than 5 min. The optimal chromatographic conditions derived from Minitab software using the desirability function were applied. Separation was carried out on a Zorbax C18 column (250 mm × 4.6, 5 μm) with gradient elution of a mobile phase composed of methanol and 0.25 M potassium dihydrogen phosphate buffer (pH 3.6) at different UV detections. For the validation of the developed HPLC method, ICH guidelines were followed, and the obtained results were found to be in compliance with the acceptance criteria. Linearity was over the concentration range of 1.00–25.00 μg/mL for triamcinilone and nystatin and 10.00–50.00 µg/mL for gramicidin. The proposed method was successfully applied to quantify the three studied pharmaceutical compounds in rinsing wastewater samples. Full article

(This article belongs to the Special Issue Sensitivity Enhancement Approaches to the Separation Techniques for Pharmaceutical Analysis and Therapeutic Drug Monitoring)

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Open AccessArticle

Extractive Distillation Approach to the Separation of Styrene from Pyrolysis Gasoline Feedstock Coupled with Deep Desulfurization

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Separations 2023, 10(6), 341; https://doi.org/10.3390/separations10060341 - 01 Jun 2023

Abstract

The separation of mixtures with close boiling points is a critical task in the petrochemical industry, and one such mixture that requires separation is o-xylene/styrene. The STED process is used to separate o-xylene/styrene, which contains a certain amount of organic sulfur in the [...] Read more.

The separation of mixtures with close boiling points is a critical task in the petrochemical industry, and one such mixture that requires separation is o-xylene/styrene. The STED process is used to separate o-xylene/styrene, which contains a certain amount of organic sulfur in the product due to the limitations of the process. In this study, the process underwent enhancements to attain the effective separation of styrene and accomplish deep desulfurization. A mixture of sulfolane (SUL) and N-methylpyrrolidone (NMP) was selected as the extraction solvent after calculating the UNIFAC group contributions. An orthogonal experiment was conducted to investigate the effects of the solvent/oil ratio, reflux ratio, water addition rate, and solvent ratio on the product. The correspondence between each factor and the indexes examined was determined, enabling the optimization and prediction of the styrene product quality. The final optimized conditions for the extractive distillation column are as follows: solvent/oil ratio of 7, reflux ratio of 4.5, water addition rate of 6000 kg/h, and a solvent ratio of 9:1. Under optimal conditions, the purity of the product was observed to be greater than that of the original process and the sulfur content of the product can be reduced to lower than 10 ppm at the cost of an increase of 12.31% in energy consumption. Full article

(This article belongs to the Special Issue Recent Advances in Purification and Separation of Oil and Gas Resources)

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Open AccessArticle

Identification and Assessment of Therapeutic Phytoconstituents of Catharanthus roseus through GC-MS Analysis

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Separations 2023, 10(6), 340; https://doi.org/10.3390/separations10060340 - 01 Jun 2023

Abstract

The leaves of Catharanthus roseus (L.) G. Don contain a large number of diverse secondary metabolites, making them comparably complex. The Catharanthus genus has received increased interest from scientists in recent years due to its extensive applications in several domains, including the pharmaceutical [...] Read more.

The leaves of Catharanthus roseus (L.) G. Don contain a large number of diverse secondary metabolites, making them comparably complex. The Catharanthus genus has received increased interest from scientists in recent years due to its extensive applications in several domains, including the pharmaceutical sector, where precise characterization of its characteristics is required. An effective inquiry technique is needed for chemo-profiling to identify the metabolites in plant samples. The main goal of this research is to provide supplementary data on the chemical composition of the leaves of twenty-five different accessions of C. roseus through the application of gas chromatography-mass spectrometry (GC-MS). The study’s findings reveal the existence of a vast number of phytochemicals, allowing for a comparison of the different accessions. Furthermore, a meticulous statistical analysis of this data using principal components analysis (PCA) and a heatmap, and hierarchical cluster analysis (HCA) may aid in providing more relevant information on C. roseus leaves for possible investigation of their metabolites in further scientific studies. Full article

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Open AccessArticle

Application of ZnO/WO₃ Composite Nanofiber Photocatalysts in Textile Wastewater Treatment

by

Yongxin Xu

,

Hui Yan

and

Tiwei Chen

Separations 2023, 10(6), 339; https://doi.org/10.3390/separations10060339 - 31 May 2023

Abstract

Semiconductor photocatalysis technology is an environmentally friendly and efficient emerging technology. This method can use sunlight as a driving force to quickly decompose organic pollutants in water bodies. Zinc oxide (ZnO) and tungsten oxide (WO₃) photocatalysts can absorb sunlight and participate [...] Read more.

Semiconductor photocatalysis technology is an environmentally friendly and efficient emerging technology. This method can use sunlight as a driving force to quickly decompose organic pollutants in water bodies. Zinc oxide (ZnO) and tungsten oxide (WO₃) photocatalysts can absorb sunlight and participate in photocatalytic degradation reactions due to their relatively narrow band gap. Highly photosensitive WO₃ nanofibers and ZnO/WO₃ composite nanofibers were fabricated via the electrospinning method. When 100 mg/L of rhodamine B (Rh B) solution was used as the degradation substrate, the degradation efficiencies of WO₃ and ZnO/WO₃ for Rh B dye were 70% and 90%, respectively, after a photocatalytic reaction of 120 min. The surface morphology, crystal structure, and optical properties of ZnO/WO₃ composite nanofibers and WO₃ nanofibers were characterized by SEM, XRD, XPS, and UV-vis absorption spectra, and the experimental results were analyzed and explained using different mechanisms. The results show that ZnO/WO₃ composite nanofibers have better UV-visible light absorption performance, and the sample has a higher UV-visible light utilization rate. This was mainly due to the fact that a P-N heterojunction was formed in the semiconductor composite, and the electron–hole pair could realize rapid separation under the drive of a built-in electric field force, which promoted the migration of carrier. Therefore, the photocatalytic activity of the ZnO/WO₃ catalyst was significantly higher than that of the WO₃ catalyst, which promoted rapid improvement of the photocatalytic degradation efficiency of the Rh B dye. Full article

(This article belongs to the Special Issue Application of Nanotechnology and Nanomaterials in Removal of Heavy Metals, Dyes, or Emerging Pollutants from Wastewater)

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Open AccessArticle

Identification and Quantification of Polyphenolic Secondary Metabolites in Stem Bark of Ficus religiosa (Moraceae) Using UPLC-HRMS and RP-HPLC-PDA

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Separations 2023, 10(6), 338; https://doi.org/10.3390/separations10060338 - 31 May 2023

Abstract

F. religiosa bark has been extensively used in traditional medicinal systems, such as Ayurveda, for its health benefits. The aim of this study was to investigate the secondary metabolites (phenolics and flavonoids) of the hydroalcoholic stem-bark extract from F. religiosa because this plant [...] Read more.

F. religiosa bark has been extensively used in traditional medicinal systems, such as Ayurveda, for its health benefits. The aim of this study was to investigate the secondary metabolites (phenolics and flavonoids) of the hydroalcoholic stem-bark extract from F. religiosa because this plant has been proven to have a beneficial effect on health disorders. Therefore, a pilot study was conducted for the identification and quantification of polyphenolic compounds in F. religiosa bark using sophisticated chromatographical techniques such as UPLC-HRMS and RP-HPLC-PDA. Additionally, total flavonoids, total phenolics and the scavenging profile of the bark were studied using a UV spectrophotometer. A total of 23 compounds identified with UPLC-HRMS were mainly phenolic acids, polyphenolics, and flavonoids (flavanols and proanthocyanidins). Among the identified compounds, gallic acid, catechin, epicatechin, epigallocatechin gallate, and ellagic acid were simultaneously quantified (0.031–0.380%) using RP-HPLC-PDA. Thereafter, the study complied by evaluating the total flavonoids (109.15 ± 1.2 mg RuE/g and 33.78 ± 0.86 mg CaE/g), total phenolics (4.81 ± 1.01 mg GaE/g), and scavenging profiles (IC₅₀ 13.75 ± 0.12 µg/mL) of the F. religiosa bark. This is the first report on the chemical profiling of F. religiosa bark, which is a necessary step to evaluate its nutraceutical properties, paving the way for possible food application. Full article

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

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Open AccessReview

A Comprehensive Review of the Developments in Electrocoagulation for the Removal of Contaminants from Wastewater

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Separations 2023, 10(6), 337; https://doi.org/10.3390/separations10060337 - 30 May 2023

Abstract

Water organic pollution has become a major issue. A large number of people suffer from the decline in water quality. In addition, polluted water can lead to health problems or excessive deaths. In this regard, an increasingly important method for efficient water treatment [...] Read more.

Water organic pollution has become a major issue. A large number of people suffer from the decline in water quality. In addition, polluted water can lead to health problems or excessive deaths. In this regard, an increasingly important method for efficient water treatment is electrocoagulation (EC), the technology that encompasses a small equipment size combined with a simple operation compared to other water treatment methods. The importance of EC is especially accentuated by the recent decarbonization efforts due to the increasing availability of renewable electricity systems. This review provides an overview of the most recent developments in EC technology as it pertains to wastewater treatment. The EC is preferred for organic wastewater treatment over other traditional treatment methods due to its easy setup and low material costs. Moreover, the EC is very powerful in destabilizing organic impurities by charge neutralization and then coagulating to form flocs. In addition, EC has shown high efficiency not only in removing various organic pollutants but also in emerging persistent contaminants, such as microplastics. For these reasons, the EC mechanisms and related functional modalities are reviewed, as well as extensive details are provided on the diversity of the removed contaminants. Overall, this review provides significant new knowledge of interest for environmental chemical researchers in particular and engineers in general on the details of the EC technology for wastewater treatment and water purification. Full article

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

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Open AccessArticle

Exploration of Large-Scale Application of Efficient and Clean Utilization of Low-Grade Bauxite

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Separations 2023, 10(6), 336; https://doi.org/10.3390/separations10060336 - 30 May 2023

Abstract

In recent years, the rapid development of the domestic alumina industry has greatly accelerated the consumption of high-alumina–silica-ratio bauxite resources in China. The development of an efficient and clean utilization technology applicable to low-grade bauxite in China is not only a requirement for [...] Read more.

In recent years, the rapid development of the domestic alumina industry has greatly accelerated the consumption of high-alumina–silica-ratio bauxite resources in China. The development of an efficient and clean utilization technology applicable to low-grade bauxite in China is not only a requirement for resource and environmental protection, but also a powerful guarantee to maintain the sustainable development of China’s aluminum industry. Based on this, the authors’ team proposed a new process for the treatment of low-grade bauxite ore via a calcification–carbonization method from the perspective of equilibrium solid-phase reconstruction and achieved the first industrial-scale trial run on the basis of existing laboratory research. The results show that the mass fraction of Na₂O in bauxite residue can be reduced to 0.95% in the treatment of typical diaspore bauxite, the A/S in the bauxite residue can be reduced to 0.85 after two-time carbonization–alumina dissolution, and the actual alumina dissolution rate can reach 81.32%. The relevant results verified the feasibility and advantages of the calcification–carbonization method in industrial production. Full article

(This article belongs to the Special Issue Efficient and Green Recovery of Metal Minerals)

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Open AccessCommunication

Triplet-Excited Dissolved Organic Matter Efficiently Promoted Atmospheric Sulfate Production: Kinetics and Mechanisms

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Separations 2023, 10(6), 335; https://doi.org/10.3390/separations10060335 - 30 May 2023

Abstract

Photochemical generation is an important pathway for atmospheric sulfate formation. However, the roles of atmospheric co-existing photosensitive dissolved organic matter (DOM) in sulfate formation are still unclear. The experimental results in this work provide evidence that atmospheric photosensitizers produce active intermediates to oxidize [...] Read more.

Photochemical generation is an important pathway for atmospheric sulfate formation. However, the roles of atmospheric co-existing photosensitive dissolved organic matter (DOM) in sulfate formation are still unclear. The experimental results in this work provide evidence that atmospheric photosensitizers produce active intermediates to oxidize S(IV) into S(VI) under illumination. Quenching experiments of eight photosensitive model compounds (PS) demonstrate that their triplet-excited states (³PS*) dominate sulfate formation for the photosensitizing pathway with a contribution of over 90%, and ¹O₂ plays an important role in sulfate formation. The results using humic acid (HA) and water-soluble organic carbon in vehicle exhaust particles (WSOC) as representatives of atmospheric photosensitizers further verify that triplet-excited DOM (³DOM*) is the main reactive species for sulfate formation, which is consistent with the results of PS. Our findings provide new insights into the photochemical formation pathways of atmospheric sulfate. Full article

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

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Open AccessArticle

Multivariate Simultaneous Determination of Some PAHs in Persian Gulf Oil-Contaminated Algae and Water Samples Using Miniaturized Triton X-100-Mediated Fe₃O₄ Nanoadsorbent and UV-Vis Detection

by

Maryam Abbasi Tarighat

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Ameneh Behroozi

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Gholamreza Abdi

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Charalampos Proestos

Separations 2023, 10(6), 334; https://doi.org/10.3390/separations10060334 - 29 May 2023

Abstract

This research shows the development of a miniaturized solid-phase extraction method with UV-Vis detection for simultaneous determination of dibenzofuran, fluoranthene and phenanthrene using chemometrics approaches. After synthesis of Fe₃O₄ nanoparticles (Fe₃O₄ NPs), the surface of the nanoparticles [...] Read more.

This research shows the development of a miniaturized solid-phase extraction method with UV-Vis detection for simultaneous determination of dibenzofuran, fluoranthene and phenanthrene using chemometrics approaches. After synthesis of Fe₃O₄ nanoparticles (Fe₃O₄ NPs), the surface of the nanoparticles was modified by Triton X100 coating. The influence of extraction solvent and volume, concentration of Triton X100, extraction time, and sample pH were studied and optimized. Due to high spectral overlapping, resolving ternary mixtures for simultaneous determination of targets with classical analytical methods is impossible. Therefore, the recorded UV-Vis spectra were transformed using continuous wavelet transform and then subjected to artificial neural networks (ANNs). The Db4 mother wavelet was used as the better mother wavelet. For simultaneous detection of analytes, a comparison of feed-forward back-propagation and radial basis function networks was accomplished. The calibration graphs showed linearity in the ranges of 2.4–250 ng mL⁻¹, 50–3750 ng mL⁻¹, and 48–5000 ng mL⁻¹ with a limit of detection of 0.58, 9.5 ng mL⁻¹, and 12.5 ng mL⁻¹ under optimal conditions for phenanthrene, fluoranthene, and dibenzofuran, respectively. The limit of quantitation was achieved at 3.52 ng mL⁻¹, 16.35 ng mL⁻¹, and 31.3 ng mL⁻¹ for phenanthrene, fluoranthene and dibenzofuran, respectively. The method involving TX-100-coated Fe₃O₄ NPs in a liquid sample phase for analyte extraction, followed by ethanol desorption and UV-Vis detection, was successfully applied for the determination of polycyclic aromatic hydrocarbons in oil-field water and algae samples. Full article

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

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Open AccessReview

Strategies for Natural Product Discovery by Unlocking Cryptic Biosynthetic Gene Clusters in Fungi

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Separations 2023, 10(6), 333; https://doi.org/10.3390/separations10060333 - 26 May 2023

Abstract

Recent advancements in genome sequencing and bioinformatic analysis of fungal genomes have revealed that fungi possess cryptic or silent biosynthetic gene clusters (BGCs). This discovery suggests that our understanding of the universe of fungal secondary metabolomes is limited. In this review, we summarize [...] Read more.

Recent advancements in genome sequencing and bioinformatic analysis of fungal genomes have revealed that fungi possess cryptic or silent biosynthetic gene clusters (BGCs). This discovery suggests that our understanding of the universe of fungal secondary metabolomes is limited. In this review, we summarize recent strategies for activating cryptic BGCs in fungi, identify fungal secondary metabolites, and highlight their biological activities. We also briefly discuss the isolation and purification methods for these compounds. Our focus is on genetics-dependent and genetics-independent approaches for activating cryptic BGCs in fungi. Using the strategies discussed here, cryptic fungal natural products hold significant potential as a source for the discovery of new drug candidates. Full article

(This article belongs to the Special Issue Extraction, Purification and Structure Elucidation of Active Natural Compounds)

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Open AccessArticle

Exploring the Chemical Composition and Antioxidant Properties of Apricot Kernel Oil

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Ioannis Makrygiannis

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Vassilis Athanasiadis

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Theodoros Chatzimitakos

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Eleni Bozinou

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Christiana Mantzourani

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Arhontoula Chatzilazarou

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Dimitris P. Makris

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Stavros I. Lalas

Separations 2023, 10(6), 332; https://doi.org/10.3390/separations10060332 - 26 May 2023

Abstract

Apricot kernels are known to be rich in bioactive compounds such as polyphenols, which have applications in various fields such as cosmetology and the food industry. However, the extraction of these compounds has not been extensively studied. In this study, we aimed to [...] Read more.

Apricot kernels are known to be rich in bioactive compounds such as polyphenols, which have applications in various fields such as cosmetology and the food industry. However, the extraction of these compounds has not been extensively studied. In this study, we aimed to extract oil from apricot kernels and investigate its composition and antioxidant properties. Samples from two years of apricot cannery by-products were used in the study. We employed a common extraction procedure using hexane as a solvent, followed by an analysis of the oil’s fatty acid composition and determination of its antioxidant properties using several methods. Our results indicated that the oil extracted from apricot kernels is rich in oleic and palmitoleic acids, which exhibit health benefits. As regards the volatile compounds of the oil, 2-methyl propanal, benzaldehyde, and benzyl alcohol were detected as the main compounds. Benzaldehyde was also found to be the main component of the essential oil of the kernel. Furthermore, the oil exhibited low antioxidant activity, as demonstrated by its ability to scavenge free radicals. Overall, our findings suggest that apricot kernels are a valuable source of oil with potential applications in the food and cosmetic industries. Full article

(This article belongs to the Special Issue Application of Separation Technology in Chemistry)

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Open AccessFeature PaperArticle

Effect of Scale-Up on Residence Time and Uranium Extraction on Annular Centrifugal Contactors (ACCs)

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Separations 2023, 10(6), 331; https://doi.org/10.3390/separations10060331 - 26 May 2023

Abstract

This work reports the effect of scaling up annular centrifugal contactors (ACCs) upon the residence time distribution and the efficiency of extraction of uranium. The experiments were carried out in a multi-scale ACC platform of three ACCs with rotor diameters of 12, 25, [...] Read more.

This work reports the effect of scaling up annular centrifugal contactors (ACCs) upon the residence time distribution and the efficiency of extraction of uranium. The experiments were carried out in a multi-scale ACC platform of three ACCs with rotor diameters of 12, 25, and 40 mm. To enable direct comparison across all three scales of ACC, the residence time distributions were acquired by injecting dye into the solvent phase at a constant relative volume related to the ACC liquid holdup. Across all scales and flowrates, there was little difference in residence time distribution (<6 residence volumes), except for the smallest 12 mm rotor diameter ACC with a high solvent/aqueous feed ratio, which required 12 residence volumes, potentially due to internal circulation in the annulus. At low flowrates, the stage efficiency in all cases was >95%, and it improved further in larger rotor diameter ACCs. Full article

(This article belongs to the Special Issue Advanced Methods for Separation and Extraction of Radionuclides)

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Open AccessArticle

An LC–MS/MS Analytical Method for Quantifying Tepotinib in Human Liver Microsomes: Application to In Vitro and In Silico Metabolic Stability Estimation

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Separations 2023, 10(6), 330; https://doi.org/10.3390/separations10060330 - 26 May 2023

Abstract

Tepotinib (MSC2156119) is a potent mesenchymal–epithelial transition (MET) factor inhibitor, a receptor tyrosine kinase that plays a crucial role in promoting cancer cell malignant progression. Adverse effects of tepotinib (TEP), such as peripheral edema, interstitial lung disease, nausea and diarrhea, occur due to [...] Read more.

Tepotinib (MSC2156119) is a potent mesenchymal–epithelial transition (MET) factor inhibitor, a receptor tyrosine kinase that plays a crucial role in promoting cancer cell malignant progression. Adverse effects of tepotinib (TEP), such as peripheral edema, interstitial lung disease, nausea and diarrhea, occur due to drug accumulation and lead to termination of therapy. Therefore, the in silico and experimental metabolic susceptibility of TEP was investigated. In the current work, an LC-MS/MS analytical method was developed for TEP estimation with metabolic stability assessment. TEP and lapatinib (LTP) used as internal standards (ISs) were separated on a reversed-phase C18 column using the isocratic mobile phase. Protein precipitation steps were used to extract TEP from the human liver microsome (HLM) matrix. An electrospray ionization multi-reaction monitoring (MRM) acquisition was conducted at m/z 493→112 for TEP, at m/z 581→350, and 581→365 for the IS. Calibration was in the range of 5 to 500 ng/mL (R² = 0.999). The limit of detection (LOD) was 0.4759 ng/mL, whereas the limit of quantification (LOQ) was 1.4421 ng/mL. The reproducibility of the developed analytical method (inter- and intra-day precision and accuracy) was within 4.39%. The metabolic stability of TEP in HLM was successfully assessed using the LC-MS/MS method. The metabolic stability assessment of TEP showed intermediate Cl_int (35.79 mL/min/kg) and a moderate in vitro t_1/2 (22.65 min), proposing the good bioavailability and moderate extraction ratio of TEP. The in silico results revealed that the N-methyl piperidine group is the main reason of TEP metabolic lability. The in silico Star Drop software program could be used in an effective protocol to confirm and propose the practical in vitro metabolic experiments to spare resources and time, especially during the first stages for designing new drugs. The established analytical method is considered the first LC-MS/MS method for TEP estimation in the HLM matrix with its application to metabolic stability assessment. Full article

(This article belongs to the Special Issue Application of Liquid Chromatography in Pharmaceutical and Toxicological Analysis)

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Open AccessArticle

Promising Insecticidal Properties of Essential Oils from Artemisia aragonensis Lam. and Artemisia negrei L. (Asteraceae) by Targeting Gamma-Aminobutyric Acid and Ryanodine Receptor Proteins: In Vitro and In Silico Approaches

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Khalid Chebbac

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Zineb Benziane Ouaritini

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Abdelfattah El Moussaoui

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Separations 2023, 10(6), 329; https://doi.org/10.3390/separations10060329 - 26 May 2023

Abstract

Artemisia negrei (A. negrei) and Artemisia aragonensis (A. aragonensis) are in the family Asteraceae, which has been used in traditional medicine. The use of plant-derived insecticides has become a promising strategy to reduce the harmful effects of synthetic insecticides [...] Read more.

Artemisia negrei (A. negrei) and Artemisia aragonensis (A. aragonensis) are in the family Asteraceae, which has been used in traditional medicine. The use of plant-derived insecticides has become a promising strategy to reduce the harmful effects of synthetic insecticides and overcome the bio-resistance of pest insects to insecticides. In this regard, the purpose of the current study was to determine the chemical composition and evaluate insecticidal effects of essential oils (EOs) extracted from A. negrei (EON) and A. aragonensis (EOA). Notably, all chemical constituents present in the EOs were identified through GC-MS analysis, whilst the insecticidal properties against Callosobruchus maculatus Fab. (C. maculatus) were investigated by use of in vitro an in silico approaches. The obtained results showed that both tested EOs present a significant insecticidal effect against C. maculatus, which increased significantly upon the dose used in both contact and inhalation tests. The lethal concentrations (LC₅₀) for the inhalation test were found to be 2.1 and 2.97 μL/L, while in the contact test they were 2.08 and 2.74 μL/L of air for EON and EOA, respectively. At 5 μL/L of air, the spawn reduction rate was 88.53 % and 77.41%, while the emergence reduction rate was 94.86% and 81.22% by EON and EOA, respectively. With increasing doses of up to 20 μL/L of air, the reduction in individual emergence reached 100% by the two oils tested after 36 h of treatment. In addition, Molecular docking (MD) simulations supported the in vitro findings and indicated that certain identified components in EOA and EON exhibited stronger hydrogen bonding interactions with the target receptors. Interestingly, the prediction of ADMET properties indicates that the molecules investigated have great pharmacokinetic profiles with no side effects. Taken together, our findings suggest that EOA and EON may exert both potential contact and inhalation insecticidal actions and could be used as an alternative tool for the control of this major insect pest of stored products. Full article

(This article belongs to the Special Issue Essential Oils: Extraction, Chemical Composition, and Biological Activity)

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Open AccessArticle

Service Life Prediction of Concrete Coated with Surface Protection Materials by Ultrasonic Velocity in Cold Region

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Separations 2023, 10(6), 328; https://doi.org/10.3390/separations10060328 - 25 May 2023

Abstract

Lithium silicate (LS) crack repairing material, working as a crystal waterproof material, could be used to strengthen concrete made from solid waste materials. This paper presents the results of water absorption and rapid freeze–thaw tests with concrete specimens coated with LS. Concrete specimens [...] Read more.

Lithium silicate (LS) crack repairing material, working as a crystal waterproof material, could be used to strengthen concrete made from solid waste materials. This paper presents the results of water absorption and rapid freeze–thaw tests with concrete specimens coated with LS. Concrete specimens with different water–binder ratios and air content (0.35–1 and 0.55–4.5) were tested. The moisture uptake and water absorption coefficient were analyzed in the water absorption test. The water absorption coefficient of LS-coated specimens was lower than that of uncoated specimens, resulting in a lower total moisture content. The relative dynamic modulus of elasticity was calculated by the fundamental transverse frequency (Er) and ultrasonic velocity (Ev), respectively. Er and Ev exhibited similar attenuation characteristics, and the attenuation of LS-coated specimens was lower than that of uncoated specimens. A two-segment freeze–thaw damage model based on Er and Ev was employed to predict the service life of concrete. The relative errors of the service life results calculated by Er and Ev were within 10%. The two-segment freeze–thaw model could be used for the service life prediction of concrete structures. The present work provides new insight into using LS to improve the service life of concrete. Full article

(This article belongs to the Special Issue Advances in Solid Waste Separation/Treatment and Its Utilization in Building Materials)

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Open AccessEditorial

Is Chromatographic Efficiency Possible Using Molecularly Imprinted Stationary Phases?

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W. Rudolf Seitz

Separations 2023, 10(6), 327; https://doi.org/10.3390/separations10060327 - 25 May 2023

Abstract

Molecularly imprinted polymers are prepared in the presence of a template. They have been shown to resolve enantiomers when used as stationary phases for liquid chromatography. However, the separation efficiency is not as good as that observed with silica stationary phases. This manuscript [...] Read more.

Molecularly imprinted polymers are prepared in the presence of a template. They have been shown to resolve enantiomers when used as stationary phases for liquid chromatography. However, the separation efficiency is not as good as that observed with silica stationary phases. This manuscript identifies the main problems as the slow transfer kinetics between the mobile and stationary phase and the heterogeneity of the stationary phase binding sites. It suggests that preparing templated polymers that have predominantly or exclusively noncovalent crosslinks is the most promising approach for improving efficiency. Full article

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

Open AccessArticle

Impact and Optimization of the Conditions of Extraction of Phenolic Compounds and Antioxidant Activity of Olive Leaves (Moroccan picholine) Using Response Surface Methodology

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El Mustapha El Adnany

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Separations 2023, 10(6), 326; https://doi.org/10.3390/separations10060326 - 25 May 2023

Abstract

The Moroccan picholine tree’s leaves contain phenolic compounds that benefit human health. However, the amount and type of these compounds can vary based on factors such as the extraction method and conditions. This study aimed to improve phenolic compounds’ extraction while minimising harmful [...] Read more.

The Moroccan picholine tree’s leaves contain phenolic compounds that benefit human health. However, the amount and type of these compounds can vary based on factors such as the extraction method and conditions. This study aimed to improve phenolic compounds’ extraction while minimising harmful chemicals’ use. It has been found that using ethanol as a solvent with ultrasonic extraction is the most effective and environmentally friendly technique. Several parameters, such as the extraction time, solid/solvent ratio, and ethanol concentration as independent variables, were evaluated using a surface response method (RSM) based on the Box–Behnken design (BBD) to optimize the extraction conditions. The experimental data were fitted to a second-order polynomial equation using multiple regression analysis and also examined using the appropriate statistical methods. In optimal conditions, the ultrasonic time, the ratio (solvent/solid) and the concentration (ethanol/water), the content of total polyphenols (TPC), total flavonoids (TFC), and antioxidant activity (by DPPH, ABTS, FRAP) were, respectively, 74.45 ± 1.22 mg EAG/g DM, 17.08 ± 1.85 mg EC/g DM, 83.45 ± 0.89% 82.85 ± 1.52%, and 85.01 ± 2.35%. The identification of phenolic compounds by chromatography coupled with mass spectrum (HPLC-MS) under optimal conditions with two successive extractions showed the presence of hydroxytyrosol, catechin, caffeic acid, vanillin, naringin, oleuropein, quercetin, and kaempferol at high concentrations. Full article

(This article belongs to the Special Issue Analysis of Natural Bioactive Compounds in Plant, Food, and Pharmaceutical Products Using Chromatographic Techniques)

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