Chromatographic Data Research Articles

New insights into the dissociation of mixed CH4/CO2 hydrates for CH4 production and CO2 storage

Recent but limited studies have shown that multistep slow depressurization based on mixed CH4/CO2 hydrate dissociation can enhance CH4 recovery and increases CO2 storage after CO2 injection into CH4 hydrate [1,2]. For the first time, the resistivity variation and gas recovery and storage variation was investigated to study the change in hydrate saturation and production/storage yield. Lab-scale CH4 and CO2 rich mixed hydrates were synthesized to mimic the production and injection well scenario. The mixed hydrates were synthesized in sandstone with moderate to high water saturation using two different CH4/CO2 gas mixtures. Furthermore, mixed CH4/CO2 hydrates were dissociated three to six steps based on cyclic depressurization. Pressure, resistivity and gas chromatography data were collected. The presence of two thermodynamic stability zones provided an opportunity for additional CH4 recovery and CO2 storage during mixed hydrate dissociation. Gas and water migration between the injection and production well caused CO2 hydrate reformation, improvement in CO2 sweep area and movement of the CO2 hydrate front toward the production well. Multiple peaks in CH4 recovery and CO2 storage suggest major dissociation and reformation. Peak values were independent of mixed hydrate type. Peaks values of CH4 rich hydrates occurred at high pressure than peak values of CO2 rich hydrates. The slight change in resistance during depressurization below pure CH4 hydrate stability pressure confirms the loss of CH4 hydrate mass recovered by the formation of CO2 hydrate mass. This study discusses the correlation between the change in resistivity and type of guest molecule and its concentration and initial water saturation. The results of this study will be useful to explore the application of slow depressurization for the dissociation of CH4/CO2 mixed hydrates to improve CH4 recovery and CO2 storage.

Different behavior of two iso-structural zeolitic imidazolate frameworks in ethane-ethylene separation: Study of H2 -CO2 and CH4 -CO2 separation capacity.

The separation of ethane-ethylene mixtures was evaluated using two zeolitic imidazolate frameworks, which are only different from the assemble metal, as stationary phase from inverse gas chromatography data. The chromatographic profiles exhibited peaks adequately resolved. Separation is attributed to the pore sizes of the adsorbents that discern between ethane and ethylene molecule shapes and closed kinetic diameters. The adsorption heats were estimated for each probe molecule from the slopes of the straight lines at four temperatures. The evaluated materials are iso-structural compounds with the unique difference of assembling metal (cobalt and zinc). Cobalt material showed atypical adsorption of ethane over ethylene, which was observed taking into account the retarded elution of the paraffin. Therefore, the anomalous behavior could be ascribed to the presence of cobalt(II). Structural characterization of both materials was performed by X-ray powder diffraction, X-ray photoelectronic spectroscopy, and thermogravimetry, while morphological characterization was performed by scanning electron microscopy. H2 -CO2 and CH4 -CO2 mixtures separation were also evaluated by inverse gas chromatography. Both materials were able to separate these two mixtures. CO2 was the highest retained probe molecule due to the presence of quadrupole moment.

A New Definition of the Stationary Phase Volume in Mixed-Mode Chromatographic Columns in Hydrophilic Liquid Chromatography.

Polar columns used in the HILIC (Hydrophilic Interaction Liquid Chromatography) systems take up water from the mixed aqueous–organic mobile phases in excess of the water concentration in the bulk mobile phase. The adsorbed water forms a diffuse layer, which becomes a part of the HILIC stationary phase and plays dominant role in the retention of polar compounds. It is difficult to fix the exact boundary between the diffuse stationary and the bulk mobile phase, hence determining the column hold-up volume is subject to errors. Adopting a convention that presumes that the volume of the adsorbed water can be understood as the column stationary phase volume enables unambiguous determination of the volumes of the stationary and of the mobile phases in the column, which is necessary for obtaining thermodynamically correct chromatographic data in HILIC systems. The volume of the aqueous stationary phase, Vex, can be determined experimentally by frontal analysis combined with Karl Fischer titration method, yielding isotherms of water adsorbed on polar columns, which allow direct prediction of the effects of the composition of aqueous–organic mobile phase on the retention in HILIC systems, and more accurate determination of phase volumes in columns and consistent retention data for any mobile phase composition. The n phase volume ratios of 18 columns calculated according to the new phase convention strongly depend on the type of the polar column. Zwitterionic and TSK gel amide and amine columns show especially strong water adsorption.

1-Methylcyclopropene Preserves the Quality of Chive (Allium schoenoprasum L.) by Enhancing Its Antioxidant Capacities and Organosulfur Profile during Storage.

The quality, antioxidant capacities, and organosulfur profile of chives (Allium schoenoprasum L.) treated with 1-methylcyclopropene (1-MCP) during storage were investigated in this study. The 1-MCP treatment (100 μL/L, fumigation 12 h at 20 °C) effectively inhibited tissue respiration and H2O2 production, enhanced the ascorbic acid (ASA) and glutathione (GSH) content, and promoted the activity of antioxidant enzymes (superoxide dismutase SOD, Catalase CAT, and ascorbic peroxidase APX) during the 5-day storage period at 20 °C. The result further showed that the 1-MCP treatment inhibited chlorophyll degradation, alleviated cell membrane damage, and delayed the chive senescence, with the yellowing rate being reduced by 67.8% and 34.5% in the 1-MCP treated chives on days 4 and 5 of storage at 20 °C, respectively. The free amino acid content of the chive was not affected by the 1-MCP treatment at 20 °C. However, the senescence rate of the chive was not reduced by the 1-MCP treatment when stored at 3 °C. The liquid chromatography data further showed that the 1-MCP treatment induced a 15.3% and 13.9% increase in the isoalliin and total S-alk(en)ylcysteine sulfoxides (ACSOs) content of the chive on day 2 at 20 °C, respectively. Furthermore, there was a strong positive correlation between ACSOs content and CAT/APX activity, indicating that ACSOs probably played a key role in enhancing the antioxidant capacities of the chive during storage at 20 °C. Thus the study efficiently demonstrates that 1-methylcyclopropene preserves the quality of chive (Allium schoenoprasum L.) by enhancing its antioxidant capacities and organosulfur profile during storage.

High-Throughput Detection of an Alkaloidal Plant Metabolome in Plant Extracts Using LC-ESI-QTOF-MS.

Plant alkaloids represent a diverse group of nitrogen-containing natural products. These compounds are considered valuable in drug discovery and development. High-throughput identification of such plant secondary metabolites in complex plant extracts is essential for drug discovery, lead optimization, and understanding the biological pathway. The present study aims to rapidly identify different classes of alkaloids in plant extracts through the liquid chromatography with electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) approach using 161 isolated and purified alkaloids. These are biologically important unique alkaloids belonging to different sub-classes such as isoquinoline, quinoline, indole, tropane, pyridine, piperidine, quinolizidine, aporphine, steroidal, and terpenoid. The majority of these are not available commercially and are known to manifest valuable biological activities. Four pools of a maximum of 50 phytostandards each were prepared, based on their log P value to minimize co-elution for rapid and cost-effective analyses. MS/MS spectra were acquired in the positive ionization mode by using their [M + H]+ and/or [M + Na]+ with both the average collisional energy (25.5-62 eV) and individual collisional energies (10, 20, 30, and 40 eV). Accurate mass, high-resolution mass spectrometry (HR-MS) data, MS/MS data, and retention times were curated for each compound. The developed LC-MS/MS method was successfully used to interrogate and fast dereplicate alkaloids in 13 medicinal plant extracts and a herbal formulation. A total of 56 alkaloids were identified based on the reference standard retention times (RTs), HR-MS spectra, and/or MS/MS spectra. The MS data have been submitted to the MetaboLights online database (MTBLS2914). The mass spectrometric and chromatographic data will be useful for the discovery of new congeners and the study of biological pathways of alkaloids in the plant kingdom.

Discrimination of the Essential Oils Obtained from Four Apiaceae Species Using Multivariate Analysis Based on the Chemical Compositions and Their Biological Activity.

The chemical composition of the essential oils obtained from the aerial parts of four Apiaceae species, namely Elaeosticta allioides (EA), E. polycarpa (EP), Ferula clematidifolia (FC), and Hyalolaena intermedia (HI), were determined using gas chromatography. Altogether, 100 volatile metabolites representing 78.97, 81.03, 85.78, and 84.49% of the total components present in EA, EP, FC, and HI oils, respectively, were reported. allo-Ocimene (14.55%) was the major component in FC, followed by D-limonene (9.42%). However, in EA, germacrene D (16.09%) was present in a high amount, while heptanal (36.89%) was the predominant compound in HI. The gas chromatographic data were subjected to principal component analysis (PCA) to explore the correlations between these species. Fortunately, the PCA score plot could differentiate between the species and correlate Ferula to Elaeosticta species. Additionally, the antioxidant activity was evaluated in vitro using the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH), 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), and the ferric reducing power (FRAP) assays. In addition, the antimicrobial activity using the agar diffusion method was assessed, and the minimum inhibitory concentrations (MICs) were determined. Furthermore, the cell viability MTT assay was performed to evaluate the cytotoxicity of the essential oils against hepatic (HepG-2) and cervical (HeLa) cancer cell lines. In the DPPH assay, FC exhibited the maximum activity against all the antioxidant assays with IC50 values of 19.8 and 23.0 μg/mL for the DPPH and ABTS assays, respectively. Ferula showed superior antimicrobial and cytotoxic activities as well. Finally, a partial least square regression model was constructed to predict the antioxidant capacity by utilizing the metabolite profiling data. The model showed excellent predictive ability by applying the ABTS assay.

Comparative hydrolysis analysis of cellulose samples and aspects of its application in conservation science

Knowledge about the carbohydrate composition of pulp and paper samples is essential for their characterization, further processing, and understanding the properties. In this study, we compare sulfuric acid hydrolysis and acidic methanolysis, followed by GC–MS analysis of the corresponding products, by means of 42 cellulose and polysaccharide samples. Results are discussed and compared to solid-state NMR (crystallinity) and gel permeation chromatography (weight-averaged molecular mass) data. The use of the hydrolysis methods in the context of cellulose conservation science is evaluated, using e-beam treated and artificially aged cellulose samples.

β-Sitosterol Compound from Dichloromethane Extracts of Kalanchoe tomentosa (Crassulacea) Leaves and Inhibition of α-amilase Activity

Kalanchoe tomentosa is one of the plants of the Crassulaceae tribe that can lower blood sugar and contains compounds of terpenoids, flavonoids, alkaloids, saponins, tannins, fatty acids, steroids, and triterpenoids. This study aims to isolate and identify chemical compounds from dichloromethane extract of Kalanchoe tomentosa leaves, as well as to test the inhibitory activity of the α-amylase enzyme. Extraction was carried out by maceration using dichloromethane as a solvent, then dichloromethane extract was purified using column chromatography, the pure isolate was obtained in the form of white powder, and an inhibition test was carried out against the α-amylase enzyme. The thin layer chromatography data of pure isolates compared to pure β-sitosterol are similar. Based on the research data, it can be concluded that the chemical structure of the pure isolate is β-sitosterol, the methylene chloride extract of K. tomentosa leaves has an inhibitory activity against the α-amylase enzyme with an inhibition value of 65%. This value is greater than the positive control of acarbose which only has 37% inhibition and β-sitosterol compound by 6.7%. This value is smaller when compared to the control of acarbose at the same concentration which obtained 5% inhibition.

Multivariate Curve Resolution Alternating Least Squares applied to Chromatographic Data: From the Basics to the Recent Advances

This revision presents applications of multivariate curve resolution alternating least squares (MCR-ALS) applied to chromatographic data. Initially, the fundamentals and recent advances of the MCR-ALS method will be presented. Several critical issues such as data organization, advantages of the modelling, constraints, evaluation of ambiguity and the use for mathematical separation is discussed. An extensive revision of the papers on MCR-ALS applied to chromatographic data reported up to 2020 is presented. A practical example of an innovative application of cholesterol lowering drugs using supercritical fluid chromatography (SFC) is described highlighting important aspects of the method. At the end, a list of links to MCR-ALS algorithms and graphical interfaces developed in Matlab, R and Python 3 is provided.

Improving the sensitivity of estimating CBD and other xenobiotics in plasma samples: Oleamide-induced transient matrix effect

The paper discusses the matrix effect evoked by oleamide (OLA), a compound frequently found in samples processed and/or stored in lab polypropylene vials or disposable syringes. In the case of many substances a higher response for their samples containing OLA than for net solutions is observed. The analyte signal gain resulting from OLA presence in the examined sample depends on the ratio of OLA concentration to analyte concentration. A characteristic feature of the matrix effect evoked by oleamide is its short duration, which makes the chromatographic data (retention value and signal magnitude of examined compound) repeatable and reproducible. The identified “transient matrix effect” may significantly increase the sensitivity of many analytical procedures employing GC. Evoking the transient matrix effect by means of OLA in the experimental analytical quantitation of cannabidiol in plasma allowed to lower its limit of detection (LOD) by more than 50 %.

Applying Log-Normal Peak Fitting to Parallel Reaction Monitoring Data Analysis.

Chromatographic separation is often an important part of mass-spectrometry-based proteomic analysis. It reduces the complexity of the initial samples before they are introduced to mass-spectrometric detection and chromatographic characteristics (such as retention time) add analytical features to the analyte. The acquisition and analysis of chromatographic data are thus of great importance, and specialized software is used for the extraction of quantitative information in an efficient and optimized manner. However, occasionally, automatic peak picking and correct peak boundary setting is challenged by, for instance, aberration of peak shape, peak truncation, and peak tailing, and a manual review of a large number of peaks is frequently required. To support this part of the analysis, we present here a software tool, Peakfit, that fits acquired chromatographic data to the log-normal peak equation and reports the calculated peak parameters. The program is written in R and can easily be integrated into Skyline, a popular software packages that is frequently used for proteomic parallel reaction monitoring applications. The program is capable of processing large data sets (>10 000 peaks) and detecting sporadic outliers in peak boundary selection performed, for instance, in Skyline. In an example data set, available via ProteomeXchange with identifier PXD026875, we demonstrated the capability of the program to characterize chromatographic peaks and showed an example of its ability to objectively and reproducibly detect and solve problematic peak-picking situations.

Bioactive oleanane-type saponins from Hylomecon Japonica

Six undescribed oleanane-type saponins, named as Hylomeconosides L-Q, were isolated from the whole herb of Hylomecon Japonica, their structures were determined by analysis of 1D and 2D-NMR (1H–1H COSY, HSQC, and HMBC) spectroscopic data, mass spectrometry (HRESI-MS) and chromatographic data (GC and LC). Their structures were identified as 3-O-β-D-galactopyranosyl-(1 → 2)-β-D-glucuronopyranosyl gypsogenin 28-O-β-D-galactopyranosyl-(1 → 3)-α-L-rhamnopyranosyl-(1 → 2)-β-L-arabinopyranoside; 3-O-β-D-galactopyranosyl-(1 → 2)-β-D-glucuronopyranosyl gypsogenin 28-O-β-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 2)-β-D-quinovopyranoside; 3-O-β-D-glucuronopyranosyl gypsogenin 28-O-β-D-xylopyranosyl-(1 → 3)-β-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 2)-β-D-quinovopyranoside; 3-O-β-D-xylopyranosyl-(1 → 3)-β-D-glucuronopyranosyl gypsogenin 28-O-β-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 2)-β-D-quinovopyranoside; 3-O-β-D-galactopyranosyl-(1 → 2)-[α-L-rhamnopyranosyl-(1 → 3)]-β-D-glucuronopyranosyl quillaic acid 28-O-β-D-xylopyranosyl-(1 → 3)-β-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 2)-β-D-quinovopyranoside; 3-O-β-D-galactopyranosyl-(1 → 2)-[α-L-rhamnopyranosyl-(1 → 3)]-β-D-glucuronopyranosyl quillaic acid 28-O-β-D-xylopyranosyl-(1 → 3)-β-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 2)-β-D-galactopyranoside. Hylomeconosides L-Q showed selective cytotoxicities against human cancer cell lines A549, AGS, HeLa, Huh 7, HT29 and K562. These results represent a contribution to the chemotaxonomy of the saponins of Hylomecon Japonica and their bioactivities.

Synthesis optimization, DFT and physicochemical study of chitosan sulfates

Chitosan is an important biologically active amino polysaccharide. Water-soluble sulfated chitosan derivatives are widely used as anticoagulant and antiviral drugs. In this study, new methods for sulfamic acid sulfation of chitosan in the presence of urea in 1,4-dioxane and in a deep eutectic solvent representing a mixture of sulfamic acid and urea have been proposed. Mathematical models of sulfation of chitosan in these systems have been built. The obtained sulfated chitosan derivatives have been investigated by Fourier-transform infrared spectroscopy, X-ray diffractometry, atomic force microscopy, gel permeation chromatography, elemental analysis, and the density functional theory. The introduction of the sulfate group into the chitosan molecule was proven by infrared spectroscopy. When using the sulfamic acid/urea mixture, side reactions of carbamation of chitosan have been observed. It has been established from the atomic force microscopy data that the sulfated chitosan film surface consists of spherical particles partially agglomerated with each other. According to the gel permeation chromatography data, sulfated chitosan obtained in different systems, but under the same conditions (temperature and time), has different molecular weight distributions. The molecular weight distribution curve of the sulfated chitosan obtained in the sulfamic acid‒urea‒1,4-dioxane system is significantly shifted to the high-molecular region (Mw ~ 36.6 kDa), while the sulfated chitosan obtained in the sulfamic acid/urea deep eutectic solvent (Mw ~ 27.2 kDa). The density functional theory calculation of chitosan sulfates in the B3LYP/6-31G(d, p) basis set have been made.

Combined Production of Astaxanthin and β-Carotene in a New Strain of the Microalga Bracteacoccus aggregatus BM5/15 (IPPAS C-2045) Cultivated in Photobioreactor.

Simple SummaryMicroalgae are the richest source of natural carotenoids, valuable pigments, which are key components of functional food, cosmetics, drugs and animal feeding. To date, only two genera of green microalgae are widely used for mass production of carotenoids on an industrial scale, Haematococcus and Dunaliella. They produce astaxanthin and β-carotene, respectively, which are among the most useful carotenoids. In doing so one alga produces only one type of a pigment. In this paper we characterize a new strain of the green microalga Bracteacoccus aggregatus BM5/15 (IPPAS C-2045). It can simultaneously produce both carotenoids (up to 13.1 and 47.9% β-carotene and astaxanthin of cell dry mass, respectively). Growth parameters of the strain cultivated in glass bubble-column photobioreactors for commercial cultivation of microalgae were obtained. We also provide data of microscopic observations, pigment and fatty acid profile of the microalga, which are important biotechnological characteristics. Collectively, new data makes B. aggregatus BM5/15 suitable for industrial production of β-carotene, a pro-vitamin A, and astaxanthin, the most powerful antioxidant.Carotenoids astaxanthin and β-carotene are widely used natural antioxidants. They are key components of functional food, cosmetics, drugs and animal feeding. They hold leader positions on the world carotenoid market. In current work, we characterize the new strain of the green microalga Bracteacoccus aggregatus BM5/15 and propose the method of its culturing in a bubble-column photobioreactor for simultaneous production of astaxanthin and β-carotene. Culture was monitored by light microscopy and pigment kinetics. Fatty acid profile was evaluated by tandem gas-chromatography–mass spectrometry. Pigments were obtained by the classical two-stage scheme of autotrophic cultivation. At the first, vegetative, stage biomass accumulation occurred. Maximum specific growth rate and culture productivity at this stage were 100–200 mg∙L−1∙day−1, and 0.33 day−1, respectively. At the second, inductive, stage carotenoid synthesis was promoted. Maximal carotenoid fraction in the biomass was 2.2–2.4%. Based on chromatography data, astaxanthin and β-carotene constituted 48 and 13% of total carotenoid mass, respectively. Possible pathways of astaxanthin synthesis are proposed based on carotenoid composition. Collectively, a new strain B. aggregatus BM5/15 is a potential biotechnological source of two natural antioxidants, astaxanthin and β-carotene. The results give the rise for further works on optimization of B. aggregatus cultivation on an industrial scale.

Electrochemical Determination of the "Furanic Index" in Honey.

5-(hydroxymethyl)furan-2-carbaldehyde, better known as hydroxymethylfurfural (HMF), is a well-known freshness parameter of honey: although mostly absent in fresh samples, its concentration tends to increase naturally with aging. However, high quantities of HMF are also found in fresh but adulterated samples or honey subjected to thermal or photochemical stresses. In addition, HMF deserves further consideration due to its potential toxic effects on human health. The processes at the origin of HMF formation in honey and in other foods, containing saccharides and proteins—mainly non-enzymatic browning reactions—can also produce other furanic compounds. Among others, 2-furaldehyde (2F) and 2-furoic acid (2FA) are the most abundant in honey, but also their isomers (i.e., 3-furaldehyde, 3F, and 3-furoic acid, 3FA) have been found in it, although in small quantities. A preliminary characterization of HMF, 2F, 2FA, 3F, and 3FA by cyclic voltammetry (CV) led to hypothesizing the possibility of a comprehensive quantitative determination of all these compounds using a simple and accurate square wave voltammetry (SWV) method. Therefore, a new parameter able to provide indications on quality of honey, named “Furanic Index” (FI), was proposed in this contribution, which is based on the simultaneous reduction of all analytes on an Hg electrode to ca. −1.50 V vs. Saturated Calomel Electrode (SCE). The proposed method, validated, and tested on 10 samples of honeys of different botanical origin and age, is fast and accurate, and, in the case of strawberry tree honey (Arbutus unedo), it highlighted the contribution to the FI of the homogentisic acid (HA), i.e., the chemical marker of the floral origin of this honey, which was quantitatively reduced in the working conditions. Excellent agreement between the SWV and Reverse-Phase High-Performance Liquid Chromatography (RP-HPLC) data was observed in all samples considered.

Aspects of albendazole metabolism in western lowland gorillas (Gorilla gorilla gorilla) compared to humans and other species assessed by HPLC, LC‐MS, and chiral electrokinetic chromatography

AbstractThe benzimidazole anthelmintic drug albendazole becomes metabolized to chiral albendazole sulfoxide, albendazole sulfone, albendazole 2‐aminosulfone, and other metabolites. High‐performance liquid chromatography with UV absorbance and fluorescence detection, liquid chromatography with mass spectrometry, and chiral electrokinetic chromatography were used to analyze albendazole metabolites in extracts of western lowland gorilla (Gorilla gorilla gorilla) plasma of patients with alveolar echinococcosis and the data are compared to those obtained with human patient samples and to those reported for other species in the literature. The data revealed that the albendazole sulfoxide to albendazole sulfone concentration ratio in gorilla plasma is significantly smaller compared to that in samples of men, rats, dogs, and cattle. It is, however, similar to what was observed in sheep and goats. The (+)‐albendazole sulfoxide to (−)‐albendazole sulfoxide enantiomeric ratio in gorilla blood determined by chiral electrokinetic chromatography was found to be >1 which is comparable to what was observed in humans, dogs, sheep, goats, and cattle but different to mice and rats. Furthermore, the electrokinetic chromatography data suggest that small amounts of albendazole 2‐aminosulfone may be present in plasma of gorillas and humans. The data gathered with the various separation‐based assays illustrate the value of technology featuring different analyte separation and detection principles. This is the first account describing aspects of the albendazole metabolism in gorillas.

Chemometric evaluation of functional components and anti-quorum sensing activity of mulberry leaves from Indian cultivars: a potential contribution to the food industry.

Potential use of many native, easily available vegetal materials for human consumption and value addition is not well recognized. Mulberry, being a traditional industrial crop rich in nutrients and nutraceuticals can be of great importance for the food industry. However, mulberry leaves are mainly being utilized in sericulture and are not exploited for their functional components. Thus, the selection of promising mulberry cultivars, rich in bioactive compounds, like resveratrol and 1-deoxynojirimycin, increase their potential use in functional foods. Chlorogenic acid, myricetin and kaempferol were the major polyphenols present in the nine selected cultivars, in the range 0.001-0.086, 0.003-0.079 and 0.003-0.163 g kg-1 fresh weight (FW), respectively. Protocatechuic acid, epicatechin and rutin were predominantly present in cultivars V-1, G-2 and ML (0.103, 0.080 and 0.121 g kg-1 FW, respectively). Similarly, resveratrol and 1-deoxynojirimycin were highest in cultivars ML and K-2 (0.078 and 0.079 g kg-1 FW, respectively). Leaf extracts of cultivars G-2 and ML were able to effectively inhibit the violacein production with 64.08% and 70.04%, respectively at the concentration of 6mg mL-1 presumably due to a higher content of polyphenols. Chemometric evaluation of chromatographic data showed the intraspecific variability and secondary metabolite co-existence in different cultivars. Considering phytoconstituents, cultivars G-2, ML, K-2 and V-1 could contribute efficiently to the rational utilization of mulberry in agro-food industries. Furthermore, cultivars G-2 and ML leaves can be a new source of quorum sensing inhibitory agents. © 2021 Society of Chemical Industry.

Synthesis of Poly(styrene sulfonyl chloride) via reversible addition-fragmentation chain transfer polymerization and characterization thereof for membrane applications

Reversible addition-fragmentation chain transfer (RAFT) polymerization has been examined for the synthesis of poly (styrene sulfonyl chloride) (PSSC) of high molecular weight and narrow polydispersity index (PDI). PSSC, contains reactive sulfonyl chloride that can allow use of organic solvent for membrane casting, and chemical modification through reactive sulfonyl groups. For PSSC preparation, end-capped styrene i.e. styrene sulfonyl chloride (SSC) is used as a monomer, which is derived from sodium 4-vinylbenzenesulfonate by chlorination with thionyl chloride. Fourier transform infrared spectroscopy, Raman spectroscopy and Proton nuclear magnetic resonance spectroscopy, have been successfully used to confirm the polymer architecture. End-group of PSSC containing RAFT agent (Cyanomethyl N-methyl-N-phenylcarbamodithioate), is also confirmed by fragmentation analysis using Gas chromatography-mass spectroscopy. Evaluation of PSSC by X-ray diffraction and differential scanning calorimetry showed that resulting polymer is predominantly amorphous in nature and has a glass transition temperature of 119 ​°C. Gel permeation chromatography data reveals formation of high molecular weight (84 ​kDa) PSSC with and low PDI (1.4). Moreover, PSSC can be converted to polyelectrolyte and can be crosslinked by interfacial polymerization concept; hence, it would have considerable prospective for membrane preparation for fuel cell and water purification.

RP-18 TLC Chromatographic and Computational Study of Skin Permeability of Steroids.

The skin permeability of steroids, as investigated in this study, is important because some of these compounds are, or could, be used in preparations applied topically. Several models of skin permeability, involving thin layer chromatographic and calculated descriptors, were generated and validated using Kp reference values obtained in silico and then tested on a group of solutes whose experimental Kp values could be found (log Kpexp). The study established that the most applicable log Kp model is based on RP-18 thin layer chromatographic data (RM) and the calculated descriptors VM (molar volume) and PSA (polar surface area). Two less efficient, yet simple, equations based on PSA or VM combined with HD (H-donor count) can be used with caution for rapid, rough estimations of compounds’ skin permeability prior to their chemical synthesis.

Analytical characterization of "etonitazepyne," a new pyrrolidinyl-containing 2-benzylbenzimidazole opioid sold online.

This paper reports on the identification and full chemical characterization of the substance colloquially called "etonitazepyne" or "N-pyrrolidino etonitazene" (2-(4-ethoxybenzyl)-5-nitro-1-(2-(pyrrolidin-1-yl)ethyl)-1H-benzo[d]imidazole), a potent NPS opioid of the 5-nitrobenzimidazole class. Identification of etonitazepyne was performed, on a sample purchased during routine monitoring of the drug market, using GC-MS, HRAM LC-MS/MS, 1 H NMR, and FTIR. The chromatographic data, together with the FTIR data, indicated the presence of a highly pure compound and already indicated a benzimidazole structure. The specific benzimidazole regio-isomer was confirmed using 1 H NMR spectroscopy, resulting in the unambiguous identification of etonitazepyne.