AbstractTo expand the field of application of anion exchangers based on a copolymer of styrene and divinylbenzene with attached polyethyleneimine, quaternized with glycidol, the following conditions for their synthesis were varied: the amount of the added glycidol, temperature, and duration of synthesis. The influence of these factors on the capacity, selectivity, and efficiency of the resins in the mode of suppressed ion chromatography was studied; in addition, the stationary phases were studied in the mode of hydrophilic interaction liquid chromatography using the Tanaka test. It was shown that the synthesis conditions under study ensure the control of the capacity and selectivity of anion exchangers, while their hydrophilicity changes insignificantly. The behavior of oxoanions on covalently attached resins in the ion chromatography mode was studied for the first time, and the applicability of phases with quaternized polyethyleneimine in the hydrophilic interaction liquid chromatography mode to the separation of sugars, amino acids, water-soluble vitamins, nucleosides, and nitrogenous bases was demonstrated for the first time.

AbstractThe reactivity of coulometric titrants (bromine, iodine, and hexacyanoferrate(III) ions) with respect to the antioxidants (AOs) of beer is evaluated. It is shown that electrogenerated iodine interacts with ascorbic acid and sulfur-containing compounds, but does not oxidize phenolic AOs. The stoichiometric coefficients of reactions of phenolic AOs with electrogenerated bromine and hexacyanoferrate(III) ions are found. A comprehensive assessment of the antioxidant properties of beer is carried out through overall antioxidant parameters (total antioxidant capacity (TAC) according to the reaction with electrogenerated bromine, ferric reducing power (FRP) according to the reaction with electrogenerated hexacyanoferrate(III) ions, and oxidation by). Sixteen samples, differing in the type of fermentation, variety, and style, are considered. A statistically significant difference between the parameters for individual samples is shown. The TAC and FRP of beer correlate with the total concentration of phenolic compounds and antioxidant activity (r = 0.7175–0.8703 at rcrit = 0.4973), which confirms the correctness of the results obtained using coulometric titration. Differences in the overall antioxidant parameters of the top-fermented and bottom-fermented beers, as well as filtered and unfiltered light and dark beers, are statistically insignificant (p = 0.10–0.82). The change in the overall antioxidant parameters of beer during storage in air is evaluated.

AbstractA novel chemically modified carbon paste electrode based on an inexpensive Ni(salph) complex, where salph is N,N'-bis(salicylidene)-4-methyl-o-phenylenediimine, was prepared for the simultaneous determination of guanine, adenine and thymine. The electrode was characterized by Fourier-transform infrared spectroscopy, field emission scanning electron microscopy, X-ray diffraction, energy dispersive X-ray analysis, thermogravimetric analysis and cyclic voltammetry. The proposed sensor enhanced the anodic peak currents of the nucleobases and could determine them sensitively in 0.1 M phosphate buffer solution (pH 7.0). Moreover, well-separated voltammetric peaks were obtained for guanine, adenine and thymine present in the analyte mixture. Under the optimum operating conditions, the peak currents for guanine, adenine and thymine increased linearly with the increase in the analyte mixture concentration in the ranges of 0.1 to 80, 0.1 to 50 and 15 to 150 μM, respectively. The detection limits for guanine, adenine and thymine were 0.03, 0.03 and 5 μM, respectively. This new approach has been successfully applied for the detection of the corresponding targets in a DNA sample with acceptable recovery.

AbstractRare earth elements (REEs) are currently used in fertilizers, but their behavior in the soil–plant system remains poorly studied. The assessment of the binding of REEs to various organomineral phases of soils remains an important task. Using soddy-podzolic soil and typical chernozem as examples, we performed a comparative study of the dynamic fractionation of REEs in a rotating coiled column (RCC) and a microcolumn (MC). We isolated the exchangeable fraction, specifically adsorbed fraction, and fractions bound to manganese oxides, bound to organic matter, and bound to amorphous and weakly crystallized iron and aluminum oxides using, 0.05 M Ca(NO3)2, 0.43 M CH3COOH, and a 0.1 M NH2OH·HCl solution (pH 3.6), a 0.1 M K4P2O7 solution (pH 11.0), and a 0.1 M (NH4)2C2O4 solution (pH 3.2), respectively. Concentrations of elements in the initial samples and eluate fractions were determined by atomic emission spectrometry and inductively coupled plasma mass spectrometry. The results suggest that the main extractable REE form (up to 40% of the total content) is provided by organometallic complexes extracted with a 0.1 M K4P2O7 solution. For chernozem (soils with a high content of organic matter), fractionation in the RCC and MC yielded comparable results. For soddy-podzolic soil, some differences were observed in the isolation of the first three fractions: exchangeable, specifically adsorbed, and bound to manganese oxides. Both RCC and MC can be successfully used for the dynamic fractionation of REE in soils; however, it is preferable to use an MC in analyzing many samples as a simpler and more affordable device.

AbstractA novel class of reagents (L1–3) containing arylazopyrazole moiety linked to a Schiff base have been synthesized and investigated for anion sensing applications. All three compounds exhibited excellent sensitivity and selectivity toward selective colorimetric detection of F– in dimethyl sulfoxide. F– sensing mechanisms have been explored by various spectroscopic techniques, viz., 1H NMR, IR, UV-visible, and fluorescence spectroscopy. A clear qualitative and quantitative detection of F– was possible with specificity and good sensitivity with L2 giving optimum results. The LOD value of L2 toward F– was found to be 7 µM. These reagents were applied for fluoride detection in commercial toothpaste as well.

AbstractA voltammetric sensor was developed based on a glassy carbon electrode with aluminophosphate zeolite finely dispersed on its surface, modified with a polyelectrolyte complex of chitosan with succinyl chitosan and betulinic acid, for the selective detection and determination of naproxen enantiomers. The electrochemical and analytical characteristics of the sensor were studied, and the effective electrode surface area (A = 9.8 ± 0.5 mm2) and charge transfer resistance (Ret = 649.9 ± 0.4 Ω) were calculated. In determining naproxen enantiomers, calibration characteristics are linear in the range from 2.5 × 10–5 to 1 × 10–3 M with limits of detection of 1.1 × 10–7 and 1.5 × 10–7 M and limits of quantification of 3.6 × 10–7 and 4.9 × 10–7 M for R- and S-naproxen, respectively. The sensor is more sensitive to R-naproxen (∆Ep = 60 mV, ipR/ipS = 1.40). The proposed sensor was used to recognize and determine naproxen enantiomers in human urine and plasma samples. Statistical evaluation of the results by the standard addition method showed that there was no systematic error.

AbstractFor the first time, an UPLC-QTOF-MS method was developed and validated to simultaneously estimate dronedarone (DDN) and its four unlisted pharmacopoeial impurities: DDN impurities A, B, C, and D. UPLC separation was performed for 6 min on a BEH C18 (50 × 2.1 mm, 1.7 µm) columnwith 0.1% formic acid in water (A) and acetonitrile (B) as mobile phase delivered in gradient at a constant flow rate of 0.6 mL/min. Mass spectrometric detection was performed in ESI-QTOF-MS. The LOD and LOQ values for the analytes ranged from 0.5 to 10 and 0.8 to 75 ng/mL, respectively. The method was found to be linear for all analyte ranges with r2 values ≥0.9998. The method was precise with %RSD values ≤6.5% and overall analyte recovery was found to be 99.8 ± 1.0%. A novel, sensitive, selective, specific, linear, and accurate UPLC-QTOF-MS method was developed and validated to simultaneously estimate DDN and its impurities which are not listed in the pharmacopoeia.

AbstractHerein, comparative studies were conducted on different species of Pleurotus mushroom (Pleurotus osteratus, Pleurotus eryngii, Pleurotus sajor caju, Pleurotus florida, and Pleurotus roseus), extracted in two different solvent systems: dichloromethane (DCM)–ethanol (Et) with the ratio of 1 : 1 (v/v) and 50% (v/v) ethanol. Comparably, 50% (v/v) ethanolic crude extract had a considerably higher extraction yield and total phenolic, carbohydrate, and protein content. Owing to a high total phenolic yield, 50% (v/v) ethanolic crude extract had better ability to scavenge 2,2-diphenyl-1-picryl-hydrazyl-hydrate and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid radical. Contrarily, DCM−Et crude extract showed strong cytotoxic potential against the human breast cancer cell line (MD-MBA-231) and murine skin cancer cell line (B16F10). High-performance thin layer chromatography based methods were developed and validated as per the International Council for Harmonisation Q2(R1) for the determination of ergosterol. Ergosterol content in DCM−Et crude extract correlates with its cytotoxic potential.

AbstractThe review summarizes the results of publications on methods for determining arsenic in metallurgical materials from 2000 to 2022.

AbstractA reliable and environmental analytical method was developed for the direct determination of tetracycline using flow injection analysis (FIA) and batch procedures with spectrophotometric detection. The developed method is based on the reaction between a chromogenic reagent (vanadium (III) solution) and tetracycline at room temperature and in a neutral medium, resulting in the formation of an intense brown product that shows maximum absorption at 395 nm. The analytical conditions were improved by the application of experimental design. The proposed method was successfully used to analyze samples of commercial medications and verified throughout the concentration ranges of 25–250 and 3–25 µg/mL for both FIA and batch procedures, respectively. The limits for quantification and detection were 37 and 11 µg/mL for the FIA procedure, respectively, while were 5 and 1.5 µg/mL for the batch procedure, respectively. The commercial samples were also subjected to an HPLC analysis, and the outcomes were in high agreement with the developed method using suggested procedures. The proposed FIA and batch procedures can be immediately employed in the pharmaceutical sector for quality control of tetracycline during the production processes.

AbstractThe article deals with the development of a method for the determination of diflubenzuron in agricultural products using HPLC with a diode array detector. The samples were extracted with acetonitrile, and then purified by solid-phase extraction using C18E and PSA adsorbents and a Diapak C cartridge. The developed method was tested on the green mass of plants, potato tubers, corn grain, soybeans, sunflower seeds, rapeseed, and vegetable oil in the concentration range from 0.025 to 0.25 mg/kg. The average values of recovery were 81–91% with an error of 1.3–2.3%.

AbstractA simple and selective reversed-phase high performance liquid chromatography method was developed and validated for the quantification of 4-chloroaniline, 2-chloro-N-(4-chloro-2-(2-chlorobenzoyl)phenyl)acetamide and 2-iodo-N-(4-chloro-2-(2-chlorobenzoyl)phenyl)acetamide in lorazepam. 4‑Chloroaniline is used as a raw material and 2-chloro-N-(4-chloro-2-(2-chlorobenzoyl)phenyl)acetamide and 2-iodo-N-(4-chloro-2-(2-chlorobenzoyl)phenyl)acetamide are formed as intermediates in the synthesis of anxiety disorder active pharmaceutical ingredient lorazepam. This method provided excellent sensitivity and a typical target analyte level of 150 ppm. This method was developed on an Agilent poroshell 120 EC-C18 (100 × 4.6 mm, 4 µm) column and a photo diode array detector. The proposed method is specific, linear, accurate and precise. The calibration curve was linear over the concentration range of LOQ to 120% with a correlation coefficient of 0.99. This method has low limits of detection and quantification for all the analytes. Accuracy was observed within the range of 85–115% for all the analytes. The developed method was validated as per the ICH guidelines in terms of specificity, precision, limit of detection, limit of quantification, linearity range and accuracy.

AbstractTo expand the available tools for the analysis of samples of biological and plant origin of small mass (10–20 mg) using ICP MS, we developed a construction made of three compact teflon reaction minivessels (inserts) of an internal volume of 3 mL, placed in a standard autoclave (EasyPrep) of a volume of 100 cm3 of a MARS-5 microwave system (CEM). The acid digestion of samples in reaction minivessels requires no more than 1.5 mL of highly pure acids. The digestion of samples proceeds in the common gas atmosphere of a standard autoclave filled with a needed volume of acids of pure for analysis grade. The method was tested on reference materials of plants and biological sample. The results obtained are in agreement with the certified values. The developed method ensures the decrease of the detection limits and obtaining new data on the concentrations of B, Ga, Y, Nb, Tl, Bi, and a number of rare-earth elements in the reference materials.

AbstractThe present work describes the development of molecular iodine mediated facile and sensitive method for the spectrophotometric estimation of tolfenamic acid in pharmaceutical and veterinary formulations. Here, in the presence of iodine, the secondary amine of tolfenamic acid coordinates with the lone pair of available electrons with iodine, which results in the formation of hyper iodine complex of tolfenamic acid. The newly formed colored ion complex showed the absorbance maximum at 359 nm. The method was validated as recommended in ICH guidelines. The method was linear over the concentration range of 0.01–0.07 µg/mL (r2 = 0.9998) with the limits of detection and quantitation of 0.002 and 0.006 µg/mL, respectively. Intra-day (mean recovery of 99.7%) and inter-day (mean recovery of 100.9%) method precision was determined. The mean recovery of the accuracy study is between 99.0–100.5%. The method was found to be robust and suitable for assay of tolfenamic acid in pharmaceutical and veterinary formulations.

AbstractThe current study highlights the systematic quality by design assisted creation of an efficient analytical technique for the estimation of rutin and catechin in corn silk extract tablets. Quercetin was considered as an internal standard. Response surface methodology in the design of experiments was used for identifying key material attributes and critical process parameters that influence the designated critical analytical attributes. Separation was achieved on the HSS C18 column (100 × 2.1 mm, 1.8 μm). The effects of acetonitrile content (v/v), flow rate, and column temperature on the retention times of the two drugs and their resolution and the number of theoretical plates were investigated and optimized. The optimum chromatographic conditions within the design space were found to be an isocratic mobile phase consisting of buffer and acetonitrile (61.5 : 38.5, v/v) with a flow rate of 0.29 mL/min and a run time of 4 min. The retention times of rutin and catechin were found to be 1.9 and 2.8 min. Different validation parameters were established, and the approach was validated in agreement with the ICH and FDA requirements. Data analysis using statistical methods has revealed that the method is reliable, accurate, and robust.

AbstractVarious methods for the oxidation of different types of carbon nanotubes (CNTs) in nitric acid and a mixture of nitric and sulfuric acids at various temperatures and durations of exposure are studied. Oxidation conditions that provide the high sorption activity of sorbents with respect to REE are found. Oxidized CNTs are characterized by acid-base titration and scanning electron microscopy, and the electrokinetic (ζ) potential of nanotube suspensions is determined as a function of pH. The elemental composition of CNTs is determined by ICP MS/AES methods. The sorption capacity of the oxidized CNTs with respect to a wide range of elements is determined. Their unique selectivity with respect to REE is revealed. A possibility of using oxidized CNTs for the efficient sorption preconcentration of REE with the aim to determine their ultralow concentrations in rocks is proved.

AbstractThis work is a continuation of a study on the use of chemical gas sensors and a portable “electronic nose” for diagnosing obesity and related pathologies in children in a hospital. Using a portable Bio-8 device, 330 volatile skin compound profiles were measured in the forearm region on an empty stomach in various states of children with various diseases during inpatient examinations and treatment in the endocrinology department. Monitoring changes in the profile of volatile skin compounds during the period of hospital stay in obese children made it possible to identify priority metabolic disorders in multiple pathological disorders and diagnoses by a characteristic set of chemical biomerkers of processes, reliably detected in skin secretions on the right forearm. Multiparametric data of the “electronic nose” were processed by principal component analysis to assess ranking of the results into the groups “Normal” and “Obesity with a risk of the development of type 2 diabetes mellitus (DM)”. Based on the highly informative parameters of the sensor array, changes in the chemical composition of the skin gas profile on the right forearm during the period of patients’ stay in the hospital and the effectiveness of standard approaches in each specific case were evaluated, and the personalization of treatment was thus increased. Simple calculated parameters and a method for assessing lipid and carbohydrate metabolism disorders based on the signals of eight sensors above the skin measured for 200 s without sampling were proposed. The sensitivity of the method for monitoring changes in the metabolome in a hospital is at least 80%. Specificity for lipid metabolism disorders is 100%; for type 1 diabetes, 100%; and for mixed pathologies varies from 70 to 85%.

AbstractA new binary liquid-liquid extraction technique incorporating 3-hydroxy-2-[1'-phenyl-3'-(p-methoxyphenyl)-4'-pyrazolyl]-4H-chromen-4-one (HPMPC) has been developed for the trace spectrophotometric detection and determination of Zr(IV). The optimal conditions for the formation of Zr(IV)−HPMPC complex in a ratio of 1 : 3 (M : L) were investigated. The resulting complex has yellow color and allows for the micro level measurement of zirconium in a straightforward and cost-effective manner. The process is quick, sensitive (1.073 × 105 L/mol cm) and selective. A good linearity (r = 0.9998) was observed for Zr(IV) in the range of 0.20–0.8 µg/mL. The approach is extremely repeatable with acceptable precision and accuracy (RSD of 0.3%) and can be expanded to include the examination of zirconium in a variety of samples (synthetic, natural and technical). The analytical investigation was successfully extended to DFT calculations to forecast the structural geometry and confirm the complex ultimate stoichiometry. The calculations not only produced an optimal complex structure, but also confirmed the bidentate ligand chelating efficacy by coordinating benzopyran ring to the metal center.

AbstractDespite the constant improvement of complex computer algorithms for the calculation of gas chromatographic retention indices (RIs), the simplest methods for their evaluation based on linear correlations between the indices of structural analogs from different taxonomic groups, RI1 ≈ aRI2 + b, remain important. It is shown that symbatic variations of the first numerical differences of retention indices, \(\Delta _{{{\text{RI}}}}^{1}\) = RIn + 1 – RIn (equivalent to the first derivatives of the retention indices with respect to the structural parameter varied in the group), are the conditions of correctness for such correlations in the simplest groups (substituted methanes). A monotonic variation of \(\Delta _{{{\text{RI}}}}^{1}\) in one of the groups with the presence of extrema in the other group is an unequivocal sign of the absence of a linear correlation between retention indices. If the values of \(\Delta _{{{\text{RI}}}}^{1}\) in one of the groups increase and decrease in the other, the ranking order of compounds in any one of them should be reversed. It is shown that the simplest relationship RI1 ≈ aRI2 + b is also applicable to more complex taxonomic groups (substituted ethanes, benzenes, and naphthalenes), and it allows one not only to estimate the RIs of compounds not yet characterized but also to refine known reference data.

AbstractNew adsorbents based on silica and polystyrene–divinylbenzene (PS–DVB) for hydrophilic interaction liquid chromatography (HILIC) with eremomycin in functional layers were obtained. The chromatographic properties of the new adsorbents were assessed using the Tanaka test for hydrophilic stationary phases and by studying the retention of substances of various classes in HILIC, chiral, and reversed-phase chromatography modes. It was shown that the use of eremomycin to create functional layers leads to an increase in the hydrophilicity of the adsorbents on different types of substrates and ensures the shielding of their charge. Eleven nitrogenous bases, nucleosides with an efficiency of up to 25 000 tp/m, or seven vitamins with an efficiency of up to 40 000 tp/m can be separated on a modified sorbent based on aminopropyl silica, and three different HPLC modes can be implemented on the sorbent with eremomycin based on PS–DVB.