New 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.

The possibility of improving the detection of 1,1-dimethylhydrazine (unsymmetrical dimethylhydrazine, UDMH) by HPLC-SPD under preliminary derivatization with 2-nitrobenzaldehyde (2NBA) and 4‑nitrobenzaldehyde (4NBA) in water with micellar catalysis is studied. The conditions for the derivatization of UDMH (pH, concentrations of reagent and surfactant, temperature, and reaction time) are optimized. The derivatization reactions proceed completely at pH 9 in the presence of 87 mM sodium dodecyl sulfate (SDS) solution and an excess of reagents at room temperature for 45 and 30 min for 2NBA and 4NBA, respectively. Quantitative yield of the reaction products, which is found by the absence of UDMH in the reaction mixture with ion chromatography, is achieved under these conditions. The micellar catalysis allows derivatization under milder conditions and provides the completeness of the reaction under low UDMH concentrations, which expands the linear range of the concentrations determined. A ZORBAX Eclipse Plus C18 chromatographic column (150 × 3.0 mm × 3.5 μm) was used for HPLC-SPD detection of UDMH, and a mixture of acetonitrile and 10 mM ammonia buffer solution at pH 7 (50/50, vol %) at a flow rate of 0.7 mL/min in isocratic mode was used as a mobile phase. The 2NBA and 4NBA dimethylhydrazones were detected at the wavelengths of 308 and 394 nm, respectively. The detection limits for UDMH ( S / N = 3) were 3 and 1.5 μg/L for 2NBA and 4NBA, respectively. The chromatographic analysis time was 15 min. The method developed for water analysis provides a simple, sensitive, and reproducible detection of UDMH in the concentration range of 5–1000 μg/L by the HPLC-SPD method without additional concentration.

This review is devoted to the most hydrolytically stable and widely used polymeric substrates based on a styrene–divinylbenzene copolymer (PS–DVB) which can be used as stationary phases (e.g., in reversed-phase chromatography (RP HPLC)) without modification and can be subjected to multistage surface functionalization to increase the selectivity and efficiency of the final sorbents (e.g., in ion chromatography (IC)). The first chapters of the review consider various production methods of PS–DVB substrates, their main structural physicochemical characteristics, as well as various methods of analysis of the surface and porous structure and their comparison between each other. There are quite a few reviews on the synthesis and properties of polymer materials in the published sources; however, there are almost no data on the interrelation of the physicochemical characteristics of the substrates and chromatographic properties of stationary phases in HPLC. Because of this, the main aim of this review is to find the regularities of the effect of the structural parameters of PS–DVB (particle size, specific surface area, pore size) on the chromatographic properties of sorbents in HPLC.

One of the most important challenges for soil science is to determine the limits for the sustainable functioning of contaminated ecosystems. The response of soil microbiomes to kerosene pollution is still poorly understood. Here, we model the impact of kerosene leakage on the composition of the topsoil microbiome in pot and field experiments with different loads of added kerosene (loads up to 100 g/kg; retention time up to 360 days). At four time points we measured kerosene concentration and sequenced variable regions of 16S ribosomal RNA in the microbial communities. Mainly alkaline Dystric Arenosols with low content of available phosphorus and soil organic matter had an increased fraction of Actinobacteriota, Firmicutes, Nitrospirota, Planctomycetota, and, to a lesser extent, Acidobacteriota and Verrucomicobacteriota. In contrast, in highly acidic Fibric Histosols, rich in soil organic matter and available phosphorus, the fraction of Acidobacteriota was higher, while the fraction of Actinobacteriota was lower. Albic Luvisols occupied an intermediate position in terms of both physicochemical properties and microbiome composition. The microbiomes of different soils show similar response to equal kerosene loads. In highly contaminated soils, the proportion of anaerobic bacteria-metabolizing hydrocarbons increased, whereas the proportion of aerobic bacteria decreased. During the field experiment, the soil microbiome recovered much faster than in the pot experiments, possibly due to migration of microorganisms from the polluted area. The microbial community of Fibric Histosols recovered in 6 months after kerosene had been loaded, while microbiomes of Dystric Arenosols and Albic Luvisols did not restore even after a year.

Novel stationary phases based on aminopropyl silica gel covalently modified with poly(ethylene glycol) (PEG) with different matrix-to-polymer mass ratios are obtained. The chromatographic properties of the adsorbents are studied using the Tanaka test procedure for hydrophilic stationary phases (and by way of example of separating model mixtures of sugars, amino acids, and water-soluble vitamins). It is shown that varying the thickness of the layer of (PEG) not only affects the efficiency but also makes it possible to tailor the selectivity toward polar analytes in the hydrophilic interaction liquid chromatography mode.

A simple, rapid, and sensitive method is developed for the simultaneous determination of hydrazine, methylhydrazine, and 1,1-dimethylhydrazine in waters based on precolumn derivatization with benzaldehyde and the determination of the resulting products by reversed-phase HPLC with spectrophotometric detection at 300, 282, and 298 nm, respectively. The effect of imine and micellar catalysis is applied for the first time to obtain hydrazine derivatives on their simultaneous presence. The conditions of derivatization are chosen: the type, pH and concentration of the buffer system; the concentration of the reagent and the surfactant; and the temperature and duration of the reaction. It is found that the derivatization reaction proceeds completely at pH 9.4 in the presence of a catalytic system based on 0.6 M ammonium and 87 mM sodium dodecyl sulfate, and also 3.5 mM reagent at room temperature for 5 min. The quantitative yield of the derivatization products is confirmed by ion chromatography. The limits of detection (S/N = 3) without additional preconcentration are 0.3, 2.3, and 1.3 μg/L, and the linearity range is 1–500, 7–1000, and 5–1000 μg/L for hydrazine, methylhydrazine, and 1,1-dimethylhydrazine, respectively.

Evaluation of the chromatographic properties of covalently bonded hyperbranched stationary phase based on poly(styrene-divinylbenzene) (PS-DVB) and containing zwitterionic fragments in the structure of functional layer was conducted in suppressed ion chromatography (IC), reversed phase high performance liquid chromatography (RP HPLC), and hydrophilic interaction liquid chromatography (HILIC) modes. Besides the possibility of resolving 20 inorganic anions and organic acids using KOH eluent in suppressed IC, prepared resin provided the separation of alkylbenzenes in RP HPLC, water-soluble vitamins, amino acids, and sugars in HILIC mode. Trends in the retention of hydrophobic and polar analytes on the prepared stationary phase indicated the dominating effect of analyte nature on the retention mechanism and proved satisfactory hydrophilization of PS-DVB surface with hyperbranched functional layer for retaining polar compounds. The obtained results revealed good prospects of using hydrophobic PS-DVB substrate for preparing stationary phases for mixed-mode chromatography.

In this work, simple, rapid and highly sensitive method of hazardous chemical 1,1-dimethylhydrazine (unsymmetrical dimethylhydrazine, UDMH) determination based on pre-column derivatization with unsubstituted aromatic aldehydes and reversed-phase high performance liquid chromatography-ultraviolet-tandem mass spectrometry (RP HPLC-UV-MS/MS) has been developed. Along with benzaldehyde, commercially available aromatic aldehydes, namely: 2-naphthaldehyde, 2-pyridinecarboxaldehyde, and 2-quinolinecarboxaldehyde, were used as derivatizing reagents in the analysis of hydrazines for the first time. The reactions were studied in a wide pH range by varying reaction time and other conditions. A slightly alkaline pH 9 was shown to be optimal for the derivatization of UDMH by aromatic aldehydes. The quantitative yield of derivatization products under the established conditions was confirmed by HPLC analysis with ampemmetric detection. For all studied reagents, wide linear ranges of concentrations (0.01-1000 mu g/L) in natural water samples were observed. The limits of detection for UDMH in natural water were in the 3.7-130 ng/L range. 2-Quinolinecarboxaldehyde was selected as the most appropriate reagent for HPLC-UV-MS/MS determination of UDMH. In case of using this reagent, the accuracy was in the range of 97-102%, and precision, expressed as RSD was less than 8%. The developed approach does not require laborious stages of pre-concentration and isolation of UDMH from natural water components.

The possibility of improving the HPLC-UV determination of 1, 1-dimethylhydrazine (unsymmetrical dimethylhydrazine, UDMH) with preliminary derivatization with 2-nitrobenzaldehyde (2NBA) and 4-nitrobenzaldehyde (4NBA) in an aqueous medium when using micellar catalysis of the reaction to obtain the derivatives is studied. Conditions of UDMH derivatization (pH, concentrations of the reagent and surfactant (SAS), temperature and reaction time) were optimized. It is shown that complete derivatization occurs at room temperature during 45 and 30 min (for 2NBA and 4NBA, respectively) at pH 9 in the presence of 87 mM sodium dodecyl sulfate (SDS) and the excess content of the reagents. Ion chromatography was used to prove the quantitative yields under conditions of derivatization by the absence of UDMH in the reaction mixture. Micellar catalysis provides the completeness of derivatization carried out under milder conditions and in the region of low UDMH concentrations thus expanding the linear range of UDMH determination in water. ZORBAX Eclipse Plus C18 column (150 × 3.0 mm, 3.5 μ m) was used for separation of the components. A mixture of acetonitrile and 10 mM ammonia buffer solution pH 7 (50/50 vol.%) at a flow rate of 0.7 ml/min in isocratic mode was used as a mobile phase. Detection of dimethylhydrazines (2NBA and 4NBA) was performed at 308 and 394 nm, respectively. The obtained detection limits of UDMH ( S / N = 3) were 3 and 1.5 μ g/L for 2NBA and 4NBA, respectively. Duration of chromatographic analysis was 15 min. The developed technique of water analysis provides simple, sensitive and reproducible HPLC-UV determination of UDMH in a concentration range of 5 – 1000 μ g/L without additional preconcentration.

The review covers the research of the Laboratory of Chromatography of the Division of Analytical Chemistry of the Department of Chemistry of Moscow State University in the development of new stationary phases for hydrophilic interaction liquid chromatography and ion chromatography performed in 2007–2017. The principles that guided the team in selecting matrices for each type of adsorbents, approaches to the modification of surface, and the methods of forming functional layers are discussed. The revealed regularities of changes in the chromatographic properties of materials on varying the structural fragments of the functional layers are described in detail, which enabled the authors to develop approaches to obtaining stationary phases that are not inferior to commercial analogs in efficiency and selectivity.

Using an example of tetraphenyltin (TePT), a new method is developed and tested for the isolation and preconcentration of toxic organometallic compounds from soils. It consists in the preconcentration of the target component in an organic layer formed after the splitting of a microemulsion (ME), followed by the determination of TePT by reversed-phase HPLC with spectrophotometric detection. The dependence of the TePT concentration factor in the organic layer formed after the splitting of the ME on the composition of the ME is studied. It is found that, in using a ME of the composition sodium dodecyl sulfate–n-hexane–n-butanol–water (3 : 1.5 : 6 : 89.5, by volume), the concentration factor is maximal and equal to 10. The limit of detection for TePT is 0.1 ng/mL.

A method for identifying straits of rocket kerosene (RG-1 and T-1 brands) and various types of hydrocarbon fuels (aviation fuel TC-1 and diesel fuel) in soil has been developed. The proposed version of identification is based on the preliminary separation of the main components by gas chromatography and their mass spectrometric detection followed by the processing of the data obtained by chemometric methods of analysis (principal component analysis and projection on latent structures with discriminant analysis) using the “MZmineZ,” “iMet-Q,” and “MetaboAnalyst” software. A possibility of the application of the developed approach to the typification of saturated oil fractions of different origin is illustrated.

Four covalently-bonded hyperbranched anion exchangers based on poly(styrene-divinylbenzene) (PS-DVB) substrate with different structure of the functional layer were prepared using mono- and dianionic amino acids such as glycine, β-alanine, aspartic acid, and glutamic acid in the internal part of the functional layer. Selectivity of all anion exchangers toward weakly retained organic acids was investigated at different temperatures in order to evaluate the effect of the number of carboxylic groups in the functional layer and its hydrophilicity on the separation. It was found that dianionic amino acids used in the first modification cycle of hyperbranching provide the best resolution for mono- and divalent organic acids, which makes the number of carboxylic groups in the structure of amino acid a key factor in the separation of such analytes with covalently-bonded hyperbranched anion exchangers, while the role of amino acid hydrophilicity is not that significant. Stationary phases prepared using aspartic and glutamic acids provided baseline resolution for quinic, glycolic, acetic, lactic, formic, and galacturonic acids, which are not resolved to baseline with modern commercially available anion exchangers; the increase of temperature was found to be favorable for improving the resolution even further.

In this paper, we assessed snow pollution by nitrogen-containing substances including rocket propellants - UDMH (unsymmetrical dimethylhydrazine, (CH3)(2)NNH2) and NT (nitrogen tetroxide, N2O4) - and their transformation products (NDMA (nitrosodimethylamine, (CH3)(2)NNO), NO3-, NO2- and NH4+) within the falling regions (FRs) of the first and second stages of Proton-M rockets launched from the Baikonur Cosmodrome. At the first stage FR in Central Kazakhstan, snow with a pH range from 1.7 to 9.0 was contaminated by N-containing substances (maximal value in g/L): UDMH - 0.27, NDMA - 0.04, NO3- - 19, NH4+ - 0.04 and NO2- - 0.13. The first stage landing resulted in snow contamination by soil dust particles and N-containing substances at a rate of 13 g/m(2) and 82 mg/m(2)/day, respectively. The maximal permissible addition (MPA) for UDMH, NDMA and NO3- to the 0-5 cm layer of soil was estimated at 0.06, 0.006 and 70.2 mg/m(2), respectively. At the second stage FR in the NE Altai, substances released by space transportation were absent and the concentration of NO3- and NH4+ corresponded to the natural background level. The index of contamination (IC) was used for characterizing the degree of snow contamination by N-containing substances. A simulation model was developed for analysing the dependence of snow contamination by rocket propellant components on the weather parameters. (C) 2019 Elsevier B.V. All rights reserved.