The possibility of the elution of hydrophilic organophosphorus substances using a concentration gradient of formic acid in an aqueous mobile phase on a Hypercarb porous graphitized carbon sorbent is studied. The analytes are detected on a monoquadrupole mass spectrometer. The retention of analytes is studied by varying the composition of the mobile phase before injection of the sample solution. It is shown that the effect of the stepwise gradient elution on the retention of analytes is primarily due to the state of the sorbent surface rather than the elution ability of the phases. The displacement “quasi-ion exchange” mechanism of analyte retention seems to be most probable.

Electromodulated liquid chromatography (EMLC) allows controlling the retention times of some ions on a carbon sorbent due to the application of electric potential. A simplified two-electrode setup was proposed for EMLC with standard columns. Instead of simultaneous application of constant potential with chromatographic measurements the possibility of working in zero-current mode after preliminary polarization has been shown. Potentiostatic charging of HypercarbTM TM under constant potential and the following measurement of open circuit potential (OCP) was suggested before recording the chromatogram. OCP appeared to be a more reliable parameter than the applied potential to control the sorbent state and its influence on the chromatographic parameters. Linear dependence of retention time on OCP was obtained as a proof of concept. The anodic charging of the sorbent resulted in the highest stability of the sorption parameters in self-powered regime: the retention of analytes in the absence of external potential is preserved for 3-4 h of chromatographic experiment.

The second and final part of the review. Provides general information about sub- and supercritical extraction (pressurized liquid extraction, subcritical water extraction, supercritical fluid extraction), matrix solid-phase dispersion and the QuEChERS method. Based on an analysis of review works, information on the features of sample preparation using these methods is systematized, experimental parameters affecting extraction efficiency are considered, and examples of using these methods for isolating organic compounds in the analysis of solid environmental samples, food products, and plants are given.

A method is proposed for the highly sensitive determination of chloro- and nitrophenols in aqueous solutions, including the preconcentration of analytes on magnetic hydrophobized silica and their determination in the concentrate by liquid chromatography with mass spectrometric detection. The conditions for the determination of chloro- and nitrophenols by chromatography–mass-spectrometry are optimized, and conditions for the sorption preconcentration of phenols in the batch mode are selected. The calibration dependence is linear in the analyte concentration range 2–50 μg/L. The limits of detection for analytes by the proposed method are lower than the MPC of phenols in natural waters. The accuracy of the determination of phenols is confirmed by the analysis of natural water using the spike-recovery test.

A method is proposed for the HPLC separation of a mixture of carboxylic acids on a porous graphitized Hypercarb adsorbent under the conditions of gradient elution with formic acid solutions. The analytes were detected using a single quadrupole mass spectrometer. The stepwise gradient of formic acid without an addition of an organic solvent made it possible to achieve good resolution of the analyte peaks and decrease the limits of detection by a factor of 4.4–17.8 compared to their separation with 0.1% formic acid under isocratic conditions. The effect of methanol on the separation of analytes is less pronounced.

The sorption and desorption of a number of hydrophilic organophosphorus substances (alkylphosphonic and O-alkylalkylphosphonic acids, glyphosate, glufosinate, and aminomethylphosphonic acid) from an aqueous medium on porous graphitized carbon (Hypersep Hypercarb sorbent) was studied. It was shown that the indicated analytes are quantitatively extracted on minicolumns of the size 30 × 2.1 mm at a solution flow rate of 0.5–0.75 mL/min. For the effective desorption of alkylphosphonic acids, it was proposed to use a 0.5% aqueous solution of ammonium formate; for O-alkylalkylphosphonic acids, subcritical water at 200°C; and for glyphosate, glufosinate and aminomethylphosphonic acid, a 1% ammonia solution in 80% methanol. Under these conditions, high concentration factors for analytes (90–150) can be achieved.

The review discusses preparation methods, structure, and features and prospects of using carbon adsorbents, primarily, porous graphitized carbon, for the separation and preconcentration of hydrophilic organic substances in aqueous solutions. The mechanisms of the adsorption of such substances, possibilities of using porous graphitized carbon under extreme conditions, and numerous examples of solving specific problems are presented.

A method for the HPLC determination of glyphosate, aminomethylphosphonic acid, and glufosinate using the gradient separation of analytes on a Hypercarb porous graphitized carbon adsorbent and an aqueous solution of ammonium formate and ammonia as a mobile phase is proposed. Analytes are detected using quadrupole and three-quadrupole mass spectrometers. In order to increase the retention of the analytes, the chromatographic column is washed with water before the injection of a sample solution. This procedure results in a three- to fourfold increase in the retention factors of the analytes in comparison with the analogues described in the publications.

Аккумулятивная функция болот тесно связана со способностью торфа накапливать поступающие извне элементы. В связи с тем, что для болот является характерным преобладание поверхностного стока, корректное описание сорбционных свойств верхних слоев торфяной залежи открывает возможности для прогнозирования процессов переноса тяжелых металлов. В настоящей статье предложено применение модели реактора идеального вытеснения для описания процесса динамической сорбции верховым торфом ионов тяжелых металлов (на примере свинца (II) и кадмия (II)). Объектом исследования выбран верховой торф низкой степени разложения, отобранный на Иласском болотном массиве (Россия, Архангельская область) с глубины 0-20 см (фракция 0.1-0.25 мм). Параметры сорбционной системы определяли методом нелинейной регрессии численного решения модели реактора идеального вытеснения. Полученные коэффициенты распределения и массопереноса, позволяют прогнозировать процесс связывания ионов тяжелых металлов в динамических условиях.

A review of works performed by the authors and devoted to the development of new approaches to the preconcentration of organic compounds (phenols, phthalates, polycyclic aromatic hydrocarbons, and other toxic substances) on low-polar adsorbents is presented. Possibilities of the application of calculation methods to the selection of effective adsorbents and optimal concentration conditions and to the prediction of the behavior of analytes in flow adsorption chromatography systems of analysis are discussed. New methods of the adsorption preconcentration of analytes on fluoroplastic and carbon adsorbents, including the use of subcritical water for desorption, are proposed. A short list of procedures developed for water analysis using these preconcentration methods is presented.

The paper considerations of the possibility of the low-temperature (1000°C) and high-temperature (>1500°C) thermal decomposition of solid samples of suspensions and the selective fractional evaporation–condensation of elements in specialized electrothermal crucible and rod atomizers for the purposes of direct atomic-absorption analysis. The approach is applied to analyze samples of riverine and marine suspensions for Ag, Cd, and Tl.

The review shows prospects of the use of subcritical water instead of organic solvents and aqueous–organic mixtures at different stages of analysis. Subcritical water was applied to the extraction of target compounds from natural samples, such as soils, sand, and plant raw materials. The use of subcritical water expands possibilities of HPLC. The use of subcritical water as an eluent in HPLC is complicated by the possible destruction of the adsorbent and the decomposition of substances to be determined at elevated temperatures. Adsorbents based on zirconium and titanium oxides, some polymeric adsorbents, and porous graphitized carbon are stable in the medium of subcritical water. Subcritical water can be used at several stages of analysis, for example, for the extraction and subsequent chromatographic separation of analytes.