卷 74, 编号 10 (2019)

We considered the physicochemical regularities and analytical capabilities of separation methods based on the manifestation of capillary effects in hydrophobic microporous media, namely, liquid–gas chromatography with a stationary gas phase in the pores of a solid-phase substrate and a mass-exchange process in liquid–gas and liquid–liquid systems, carried out in a biporous matrix. The advantages of these methods compared to conventional mass-exchange processes in the same systems in terms of higher efficiency and a possibility of the separation of substances in a continuous mode are shown.

Electrochemical methods of analysis are usually characterized by high sensitivity, ease of automation, and a wide range of analytes and test samples. The development of electrochemical methods of analysis at the present stage is mostly determined by the creation of new nanostructured electrode materials with electrocatalytic properties. The use of such materials ensures an increase in the sensitivity and selectivity of the determination of a number of analytes. Another conventional way to decreasing the limit of detection for electrochemically active substances is the development of new measurement methods for improving the signal-to-noise ratio in nonequilibrium electrochemical methods of analysis. This article is devoted to the consideration of some new electrode materials and methods of electrochemical measurements.

Problems of the development of potentiometric sensors and multisensor systems for the determination of rare-earth elements in aqueous solutions are considered. The efficiency of the approach to the fabrication of sensors based on the application of substances and regularities used in solvent extraction is shown. Possibilities of multisensor systems for the selective determination of individual lanthanides in complex mixtures are demonstrated.

In this study, cloud point extraction‒scanometry as a new, simple and inexpensive method was developed for the separation, preconcentration and determination of trace amounts of brilliant green (BG) and basic fuchsin (BF) in mixture. The method is based on the extraction of analytes simultaneously from aqueous solution using a non-ionic surfactant Triton X-114 as a cloud point extractor. After phase separation, the surfactant-rich phase was diluted with ethanol, digital image of the solution taken with a flatbed scanner and RGB parameters of the enriched analytes were calculated by special software written in visual basic (VB 6). The influence of analytical parameters including pH of system, the concentration of the surfactant, equilibration temperature and time were optimized. The method was linear in the concentration ranges of 0.025‒1.00 and 0.05‒2.50 mg/L with limits of detection of 0.008 and 0.019 mg/L for BG and BF, respectively. The preconcentration factors were 29 for BG and 28 for BF. The enrichment factors were found to be 34 and 16, precision (RSD, %) of the method, 1.9 and 1.3% for BG and BF, respectively. The effects of interfering ions and dyes were investigated. Finally, the proposed method was applied for the determination of BG and BF in real water samples with satisfactory results.

The separation of a long peptide chain without derivatization, without amide columns and by using routine reversed-phase HPLC columns is itself a big task. Increase in the basic nature of the mobile phase as well as in column temperature and low flow rate of the mobile phase were demonstrated to permit the separation of polar compounds containing long peptide chains. The aim of this study was to develop a procedure for the determination of an antithrombing agent Bivalirudin containing a long peptide chain. This method was developed on a Princeton SPHER-C₁₈ 100 Å (4.6 × 250 mm, 5 µm) column and a mobile phase consisting of water-acetonitrile (pH 7, adjusted with triethylamine) in the ratio of 95 : 5. The flow rate was 0.7 mL/min at the thermostat temperature of 45°C. Validation of the method was performed as per the International Conference on Harmonization. The method was applied to the analysis of a pharmaceutical formulation. The developed method was accurate, fast, easy for implementation and economy as it did not require sophisticated equipment or tedious derivatization process.