INTERPHASE DISTRIBUTION OF SORBIC ACID DURING EXTRACTION BY COPOLYMERS OF N-VINYLFORMAMIDE AND 1-VINYL-3,5-DIMETНYLPYRAZOL

Abstract

Рurpose. The paper seeks to determine the extraction characteristics of sorbic acid using a copolymer of N-vinylformamide and 1-vinyl-3,5-dimethylpyrazole as an extractant. The complexation process in the analyte-copolymer system is studied, and a method for fi nding a preservative by means of capillary electrophoresis is suggested. Methods and methodology. The extraction of sorbic acid was carried out using a water-soluble copolymer obtained by radical co-polymerization in dioxane. Using common formulas, the distribution coeffi cients and the degree of extraction of the analyte were calculated for a single extraction in the presence of a saliver – a saturated solution of ammonium chloride. Results. The conditions for the most effi cient extraction of sorbic acid were determined: the characteristic viscosity of the polymers, the concentration of the polymer solution and the analyte, the volume ratio of the phases, the ratio of the molar fractions of N-vinylformamide to 1-vinyl-3,5-dimethylpyrazole. The extraction characteristics of the interfacial distribution of sorbic acid between the water-salt solution and the extractant were calculated. The concentration of the co-polymer and the ratio of the volumes of the equilibrium phases at which the maximum degree of sorbic acid extraction is achieved were determined. It was observed that due to the formation of hydrogen bonds during the self-association of molecules, an increase in the concentration of sorbic acid may not lead to an increase in the degree of its extraction. To determine the sorbic acid after the extraction, an external standard method was used including the construction of multi-point calibration curves. Conclusions. The dependence of the interphase distribution on the structure of the analyte, as well as the complex-forming ability of N-vinylformamide copolymer with 1-vinyl-3,5-dimethylpyrazole as applied to organic acids, was established. The applied extraction systems based on N-vinylformamide copolymers are characterized by environmental and economic feasibility, and good metrological parameters. The calculated quantitative characteristics of the extraction of sorbic acid allow using copolymers to extract and determine the analyte in the presence of other components of the matrix.

Keywords

• sorbic acid
• extraction
• water-soluble copolymer
• electrophoretic determination.