ВОЛЬТАМПЕРОМЕТРИЧЕСКОЕ ОПРЕДЕЛЕНИЕ КАРМУАЗИНА В НАПИТКАХ С ИСПОЛЬЗОВАНИЕМ ЭЛЕКТРОДОВ, МОДИФИЦИРОВАННЫХ ПАВ

Abstract

The results of the study of electrochemical reduction of the food azo dye carmoisine (E122) on a glass-carbon electrode modified with cationic surfactant cetyltrimethylammonium bromide (CTAB) are presented. Due to electrostatic interaction between negatively charged sulfo-groups of the dye and positively charged groups of CTAB fixed on the electrode surface, adsorption concentration of the dye occurs, which significantly increases its reduction current compared to the unmodified electrode. The electroactive group of carmoisine is the azo group, which is irreversibly reduced to the hydrazo group: -N=N- + 2H++ 2e- → -NH-NH-. Optimal conditions for the determination of carmoisine by linear and cyclic voltammetry methods have been determined by studying the effect of the potential and time of pre-concentration, the acidity of the medium, and the rate of potential sweep on the parameters of voltammograms. It is shown that with an increase in the acidity of the medium, a shift in the peak of carmoisine reduction is observed -530 mV (vs. Ag/AgCl) (pH 8) to -220 mV (vs. Ag/AgCl) (pH 2), and the maximum amplitude of the current is observed at pH 5-7. The reduction current increases with increasing accumulation time (the optimal time is 60 s) and does not depend on the accumulation potential (the optimal potential is 0 V). The study of the effect of the potential sweep rate (5-320 mV/s) on the reduction current indicates the diffusive nature of it. The dependence of the peak current on the concentration of carmoisine is linear in the range of 0.2 - 2.0 mg/dm3 (detection limit 0.1 mg/dm3). The analysis of carmoisine is not hindered by the presence of another azo dye in the solution - Sunset Yellow E110 (SY). The developed method of voltammetric determination was tested and compared with the spectrophotometric method using the example of the analysis of several drinks containing carmoisine, as well as its mixture with SY.