Selective Voltammetric Determination of Sulfur-Containing Amino Acids in Drugs and Vitamin Complexes on an Electrode Modified by a Ruthenium-Hexachloroplatinate Film

Abstract

An inorganic film of ruthenium hexachloroplatinate (RuPtCl₆) deposited on the surface of a glassy-carbon electrode exhibited catalytic activity for oxidation of S-containing amino acids. Catalytic electrochemical oxidation of cysteine, cystine, and methionine occurred at various potentials. The optimum conditions for producing a RuPtCl₆ film that gave the greatest catalytic effect were found. A method for selective voltammetric determination of cysteine, methionine, and cystine at an RuPtCl₆-film electrode was developed. The lower limit of quantitation of cysteine and cystine was 5 × 10^–6 M; of methionine, 5 × 10^–7 M. The proposed voltammetric method was used to determine cysteine, cystine, and methionine in drugs and vitamin complexes.