Enantioselective Voltammetric Sensors Based on Amino Acid Complexes of Cu(II), Co(III), and Zn(II)
R. A. Zilberg, Л. Р. Загитова, И. В. Вакулин, Yu. A. Yarkaeva, Yu. B. Teres, Т. В. Берестова
Abstract
The electrochemical and analytical characteristics of enantioselective sensors based on glassy carbon electrodes modified by chelate complexes (bis(L-phenylalaninate) copper(II), glycinato-L-phenylalaninate copper(II), tris(L-phenylalaninate) cobalt(II), bis(L-phenylalaninate) zinc) are studied. It is found that the most promising sensor for determining tryptophan enantiomers is the sensor modified by copper(II) (bis)L-phenylalaninate. In determining tryptophan enantiomers, this sensor provides a linear concentration range from 6.25 × 10–7 to 0.5 × 10–3 M for L-tryptophan and from 5 × 10–6 to 0.5 × 10–3 M for D-tryptophan. The sensor is more sensitive to L-tryptophan. The proposed sensor was used for the recognition and determination of tryptophan enantiomers in human urine and plasma samples, and also in a mixture of enantiomers. The statistical assessment of the results of determinations by the spiked–found method indicates the absence of a significant systematic error.