Electrochemical Oxidation of l-selenomethionine and Se-methylseleno-l-cysteine at a Thiol-Compound-Modified Gold Electrode: Its Application in a Flow-Through Voltammetric Sensor

Abstract

A flow-electrolytic cell that consists of a bare gold wire or of different thiol-compound-modified gold electrodes (such as 2,4-thiazolidinedione, 2-mercapto-5-thiazoline, 2-mercaptothiazoline, l-cysteine, thioglycolic acid) was designed to be used in a voltammetric detector to identify l-selenomethionine and Se-methylseleno-l-cysteine using high-performance liquid chromatography. Both l-selenomethionine and Se-methylseleno-l-cysteine are more efficiently electrochemically oxidized on a thiol/gold than on a bare gold electrode. For the DC mode, and for measurements with suitable experimental parameters, a linear concentration from 10 to 1600 ng·mL−1 was found. The limits of quantification for l-selenomethionine and Se-methylseleno-l-cysteine were below 10 ng·mL−1. The method can be applied to the quantitative determination of l-selenomethionine and Se-methylseleno-l-cysteine in commercial selenium-containing supplement products. Findings using high-performance liquid chromatography with a flow-through voltammetric detector and ultraviolet detector are comparable.

Keywords

• thiol-modified gold electrodes
• amperometric detection
• l-selenomethionine%22%2C%22default_operator%22%3A%22AND%22%7D%7D%7D"> ">l-selenomethionine
• Se-methylseleno-
• l-cysteine%22%2C%22default_operator%22%3A%22AND%22%7D%7D%7D"> ">l-cysteine