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.
