Selenoamino acid speciation using HPLC–ETAAS following an enzymic hydrolysis of selenoprotein

A high-pressure liquid chromatography-electrothermal atomic absorption spectroscopy (HPLC-ETAAS) hyphenated technique was used for the determination of seleno compounds present in a selenium-enriched yeast. Conditions were optimized for the separation and quantification of the selenoamino acids, selenocystine and selenomethionine, in the presence of other compounds. The separation was achieved by ion-pairing chromatography using sodium heptanesulphonate as the anionic counterion. On-line detection was carried out using electrothermal atomic absorption with palladium(II) as a matrix modifier. Different extraction procedures were tested on a selenium-enriched yeast. A 92% recovery of the total selenium present in the material was obtained. Attempts to evaluate selenium speciation were carried out ; selenomethionine and selenocystine were identified as the major components (42% and 35% respectively).