ANALYTICAL SELENOAMINO ACID STUDIES BY CHROMATOGRAPHY WITH INTERFACEDATOMIC MASS-SPECTROMETRY AND ATOMIC-EMISSION SPECTRAL DETECTION

Consumption of selenium enriched plants or yeast-based nutritional sup plements has been reported to provide anticarcinogenic benefits which are selenium compound dependent. Separation and identification of thes e selenium compounds is critical to understand the activity. Plants an d yeast convert inorganic selenium in the soil or growth media into or ganoselenium compounds, probably following a route similar to the sulf ur assimilatory pathway. Non-volatile selenium compounds produced incl ude selenoamino acids, some of which have shown anticarcinogenic activ ity. Volatile compounds produced by chemical reaction of involatile pr ecursors have also been found. An ion pair chromatographic method with ICP-MS detection for the separation of selenoamino acid standards pot entially present in real samples is given. The method allows separatio n of selenoamino acids including such analytes as the cis-trans isomer s of Se-1-propenyl-DL-selenocysteine. The method also provides the cap ability of determining the presence of selenoxides and possibly seleno nes, and tracking of other functionalities and reactions by selective derivatization. Alternatively, selenoamino acids are treated with ethy lchloroformate to produce stable volatile derivatives which are amenab le to GC separation with element specific atomic emission detection (G C-AED). Results of total selenium determination and speciation of sele nium enriched yeast-based nutritional supplements, selenium enriched a llium vegetables and bioremediation samples are presented.