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Characterization of selenoamino acids and other related selenium compounds of medical and nutritional importance
Increasing speciation demands in clinical chemistry, toxicology and nutrition have made the determination of the total elements in a sample inadequate; the amount of an element and the chemical forms in which it is present need to be known. Inductively coupled plasma mass spectrometry (ICP-MS) was used after high performance liquid chromatographic (HPLC) separation, as was electrospray ionization mass spectrometry (ESI-MS) for the characterization of selenium compounds. Consumption of selenium enriched plants or yeast-based nutritional supplements has been reported to provide anticarcinogenic benefits which are selenium compound dependent. Separation and identification of these selenium compounds is critical to understand the activity. Plants and yeast convert inorganic selenium in the soil or growth media into organoselenium compounds, probably following a route similar to the sulfur assimilatory pathway. Non-volatile selenium compounds produced include selenoamino acids, some of which have shown anticarcinogenic activity. A series of ion-pair chromatographic methods with ICP-MS and ESI-MS detection for the separation, qualitative and quantitative determination of non-volatile selenium compounds extracted from different samples has been developed. The method also provides the capability of determining the presence of selenoxides. Results of total selenium determination and speciation of selenium enriched yeast-based nutritional supplements, selenium-enriched Allium vegetables and phytoremediation samples are presented. More than 75% of the total eluting compounds were identified from retention time data and standard spiking experiments, and between 60 and 85% of compounds were identified by MS. Mass spectral behavior of selenoamino acids, using electrospray and ion trap technology with direct infusion and liquid chromatographic sample introduction, is also reported.
Kotrebai, Mihaly, "Characterization of selenoamino acids and other related selenium compounds of medical and nutritional importance" (2000). Doctoral Dissertations Available from Proquest. AAI9960765.