Determination of total selenium and seleno-amino acids in yeast and aquatic organisms by liquid chromatography and inductively coupled plasma mass spectrometry

Abstract

The primary goal of this dissertation research was to develop methods for routine speciation analysis of selenium in tissues. A method for total selenium using on-line stable isotope dilution analysis with conventional ICP-MS (SIDA-ICP-MS) was developed. Masses at 77, 78, 79, 81, and 82 were monitored and quantitation of Se was determined based on both 78Se and 82Se. SIDA-ICP-MS was successfully applied to the determination of total selenium in biological materials, such as selenized yeasts, certified reference materials, lab-cultured oligochaetes and desert pupfish. The separation and quantitation of seleno-amino acids was accomplished by ion-pairing reversed-phase liquid chromatography (RPLC) and detected by ICP-MS at mass 82 using the standard mode. It was found that methanesulfonic acidic hydrolysis demonstrated a higher extraction efficiency of selenomethionine than enzymatic digestion. Selenomethionine (SeMet) was the only significant Se-containing species detected in the biological samples that were examined.