Sample preparation and HPLC separation approaches to speciation analysis of selenium in yeast by ICP-MS

• Published in: Journal of analytical atomic spectrometry 1999, Vol.14 (4), p.645-650
• Main Authors: CASIOT, C, SZPUNAR, J, ŁOBINSKI, R, POTIN-GAUTIER, M
• Format: Article
• Language: English
• Subjects: Analytical chemistry; Biological and medical sciences; Chemical Sciences; Fundamental and applied biological sciences. Psychology; Microbiology; Morphology, structure, chemical composition; Mycology
• ISSN: 0267-9477; 1364-5544
• DOI: 10.1039/a809027k

Eight solid-liquid extraction procedures were evaluated for the recovery of selenium species from yeast. Speciation of Se in the extracts was characterized by different types of HPLC, including size-exclusion, anion-exchange and reversed-phase chromatography with ICP-MS detection. The results obtained depended critically on the sample preparation procedure used. Leaching with water and with methanol led only to 10-20% recoveries of Se, split into eight compounds, among which Se(IV) and selenomethionine could be identified. Leaching with pectinolytic enzymes released an additional 20% of selenomethionine. Leaching with sodium dodecyl sulfate solution allowed the solubilization of a selenoprotein that accounted for ca. 30% of the total Se present. Leaching with proteolytic enzymes led to recoveries of Se above 85%, the majority as selenomethionine. Hydrolysis of the yeast with tetramethylammonium hydroxide solubilized the sample completely but the Se species present were entirely degraded to selenomethionine and inorganic selenium. A sequential leaching procedure is proposed for the evaluation of selenium speciation in yeast without the need for a coupled technique.