Determination of the selenium isotopic compositions in Se-rich yeast by hydride generation-inductively coupled plasma multicollector mass spectrometry

Abstract

A method was developed for the precise determination of selenium isotopic compositions (δ^82/77Se, δ^82/76Se and δ^82/74Se) by hydride generation inductively coupled plasma multiple collector mass spectrometry (HG-MC ICP MS) in Se-rich yeast. The conversion of all the selenium forms into Se(IV) during digestion and reduction steps was investigated by anion-exchange ICP quadrupole MS (SAX ICP Q MS) and was found to be complete. Measurement precision values expressed as deltas (δ) with regard to NIST SRM3149 were between 0.2–0.4‰ (2SD) over a period of 6 months for 25 or 50 ng mL⁻¹ of introduced selenium. The application of the method to the analysis of nine Se-rich yeast supplements from different manufactures showed significant variations in the isotope ratios suggesting that the latter can be an attractive parameter for the yeast provenance discrimination.