Abstract

A detailed comparison of the performance of different nebulisation (Meinhard, hydraulic high pressure and microconcentric nebulisers) and chromatographic (reversed-phase and ion-pair) systems for the speciation of selenium by hexapole collision and reaction cell inductively coupled plasma mass spectrometry (ICP-MS) was carried out. The relative limits of detection for the seleno compounds under study (selenite, selenate, selenocystine, selenomethionine and selenoethionine) monitoring isotope ⁸⁰Se were in the range 100–200 pg mL⁻¹ (Meinhard nebuliser), 80–150 pg mL⁻¹ (microconcentric nebuliser) and 35–90 pg mL⁻¹ (hydraulic high pressure nebuliser). Selenium species separation was carried out by both reversed-phase and ion-pair high-performance liquid chromatography (HPLC). More seleno compounds could be separated and a slight improvement in the limits of detection was obtained with the ion-pair HPLC system. Different commercial nutritional selenium supplements were analysed by both chromatographic techniques after extraction with hot water. The efficiency of this extraction was in the range 80–95% for selenate and selenomethionine and 10–25% for selenoyeast-based supplements. Identification of some seleno compounds and quantification in supplement samples were easily and rapidly realised with the MassLynx^™ software.