Speciation analysis of selenium metabolites in yeast-based food supplements by ICPMS-assisted hydrophilic interaction HPLC-hybrid linear ion trap/Orbitrap MS(n).

A new method was proposed for speciation analysis for selenium metabolites in Se-rich yeast. The coupling of a normal bore (4.6 mm) hydrophilic interaction liquid chromatography (HILIC) column with a hybrid linear ion trap/orbital ion trap mass spectrometer allowed the detection of the selenium-isotopic pattern in mass spectra down to the intrascan abundance of 0.001 with the low- and sub-part per million (ppm) mass accuracy regardless of the concentration. The quantitative elution recovery was verified by online ICPMS. The confirmation that all the species present were found was achieved by the parallel use of anion-exchange HPLC-ICPMS optimized for the maximum resolution. The species with intrascan abundance of at least 0.005 produced a cascade of product ion mass spectra to at least MS (4) with the preservation of the selenium isotopic pattern and the sub-ppm mass accuracy, which largely facilitated the structure elucidation. The approach was successfully applied to the characterization of nine (all which were present in the analyzed sample) selenium species in one chromatographic run.