Determination of chromium picolinate and trace hexavalent chromium in multivitamins and supplements by HPLC-ICP-QQQ-MS

Chromium picolinate (CrPic) and trace hexavalent chromium (Cr(VI)) content were characterized in VITA-1 and VITB-1, two new multivitamin and mineral supplement candidate reference materials from National Research Council Canada, by two methods of high performance liquid chromatography inductively-coupled plasma triple quadrupole mass spectrometry. The conditions for the separation of Cr(VI) from EDTA-complexed Cr(III) were optimized such that species interconversions were not observed during analysis. Following extraction with dilute NH₄OH in water at pH 10 (for Cr(VI)) or 3:2 acetonitrile:water (for CrPic) and quantification by standard addition, it was concluded that CrPic accounted for 95–96 % of the Cr in VITA-1 and VITB-1, while Cr(VI) was not present above the detection limit of 0.13 μg Cr g⁻¹. Using the two developed methodologies, commercially-available nutritional supplements, in the form of vitamin tablets and dried food supplements, were assessed, and it was determined that CrPic accounted for the majority (92 %–98 %) of the chromium present in the tablets, and that Cr(VI) concentrations were below the detection limit for all samples except for the powdered beets where it accounted for nearly half of the total Cr present.