Simultaneous determination of Cr (III) and Cr (VI) in functional foods using liquid chromatography - inductively coupled plasma mass spectrometry (LC-ICP-MS)

Abstract

Chromium is often added in some functional foods to aid in the treatment of diabetes or in fortified dairy products. The toxicity of chromium depends on the oxidation state. Therefore, it is necessary to identify or quantify chromium species to assess food safety hazards. In this study, the species of Cr (III) and Cr (VI) were determined by liquid chromatography (LC) with collision cell inductively coupled plasma mass spectrometry (ICP-MS). The main parameters such as the concentration of complexing agents, the effect of pH, the mobile phase flow rate, the extraction solvents as well as the extraction time and temperature were optimized. The method detection limits (MDLs) of 20 µg/kg for Cr (III) and 10 µg/kg for Cr (VI) obtained based on peak hight at mass 52 for injections at low level spiked samples. The repeatability of Cr (III) was 1.96 % while that of Cr (VI) was 7.78%. The recovery of Cr (III) and Cr (VI) at 1 mg/kg was in the range of 91.3 - 98.4% and 89.3 - 96.7% respectively. The validated parameters were completely meeting the Association of Official Analytical Collaboration (AOAC) performance requirements, which was applied to analyze Cr species in some functional food samples collected on the market. The content of Cr (III) was found in accordance with products label declaration while Cr (VI) was not detected.