Optimisation of selective alkaline extraction for Cr(VI) determination in dairy and cereal products by HPIC-ICPMS using an experimental design

This study presents the optimisation through an experimental design then the validation of a method to determine Cr(VI) in certain foodstuffs by high-performance ionic chromatography with inductively coupled plasma mass spectrometry. This method is free from interferences possibly associated with chloride and organic or inorganic carbon. Analytical performances assessed by the accuracy profile method were satisfactory in terms of linearity, specificity, sensitivity, accuracy, repeatability and intermediate precision. Limits of quantification ranged from 0.6 μg.kg−1 in dairy products to 0.8 μg.kg−1 in cereal products. The method was applied to the determination of Cr(VI) in dairy and cereal products from different brands and origins. Despite the method's very high sensitivity, Cr(VI) was not found in all the studied samples. This confirms the results of the most recent studies using an on-line speciation method, and invalidates older studies that found traces of Cr(VI) in food by using a less specific off-line speciation method.