Chromium redox speciation in food samples

Chromium is an element with important biological characteristics, depending on its different species. Cr(III) is considered as essential; however, the Cr(VI) form is classified as carcinogenic. For this reason, speciation analysis in food samples is a very important question. The proposed data procedures for chromium redox speciation in the literature can be divided into those with the use of online hyphenated techniques and those where appropriate sample pretreatment is necessary. The strategies for nonchromatographic speciation are mainly based on selective liquid liquid extraction procedures, coprecipitation, selective separation of chromium species using a solid phase extraction column, or complexation reactions. In this paper, the application of these strategies for determination of Cr(III) and Cr(VI) contents in common food samples (water, milk, tea infusion, bread, and beer) are presented and discussed. This survey is an attempt to cover the state of the art since 2012.