Recent advances in chromium speciation in biological samples

The chromium toxicity greatly depends on its oxidation state and therefore accurate determination of all Cr species is essential to understand its potential health risk. Numerous critical reviews have underlined the exposure to especially Cr(III) and Cr(VI) species in various matrices but the chromium speciation in biological samples has not been discussed yet. Therefore, the objective of this article is to review recent advances in chromium speciation in various biological samples. Up to now, the most widely studied biological samples are urine, whole blood, serum, plasma but few studies dealing with tissues, saliva and joint effusion have been published as well. The major emphasis is put on the sampling, different pre-treatment procedures, and application of off-line and on-line techniques based on different atomic spectrometry methods together with their validation. A partial attention has been paid on the diversity of Cr species in biological samples as well as their interconversions together with the suggested speciated isotope dilution (SID) approach representing a valuable tool for correction of these interconversions.