Cr speciation analysis based on electrokinetic sample pretreatment with a paper based analytical device

This work presents a new method of Cr speciation analysis based on micro sample pretreatment with a paper-based analytical device (PAD). By using electrokinetic separation and stacking on the PAD, Cr (VI) and Cr (III) can be separated and the recovered to achieve speciation analysis without have to be subjected to subtraction treatment. The separation and recovery properties of Cr (VI) and Cr (III) were characterized and optimized by UV–Vis spectrophotometry , with which the LOQ of 19.0 μg L −1 and 28.7 μg L −1 , and the recoveries of 88–108% and 90–110%, were obtained for Cr (VI) and Cr (III), respectively. In addition, direct analysis of Cr (VI)/Cr (III) from an electroplating wastewater sample was also demonstrated with this method combined with atomic spectroscopy (GF-AAS and ICP-OES). This sample pretreatment method is fast, cheap and easy to be used. Combined with the high sensitivity and elemental selectivity of atomic spectroscopy and mass spectrometry, this PAD sample pretreatment method could be a compensation to their lack in speciation discrimination, and may play an important role in the speciation analysis of Cr.