Speciation of chromium in waste water using ion chromatography inductively coupled plasma mass spectrometry

Ion chromatography (IC) coupled with inductively coupled plasma mass spectrometry (ICP–MS) was systematically investigated for determining the speciation of chromium in environmental samples. Firstly, the stability of complexes formed by Cr(III) with various aminopolycarboxylic acids was studied by electrospray ionization mass spectrometry (ESI–MS). The results showed that [Cr(EDTA)]− was stable in solution. Secondly, various mobile phases were examined to separate Cl− from chromium species by IC to avoid Cl− interference. The separation of [Cr(EDTA)]− and Cr(VI) was achieved on a new anion-exchange column (G3154A/102) using a mobile phase containing 20 mM NH4NO3 and 10 mM NH4H2PO4 at pH 7.0 without Cl− interference. Detection limits for chromium species were below 0.2 μg/L with a direct injection of sample and without prior removal of interferences from the matrix. Finally, the proposed method was used for the determination of chromium species in contaminated waters.