[Speciation analysis of chromium(VI) and chromium(III) in water sample using flame atomic absorption spectrometry with TOA-benzene extraction separation system].

A rapid and sensitive method for the sequential determination of Cr(VI) and Cr(III) in water samples based on flame atomic absorption spectrometry with TOA-benzene extraction separation system has been developed. In the H2SO4 medium. Cr(VI) in sample solution was extracted into the organic phase by using the TOA-Benzene and Cr(III) remained in the water phase. Cr(VI) in the organic phase and Cr(III) in the water phase were determined separately by AAS. This method is simple, fast and of microscale. The results obtained by this method agreed well with those obtained by conventional method. The recoveries are 95.0%-102% for Cr(VI) and 94.8-103% for Cr(III). The relative standard deviations were 2.9% for Cr(VI) and 2.6% for Cr(Ill). The system has enrichment effect for Cr(VI), and the detection limits are 6.6 microg x L(-1) for Cr(VI) and 0.20 mg x L(-1) for Cr(III). The maximum extracted amount of Cr(VI) by TOA was 4.6 mg x mL(-1).