Determination of chromium(VI)and chromium(III)in river water by flame atomic absorption spectrometry

Chromium(Ⅵ)can react with diphenylcarbazide(DPC)in perchloric acidic medium to form the complex of chromium(Ⅵ)-DPC which can be extracted with n-pentanol.This was used for the determination of trace chromium(Ⅵ)and chromium(Ⅲ)in river water by flame atomic absorption spectrometry.KMnO_4 was used as the oxidant for the oxidation of chromium(Ⅲ)to chromium(Ⅵ)which was then determined by the same way.The limit of detection was 0.0007 mg·L~(-1)and Beer's law was obeyed in a wide linear dynamic range of 0.0007～1.0 mg·L~(-1)chromium(Ⅵ).The recovery of chromium(Ⅵ)and chromium(Ⅲ)was 100%～112%and 89%～104%,respectively.