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.KMnO4 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-1and Beer’s law was obeyed in a wide linear dynamic range of 0.0007～1.0 mg·L-1chromium（Ⅵ）.The recovery of chromium（Ⅵ）and chromium（Ⅲ）was 100%～112%and 89%～104%,respectively.
