Speciation analysis of chromium by ion exchange separation with flame atomic absorption sepectrometry

Speciation of chromium in environmental water samples was determined by flame atomic absorption spectrometry(FAAS). Chromium(Ⅵ) was separated from chromium(Ⅲ) and other ions with anion-exchange resin,then chromium(Ⅵ) was reduced and eluted by the mixture of ascorbic acid and sulphuric acid. The effects of separate conditions,such as the pH of the test solutions,conditions of washing and elution,etc. are discussed. The results show that,under the optimum conditions,the RSD of the method is 1.2% for chromium(Ⅵ) and 1.9% for chromium(Ⅲ),the rate of recovery is 98% for chromium(Ⅵ) and chromium(Ⅲ) all. The limit of detection of the method is 0.6 μg/L.