Interference removal for cadmium determination in waste water and sewage sludge by flow injection cold vapour generation atomic absorption spectrometry

Abstract

Cold vapour generation coupled to atomic absorption spectrometry with using flow injection (FI-CVAAS) was evaluated as a rapid and simple method for the determination of cadmium in waste water and sewage sludge. Waste water samples did not need a pre-treatment before analysis. The sewage sludge was digested in a high pressure microwave oven in order to ensure good solubilisation of the samples. Some elements present in the sample (Cu, Pb, Ni, Zn) showed important interferences in the FI-CVAAS method. Elimination of such interferences by adding KCN to the borohydride solution is discussed. Validation of the method was achieved by analysing a sewage sludge sample used in an interlaboratory exercise organised by the WRC (Water Research Centre, UK) and by comparing the results with those obtained by electrothermal atomic absorption spectrometry (ETAAS) by use of a graphite furnace. Finally, waste waters and sewage sludge samples were analysed by both FI-CVAAS and ETAAS methods.