Direct determination of cadmium in urine by electrothermal atomisation atomic absorption spectrometry

Abstract

Two direct methods for the measurement of cadmium in urine by electrothermal atomisation atomic absorption spectrometry are described and compared. In the first, standards and samples are diluted 1 + 4 with 6%V/V nitric acid and measured with a four-stage furnace programme using a L'vov platform in an uncoated graphite tube. Selective volatilisation is used to help separate the cadmium peak from the background absorbance peak. In the second, standards and samples are diluted 1 + 1 with 1%V/V nitric acid and analysed off the wall of an uncoated tube with a short three-stage programme using no ashing stage. Both methods show satisfactory recovery and good correlation with a solvent extraction method confirming that interferences have been successfully overcome by the use of nitric acid as a modifier. The platform method has a cycle time of 129 s while the tube-wall method achieves analysis with a cycle time of only 50 s.