Electrothermal Atomic Absorption Spectrometric Determination of Cadmium after Coprecipitation with Nickel Diethyldithiocarbamate

Abstract

Nickel diethyldithiocarbamate (nickel DDTC) coprecipitated quantitatively 3 - 90 ng of cadmium in up to 500 cm³ of the sample solution at pH 4.0 - 11.5. The coprecipitant could be easily dissolved with nitric acid (1+1) and acetone, and 3 - 90 ng of cadmium in the final solution (10 cm³) could be determined by electrothermal atomic absorption spectrometry. The peak height of cadmium in atomic absorbance measurements remained almost constant, even if large amounts of nickel DDTC (up to at least 10 mg as nickel amount) were used for the coprecipitation. The detection limit (signal/noise=2) was 1.2 pg cm^-3 of cadmium in 500 cm³ of the initial sample solution. The 32 diverse ions investigated did not interfere with the determination in at least a 1000-fold mass ratio to cadmium. The proposed method was successfully applied to the determination of trace amounts of cadmium in river and sea water.