Flameless Atomic-Absorption Spectrometric and Differential-Pulse Polarographic Determination of Cadmium after Coprecipitation with Hafnium Hydroxide

Abstract

Abstract Using the coprecipitation method with hafnium hydroxide, the flameless atomic-absorption spectrometric and the differential-pulse polarographic determinations of cadmium have been studied. The collecting ability of hafnium hydroxide for cadmium is excellent; from 0.01 to at least 1000 μg of cadmium in 50–400 cm3 of a sample solution is coprecipitated quantitatively. The presence of hafnium hydroxide does not interfere with either method of determining cadmium. Of the diverse ions examined, there are no ions which interfere with the flameless atomic-absorption spectrometric determination, even if they are present in a concentration of at least 5000 times that of cadmium; as for the differential-pulse polarographic determination, only indium interferes when present in small amounts. The linear calibration curves through the point of origin were obtained over the range of 0.4–4 ng cm−3 of cadmium for the former method and 0.04–40 μg cm−3 for the latter method. In the proposed methods, the flameless atomic-absorption spectrometric determination was successfully applied to the analysis for trace amounts of cadmium in river-water samples.