Determination of germanium in environmental samples by electrothermal atomic absorption spectrometry with continuous flow hydride generation in dilute perchloric acid solution

Abstract

A method has been developed for the sensitive determination of germanium by continuous flow hydride generation electrothermal atomic absorption spectrometry with trapping in a graphite atomizer pretreated with palladium. The optimal acidities using different acids for the generation of germanium hydride were studied. Germanium was found to give a sharp analytical signal in 0.05 mol l^–1 H₂SO₄, 0.15 mol l^–1 HNO₃, and 0.10–0.15 mol l^–1 HCl. Beyond these optimal acidities, significant loss of sensitivity resulted. Among the acids investigated only perchloric acid provided a wider range of acidity (0.15–0.6 mol l^–1) giving maximum efficiency for the production of germanium hydride. Interferences from Ni, Cu, Fe, Mn and Sn on the generation of the hydride from 0.5 mol l^–1 HClO₄ were minimized by the addition of 0.1% EDTA. The characteristic mass which gave an integrated absorbance of 0.0044 s was found to be 46 pg. An absolute detection limit (3s) of 36 pg was obtained. The method was applied successfully in the determination of germanium in coal fly ash, soil and river sediments following the decomposition of the samples by heating in a mixture of acids using a pressure bomb.