Interference and Its Elimination in Determination of Germanium and Cadmium in Geological Samples by Inductively Coupled Plasma-Mass Spectrometry

The samples were decomposed by mixed acid of HF-HClO4-HNO3. Germanium and cadmium in sample solutions were determined by inductively coupled plasmamass spectrometry with external calibration method. 74Ge and 114Cd were chosen as determining isotopes and 103Rh as internal standard. The instrument operating parameters were optimized and the interference from coexistent elements of Zn, Zr, Sn, Ce, Nd, Sm to the determination of Ge and Cd was studied. Interference from Nd2+and Sm2+ to Ge and from Sn isobars to Cd were calibrated by the mathematical method. The detection limits (10SD） of method for Ge and Cd are 30 ng/L and 15 ng/L respectively. The method has been verified by the determination of Cd and Ge in geological standard reference materials and the results are in agreement with certified values with precision of 1.35％RSD for Ge and 1.47％RSD for Cd. The method is suitable for the determination of trace Ge and Cd in geological samples.