Elimination of Interferences in ICP-MS Determination of Sc, Ga, Ge, In, Cd and Tl in Geological Samples

Geological sample was decomposed with a mixed acid of nitric acid, hydrofluoric acid and perchloric acid under hermetic condition. The salt content of the sample solution was carefully controlled by appropriate dilution with value of DF of 1 000. Elimination of matrix and physical effects were attained by correction with Rh and Ir as internal standards. Interferences of 28Si16O1H and 29Si16O on the determination of 45Sc were eliminated by removal of Si in sample pre-treatment. Furthermore, some other interferences, such as 142Ce2+ and 142Nd2+ on the determination of 71Ga, 58Ni16O, 148Sm2+ and 148Nd2+ on the determination of 74Ge, 114Sn, 98Mo16O and 97Mo16O1H on the determination of 114Cd, 115Sn, 98Mo16O1H and 98Mo17O on the determination of 115In, were eliminated by mathematical corrections. The interferences of 204Pb and 206Pb (with high concentration) on the determination of 203Tl and 205Tl were eliminated by separation with precipitation of Pb from the sample solution in the pre-treatment. The proposed method was tested by analyzing a CRM for its corrtents of Sc, Ga, Ge, In, Cd and Tl, giving results in consistency with the certified values.