Interference Correction in Determination of Cu, Zn, Eu, Gd, Tb in Geological Samples by Inductively Coupled Plasma-Mass Spectrometry

Since Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) detection is not in a closed vacuum system, ions generated from gas, water and acid may enter the detection system in the test procedures, resulting in interference, which affects accurate analysis for trace elements. Geological samples were decomposed by pressurized acid digestion of HF-HNO₃, and Cu, Zn, Eu, Gd and Tb were simultaneously determined by ICP-MS. The instrument operating parameters were optimized and the interferences from the coexisting elements of Ti, Ba, Ce, Pr, Nd for the determination of Cu, Zn, Eu, Gd, Tb were studied. The interference correction of oxide interferences for the elements Ti, Ba, Ce, Pr and Nd was performed with interference coefficients by mathematical method, which improved the accuracy for Cu, Zn, Eu, Gd, Tb determination in geological samples. Interference coefficients of Cu, Zn, Eu, Gd and Tb were calibrated by determining similar concentrations of the interference elements Ti, Ba, Ce, Pr, Nd. The detection limits (10SD) for Cu, Zn, Eu, Gd and Tb were 0.47, 0.82, 0.002, 0.004 and 0.002 μg/g, respectively. Both the accuracy and precision of the method were validated by analyzing standard reference materials GBW 07104, GBW 07105, GBW 07123, GBW 07303, GBW 07311, GBW 07402 and GBW 07404 with RSD (n=12) less than 5.0% and RE (n=12) less than 5.0%. The results were in good agreement with the certified values of the national standard materials of rock, soil and stream sediments. The method has been successfully used in practice for Cu, Zn, Eu, Gd and Tb determination in geological samples.