Determination of silver, tin and tungsten in geochemical sample by inductively coupled plasma mass spectrometry with high-pressure closed digestion

In the analysis of geochemical samples, traditional methods for determining silver (Ag), tin (Sn), and tungsten (W) often face challenges such as time-consuming sample treatment, complex operational procedures, and high requirements for operators’ technical proficiency and specialized knowledge. In this study, samples were digested using a high-pressure closed system with a hydrofluoric acid-nitric acid mixture, followed by the simultaneous determination of Ag, Sn, and W contents using inductively coupled plasma mass spectrometry (ICP-MS). Various digestion systems were investigated. Spectral and non-spectral interferences with the analytical isotopes of the target elements were systematically evaluated. The dilution technique and internal standard method were employed to effectively mitigate non-spectral interferences. Meanwhile, spectral interferences were successfully eliminated using the kinetic energy discrimination (KED) mode and online interference correction equations. The performance of the method was evaluated using certified reference materials (CRMs) of soil, stream sediment, and rock. The results demonstrated that the limits of detection for Ag, Sn, and W ranged from 0.016 to 0.24 μg/g. The relative errors (RE) between the measured and certified values were 0.43% to 8.33%, the logarithmic deviations (Δlg) were 0.003 to 0.035, and the relative standard deviations (RSD,n=6) were 2.0% to 7.6%. The method meets the determination requirements of the multi-objective regional geochemical survey specification (1∶250 000). It achieves simultaneous determination of multiple elements from a single digestion, significantly improving the work efficiency.