Determination of trace cadmium in geological samples by membrane desolvation inductively coupled plasma mass spectrometry

Abstract

The accurate determination of Cd in geological samples by inductively coupled plasma mass spectrometry (ICP-MS) suffers significant interference from polyatomic ions especially the oxides and hydroxides of Mo and Zr. In this study, we coupled membrane desolvation system with ICP-MS to reduce Mo and Zr based interference and accurately measured Cd content in geological samples. With the solvent in samples solution were removed by membrane desolvation system, Zr based interferences were reduced to blank level and Mo based interferences were reduced by about 10 times. In addition, the membrane desolvation sample introduction system also increased the Cd sensitivity 13 times compared to conventional pneumatic nebulizer with spray chamber. Under the optimal conditions, a linear working curve is obtained at least for Cd concentrations of 0.1–10 μg/L, with a correlation coefficient of 0.9999 and detection limit is calculated to be 0.004 μg/L for Cd. The proposed method was demonstrated by analysis of 25 geological standard reference samples and the results showed that membrane desolvation significantly improved analytical accuracy for Cd by ICP-MS, especially for the low Cd samples.