Direct determination of trace germanium in river samples by CH4-Ar mixed gas plasma DRC-ICP-MS

Abstract

In this work, a reliable method based on CH4-Ar mixed gas plasma DRC-ICP-MS was developed for direct determination of trace Ge in river samples. The interfering polyatomic ions 36Ar2+, 56Fe16O+, 40Ar32S+, 40Ar16O2+, 55Mn16OH+ on 72Ge+ determination could be reduced by 68% using the DRC with CH4 as the reaction gas. In addition, the CH4 gas was introduced to the ICP plasma at 2mLmin−1, the signal intensity of 72Ge+ was increased by a factor of 3.3 and the background signal (at m/z 72) was decreased to 29.4%. The method’s signal to background ratio (SBR) was improved 11-fold (from 5 to 55). Under the optimized conditions, the limit of quantification (LOQ) was 0.012μgL−1, and the reproducibility (RSD) was generally less than 3%. The proposed method was applied for the determination of trace Ge in river samples, and the spiked recoveries was in the range of 95.0%–112%. The accuracy of determination results of proposed method was validated by that of standard addition method, and the determination results of two methods were in good agreement.