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 CH 4 -Ar mixed gas plasma DRC-ICP-MS was developed for direct determination of trace Ge in river samples. The interfering polyatomic ions 36 Ar 2 + , 56 Fe 16 O + , 40 Ar 32 S + , 40 Ar 16 O 2 + , 55 Mn 16 OH + on 72 Ge + determination could be reduced by 68% using the DRC with CH 4 as the reaction gas. In addition, the CH 4 gas was introduced to the ICP plasma at 2 mL min −1 , the signal intensity of 72 Ge + 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 0.012 μg L −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.