Internal standardization using a dual mode sample introduction system in the determination of As by HG-ICP-MS

• A dual mode system was used to introduce internal standards simultaneously as hydrides and via solution nebulization in the determination of As by ICP-MS technique
• Y and Pd were introduced by solution nebulization and Ge and Bi as hydrides
• The use of Y and Pd as internal standards resulted in accurate results

Internal standardization was studied by introducing internal standards simultaneously by liquid nebulization (Y, Pd) and hydride generation (Ge, Bi) with a dual mode sample introduction system in the determination of arsenic by HG-ICP-MS. The effects of the gas flow rates and ICP-MS parameters were examined for all the elements. Sample introduction for Ge and Bi is similar to arsenic and therefore they could correct the signal variations originating from the hydride generation sample introduction system. The results indicated, that in addition to hydride forming internal standards, the signal variations caused by the changes in the main plasma conditions can be corrected by using aqueous internal standards introduced by solution nebulization. The accuracy of the measurements were studied by analyzing two different certified reference materials (ERM-CA615 and NIST 1573a) and the results were in good agreement with the certified values. However, it was found out, that the Bi was not suitable hydride forming internal standard for the real samples because it can occur in the samples in small concentrations and the formed hydride is instable.