Precise selenium isotope ratios measurement using a multimode sample introduction system (MSIS) coupled with multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS)

Abstract

A multimode sample introduction hydride generation system (MSIS) was explored for rapid and precise measurements of Se isotope ratios. The MSIS system was modified in our laboratory in order to be coupled to the Neptune multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) instrument. The principle aim of this study was focused on the optimization of the MSIS operating parameters for the determination of precise Se isotopic ratios measurements in environmental samples using the MC-ICP-MS as a detection system. Special attention has been paid to the performance of the MSIS system in dual mode operation “simultaneous nebulization and vapour (hydride) generation”. Typical internal (within-run) precision achieved under optimal conditions was better than 33 ppm (1 RSE) for ⁷⁸Se/⁷⁶Se, ⁷⁸Se/⁷⁷Se, ⁷⁸Se/⁸⁰Se and ⁷⁸Se/⁸²Se ratios using repeated measurements of NIST SRM 3149 Se standard solution. On average, the short-term uncertainty was better than 200, 150, 481 and 90 ppm (1 RSD) for ⁷⁸Se/⁷⁶Se, ⁷⁸Se/⁷⁷Se, ⁷⁸Se/⁸⁰Se and ⁷⁸Se/⁸²Se isotope ratios, respectively.