Determination of Selenium Concentrations in NIST SRM 610, 612, 614 and Reference Materials using the Electron Probe, LA-ICP-MS and SHRIMP II

Frances E Jenner, Peter Holden, John A. Mavrogenes,
Hugh St.C. O'Neill and Charlotte M. Allen

Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia

Selenium (Se) is a trace element with distinctive geochemical properties, which have yet to be exploited in petrology because of the analytical difficulties associated with its low concentrations in geological materials. Selenium (Se) has 6 naturally occurring stable isotopes; ⁷⁴Se, ⁷⁶Se, ⁷⁷Se, ⁷⁸Se, ⁸⁰Se and ⁸²Se and is both volatile and strongly siderophile. Constraining the range of Se concentrations in mantle-derived rocks is important to studies of planetary differentiation, partial melting models and recycling of lithospheric components into the mantle.

The abundance of Se in the mantle is not well known, but has been estimated to be 79 ppb by assuming chondritic Se/S (Palme and O'Neill 2003). Due to the time-consuming and often complicated sample preparation techniques used by previous studies (see Johnson and Bullen 2004 for a comprehensive review) and the high levels of analytical sensitivity required, little is known about the behaviour of Se in igneous systems.

In situ analysis of geological materials such as natural volcanic glasses and minerals, using LA-ICP-MS, allows the rapid measurement of major and trace element data for a wide range of elements that are below the detection limits of the electron microprobe (EMP). The quantification of LA-ICP-MS data of unknown samples is dependent on the analysis of calibration materials, such as NIST SRM 610 and 612. Currently, no published value is available for the concentration of Se in NIST SRM 612. We have used a combination of EMP, Sensitive High Resolution Ion Microprobe II (SHRIMP) and/or LA-ICP-MS techniques to measure the concentration of Selenium (Se) in NIST SRM 610, 612, 614 and a range of reference materials. The new reference value for Se in NIST 612 was then to measure the concentrations of Se in natural volcanic glasses.

Johnson, T. M., Bullen, T. D. (2004). Mass-Dependant Fractionation of Selenium and Chromium Isotopes in Low-Temperature Environments. In: Johnson, C. M., Beard, B. L., Albaréde, F. (Editors), Geochemistry of non-traditional stable isotopes. Reviews in Mineralogy and Geochemistry. Mineralogical Society of America, pp 289-317.

Palme, H, O'Neill, H. St.C. (2003). Cosmochemical Estimates of Mantle Composition, Treatise on Geochemistry. Elsevier Ltd., pp. 1-38.