Perspective. Impact of inductively coupled plasma mass spectrometry on certification programmes for geochemical reference materials

Abstract

The National Institute of Standards and Technology (NIST) began using inductively coupled plasma mass spectrometry (ICP-MS) for the certification of its Standard Reference Materials (SRMs) in 1986, only a few years after instruments first became commercially available. The United States, Canadian and Ontario Geological Surveys (USGS, CGS, and OGS, respectively) also made early use of the method to provide new data for existing certified reference materials (CRMs) and other non-certified geochemical reference materials (GRMs). The application of ICP-MS extends to most elements in the periodic table. NIST's efforts have focused largely on environmentally important trace elements. However, the impact of ICP-MS analysis in geochemistry is greatest in providing certified values for the platinum group elements (PGEs) and the rare earth elements (REEs). This paper will review the growing impact of ICP-MS analyses on the certification of CRMs/GRMs. Examples include NIST SRMs 1646a Estuarine Sediment, 2709-2711 Soils, 113b Zinc Concentrate; Centre de Recherches Petrographiques et Geochemiques (CRPG) CRMs CHR-Pt+ and CHR-Bkgr; Canadian Certified Reference Materials Program (CCRMP) WGB-1 gabbro rock, TDB-1 diabase rock and three other CCRMP CRMs recently certified for the PGEs. NIST has used ICP-MS almost exclusively in conjunction with isotope dilution. This has not been the situation among other users, but is to be recommended in certification analysis for several reasons, which will be outlined.