G-Probe-1 - An International Proficiency Test for Microprobe Laboratories - Report on Round 1 : February 2002 (TB-1 Basaltic Glass) |
| |
| Authors: | Philip J Potts Michael Thompson Stephen Wilson |
| |
| Institution: | Department of Earth Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK;School of Biological and Chemical Sciences, Birkbeck College, Gordon House, London, WC1H 0PP, UK;United States Geological Survey, Box 25046 MS 973, Denver Federal Center, Denver, Colorado 80225, USA |
| |
| Abstract: | Results are presented for round one of a new international proficiency testing programme designed for microprobe laboratories involved in the routine analysis of silicate minerals. The sample used for this round was TB-1, a basaltic glass fused and prepared by the USGS. Thirty nine laboratories contributed data to this round, the majority of major element results being undertaken by EPMA and the majority of trace elements by LA-ICP-MS. Assigned values were derived from the median of results produced by nine selected laboratories that analysed powdered material by conventional ICP-MS, INAA and XRF techniques using bulk powders of the sample. Submitted microprobe results were evaluated using a target precision calculated using the Horwitz function, adopting the same criteria as those used for "applied" geochemistry laboratories in the companion GeoPT proficiency testing programme for laboratories involved in the routine bulk analysis of silicate rocks. An evaluation of results from participating microprobe laboratories indicated that overall, data were compatible with this precision function. A comparison between the performance of bulk and microprobe techniques used in the analysis of the basaltic glass showed remarkably good agreement, with significant bias only observed for the major oxide MgO. |
| |
| Keywords: | proficiency testing quality assurance G-Probe TB-1 basaltic glass microprobe laboratories |
|
|
