MERITS OF USING BARIUM AS A HEAVY ABSORBER IN MAJOR ELEMENT ANALYSIS OF ROCK SAMPLES BY X-RAY FLUORESCENCE - NEW DATA ON ASK-1 AND ASK-2 REFERENCE SAMPLES

摘要

It has been demonstrated that XRF analysis of fused discs doped with Ba instead of La can give acceptable results for major element analysis of silicate rock samples, which are comparable to those obtained from La-doped fused discs. Replicate analysis of reference samples using Ba-doped fused discs indicated an analytical precision of approximately 1% and an accuracy of better than 3% for most of the elements, Another advantage of using Ba as a heavy absorber was that it allows simultaneous determination of Na along with other major elements on the same disc. Sodium levels determined by this method are in good agreement with the results of XRF analysis using pressed powder pellets, However, with Ba-doped discs there could be some difficulty in the determination of Ti and Mn as Ba L alpha 1 and L tau 2 lines are in close proximity to Ti and Mn K alpha lines, respectively, causing enhancement of the background signals of Ti and Mn. This can be avoided by carefully selecting suitable background angles, New major elemental analytical data are provided for the Norwegian reference samples ASK-1 (larvikite) and ASK-2 (schist) as the recommended values for these are not available in the literature. [References: 9]