Non-destructive sampling method for environmental and Geochemical exploration studies and XRF determination of Cl, F, and Br

Abstract

In this study, halogens are determined in rocks, soils, and sediments using sequential wavelength dispersive X-ray fluorescence spectrometry (WDXRF) by means of a non-destructive sampling method from powder to pellet form. A calibration procedure is introduced which provides accurate data, and the detection limits of halogens which were verified with different geological reference materials. The sample powders with a 74 μm particle size were used to prepare pressed pellets. A set of 25 reference materials was scanned for calibration of the spectrometer, and another set of 11 reference materials was analyzed for evaluation of the accuracy. The analytical data obtained for the standard samples ranged from 26 mg/kg - 1200 mg/kg for Cl, 44 mg/kg - 6960 mg/kg for F, and 0.71 mg/kg-252 mg/kg for Br. These studies have also shown that standard pellets made from 2 g of powder are critically thick enough in measuring the final detection limits for Cl, F, and Br. Further, the analytical results obtained for halogens show mean RSD values ranging from 0.78% to 6.7% for Cl, 0.86% to 5.23% for F, and 0.01% to 0.59% for Br. The order of suitability of reference materials for halogen determination in this study is Basaltic rocks (BEN, BHVO-1, BIR-1) > Syenites (STM-1, SY-2) > Rhyolites (JR-1, JR-2, RGM-1). The fitness for purpose of the results was also evaluated using the quality test proposed by the International Global Geochemical Mapping Program (IGCP), from which it can be deduced that the method is adequate for geochemical mapping applications.