Application to rapid quantitative analysis using loose powder X-ray fluorescence analysis for sediment cores from geological CO₂ sequestration site

We investigated the rapid determination of 18 components (Na₂O, MgO, Al₂O₃, SiO₂, P₂O₅, K₂O, CaO, TiO₂, MnO, Fe₂O₃, S, Cr, Ni, Rb, Sr, Zr, Pb and Th) in sediment cores from geological CO₂ sequestration site by a loose powder XRF analysis. The rapid preparation to the loose powder specimen is to simply add 8.0 g of powdered rock sample into a sample cup and tapping the cup in order to pack it to a more consistent density. The XRF measurement was performed by the benchtop-type wavelength dispersive XRF spectrometer. Fundamental parameter (FP) quantitative method using geochemical standard materials for quantification of the loose powder specimen were investigated. The sediment core powders ground to less than 50 µm of mean particle size showed excellent reproducibility less than 5% in the relative standard deviation for the XRF intensities of analyte. The quantitative results of two geochemical standard materials (JSd-2 and JSl-2) by the loose powder XRF analysis showed adequate accuracies for the rapid analysis. In particular, the results of trace elements calculated by FP method were more accurate in comparison with them calculated by Scan Quant X (SQX) method. The lower limits of detection of the 8 trace elements estimated by the theoretical equation were 7.8 ppm for S, 3.2 ppm for Cr, 2.4 ppm for Ni, 4.2 ppm for Rb, 2.9 ppm for Sr, 2.7 ppm for Zr, 4.9 ppm for Pb, and 7.8 ppm for Th. (author)