Light Element Dilution Effects on Fused Borate Glass Bead Specimens for X‐Ray Fluorescence Analysis of Igneous Rock Samples

ABSTRACT Appropriate sample‐to‐flux ratios of fused borate glass bead specimens were investigated for igneous rock analyses. Severe interference of X‐ray absorption and enhancement engenders erroneous findings from X‐ray fluorescence spectrometric analyses, but light element dilution effects on glass bead specimens decrease this interference. The influences of several co‐existing constituents were examined to compare 1:10 and 1:100 dilution ratios for igneous rock using synthetic glass bead specimens consisting of a sample, an additional co‐existing element, and anhydrous lithium tetraborate. Effects of analytical lines on the X‐ray fluorescence intensity of Mg, Ca, and Fe, which have markedly different concentrations in igneous rocks, were investigated using synthetic samples. For sodium, which has a low‐energy (1.04 keV) analytical line, almost no effect occurred at a dilution ratio of 1:10 or 1:100. Because the energy of the analytical line (e.g., Al and Si) increases, the influence of co‐existing elements was significant at 1:10 dilution. By dilution to 1:10, titanium and strontium were confirmed as showing XRF intensity attenuation of about 10%, strongly affecting quantitative values. Dilution to 1:100 led to negligible influence on the analysis by titanium (4.51 keV), a major component of igneous rock. However, because of the high dilution of analyte (1:100) and the large peak‐to‐background ratio, obtaining reliable XRF intensity from the minor strontium content was difficult.