DETERMINATION OF EIGHTEEN COMPONENTS IN SILICATE ROCKS BY X-RAY FLUORESCENCE SPECTROMETRY WITH HIGH DILUTION RATIO FUSION SAMPLE PREPARATION

The paper introduces a rapid analysis method of X-ray fluorescence spectrometry (XRF) to determine 18 components (SiO₂, Al₂O₃, TFe₂O₃, MgO, CaO, K₂O, Na₂O, TiO₂, BaO, MnO, P₂O₅, Cr₂O₃, V₂O₅, Rb, Sr, Zr, Cu and Ni) in silicate samples. Selecting the reference materials such as soil, stream sediments, rocks of national first-class standard material, ultrabasic rocks and clay, the method applies high dilution ratio (14:1) of mixed solvent to sample mass for fusion sample preparation and fits the calibration curve. Through Eagon2 automatic high frequency inductance fusion machine, 7.0000 g of mixed solvent (45Li₂B₄O₇+10LiBO₂+5LiF) and 0.5000 g of sample are mixed uniformly, adding 2 drops of saturated ammonium nitrate solution as oxidant and then 4 drops of saturated lithium bromide solution as release agent, followed by preoxidation at 700℃ for 4 min and fusion at 1120℃ for 9 min, and finally cooling naturally to room temperature for sample preparation. The above fusion method can ensure that the components to be measured are completely melted and the sample surface is smooth and flat. Verified by national standard substances, the accuracy and precision of test results are in line with the requirements of Quality Management Code for Laboratory Testing of Geology and Mineral Resources (DZ/T 0130-2006).