Determination of 14 Major and Minor Elements in Ultrabasic Rocks and Chromite Samples by X-ray Fluorescence Spectrometry with Fusion Sampling

Ultrabasic rocks and chromite ores are closely associated in genesis, and actual samples are often intermingled within transitional zones, making accurate differentiation difficult during routine sampling. Traditional analytical methods mostly rely on conventional chemical analysis techniques such as volumetric analysis, colorimetry, and atomic absorption spectrometry (AAS), which involve cumbersome procedures, inability to perform simultaneous multi-element determination, and low analytical efficiency. Analytical methods such as inductively coupled plasma-optical emission spectrometry (ICP-OES) and X-ray fluorescence spectrometry (XRF) are also mostly designed for a single sample type, making it difficult to simultaneously accommodate both types. In practical testing, differences in sample type readily lead to biased results and reduced detection efficiency, which is unfavorable for batch sample analysis. This paper establishes an analytical method for the simultaneous determination of 14 major and minor elements (Cr, Si, Al, Fe, Ca, Mg, Ti, P, Mn, Na, K, V, Co, Ni) in ultrabasic rock and chromite ore samples by fusion sample preparation combined with wavelength-dispersive XRF. A mixed flux of lithium tetraborate, lithium metaborate, and lithium fluoride (mass ratio 65:25:10) was used, with ammonium bromide solution as the release agent, lithium nitrate as the oxidant, and a sample-to-flux dilution ratio of 1:35. The glass fusion beads were prepared at 1100℃. To address the wide concentration range of Cr, dual-channel segmented calibration curves (low-content and high-content) were constructed. The empirical coefficient method was used to correct inter-element absorption-enhancement effects, combined with the Compton scattering internal standard method and spectral line overlap interference correction, effectively overcoming the influence of the complex matrix. The method detection limits for each component ranged from 0.002% to 0.052%, the relative errors (RE) were −0.04% to 3.16%, and the relative standard deviations (RSD) were 0.23% to 4.61%, all meeting the requirements of DZ/T 0130—2006. The method was applied to the analysis of actual samples from the Sartuohai mining area in Xinjiang, and the results were in good agreement with those obtained by chemical methods. With a single preparation, this method enables the rapid and accurate simultaneous determination of major and minor elements in both ultrabasic rock and chromite ore samples, significantly improving analytical efficiency and making it suitable for the simultaneous batch analysis of large-scale geological exploration samples.