Determination of Niobium, Zirconium and Major Elements in Geological Samples by X-ray Fluorescence Spectrometry with High-Pressure Powder Pelletization

Powder pelletization is a green and pollution-free sample preparation technique; however, conventional pressing at 400kN suffers from pronounced particle-size and mineral effects that often lead to large errors, and some samples are difficult to compact. Increasing the pressing load reduces inter-particle voids and thus mitigates mineral effects. In this work, 800kN high-pressure pelletization was used to produce smooth, dense pellets from a wide range of silicate samples. Calibration curves were established with national certified reference materials of silicate rocks, sediments and soils. Matrix effects and spectral overlaps were corrected by empirical coefficients and internal standard methods. Comparison of surface morphology, calibration slopes and reproducibility showed that high-pressure pellets consistently outperformed those prepared at normal pressure: detection limits were lower and precisions for most analytes were below 1.0%. The relative standard deviations (RSDs, n = 4) of GBW07453 for Nb and Zr were 1.66% and 0.77%, respectively—substantially better than those obtained with conventional pressing (3.80% and 1.55%). The analysis of actual samples showed that the measured values of niobium and zirconium were consistent with the chemical values. High-pressure pelletization enables the simultaneous determination of Nb, Zr and major elements in geological samples by XRF, and the results meet the requirements of analysis.