The Influence of Spectral Interferences on Critical Element Determination with Portable X-Ray Fluorescence (pXRF)

Abstract

Field portable X-ray fluorescence (pXRF) spectrometers are routinely used in mineral resources studies. To date, mineral resources studies have largely focussed on the application of pXRF to the exploration for deposits of base and precious metals. By contrast, studies using pXRF for the quantification of critical elements in geological materials are scarce since these elements are difficult to determine with energy-dispersive pXRF technology. This study explores the capability of pXRF spectrometers to detect and quantify critical elements (Ba, P, Nb, V, Co, REE, W, Bi, Hf, and Ta) in certified reference materials (CRMs). While precision of many critical elements is acceptable (<20% RSD), accuracy can be poor (>50% difference) when using pre-installed factory calibration software. Spectra collected during the pXRF measurements show that poor accuracy and false positives tend to be associated with spectral interferences. Distinct combinations of spectral interferences (line overlaps, Compton scattered peaks, and Si escape peaks) were observed in the different matrix types. Our results show that critical elements may be determined in common geological materials when pronounced peaks occur in the spectra and that matrix-match of standards and samples is essential. Hence, XRF spectra should be routinely reviewed to identify erroneous quantification due to spectral interferences.

Non-Destructive Characterization of Mechanically Processed Waste Printed Circuit Boards: X-ray Fluorescence Spectroscopy and Prompt Gamma Activation Analysis

“…The detection of the rare earth elements (REEs) is possible in some of the testing modes for portable XRF other than the mining Cu/Zn mode that was used. Although, some researchers investigated and identified that the accuracy of determining critical elements such as the REEs can be poor with the portable XRF [32].…”

pXRF method development for elemental analysis of archaeological soil

“…This was demonstrated clearly in the proportional comparisons in Figure 3. Furthermore, the closely spaced K‐ and L‐lines (transitional and heavier metals) of an atom can cause spectral interferences between elements, resulting in over‐ and underestimation with wider error ranges when one element is in particular abundance and overlapping elements are in trace amounts (Gallhofer and Lottermoser 2018; Lemière 2018; Ravansari and Lemke 2018). Removing moisture and amending the calibrations accounts for spectral interference in these situations (Goff et al .…”

Chemical analysis of Hg0-containing Hindu religious objects

“…At low-to-moderate concentrations of lead, fundamental parameters methodologies generally resolve this interference fairly successfully. But at higher concentrations accurate deconvolution become more challenging [63,64]. Interestingly, Pb levels, as determined by ICP-OES, were higher than reported by the XRF.…”