Abstract
Portable X-ray fluorescence spectroscopy is now widely used in almost any field of geoscience. Handheld XRF analysers are easy to use, and results are available in almost real time anywhere. However, the results do not always match laboratory analyses, and this may deter users. Rather than analytical issues, the bias often results from sample preparation differences. Instrument setup and analysis conditions need to be fully understood to avoid reporting erroneous results. The technique’s limitations must be kept in mind. We describe a number of issues and potential pitfalls observed from our experience and described in the literature. This includes the analytical mode and parameters; protective films; sample geometry and density, especially for light elements; analytical interferences between elements; physical effects of the matrix and sample condition, and more. Nevertheless, portable X-ray fluorescence spectroscopy (pXRF) results gathered with sufficient care by experienced users are both precise and reliable, if not fully accurate, and they can constitute robust data sets. Rather than being a substitute for laboratory analyses, pXRF measurements are a valuable complement to those. pXRF improves the quality and relevance of laboratory data sets.
Highlights
Portable or handheld X-ray fluorescence spectroscopy has been a widely used on-site analytical tool since 1995 in many geoscientific fields—i.e., [1,2,3,4,5,6,7]
Portable X-ray fluorescence spectroscopy results gathered with sufficient care by experienced users are both precise and reliable, if not fully accurate, and they can constitute robust data sets
Most X-ray fluorescence analysers have one or more analytical modes (Table 1). Their name varies from one manufacturer to another depending on the material to be analysed or the calibration method (fundamental parameters (FP)), Compton normalisation, empirical method, and PMI
Summary
Portable or handheld X-ray fluorescence spectroscopy (pXRF) has been a widely used on-site analytical tool since 1995 in many geoscientific fields—i.e., [1,2,3,4,5,6,7]. The reliability and accuracy of this technique has been extensively discussed and compared with laboratory analyses on the same samples [8,9,10,11,12,13]. In many cases, this discussion suffered major flaws, which led to misinterpretations of discrepancies between pXRF and laboratory results. Let us mention the comparison with ICP analyses on digested samples; the comparison of field measurements on roughly prepared samples with lab quality pulps, not taking into account grain size or moisture effects; and the comparison of repeated field measurements with one laboratory sample with undocumented representativity.
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