Different Analytical Approaches to the Soil Analyses by <scp>TXRF</scp>

ABSTRACT Taking advantage of the proficiency test proposed by the IAEA PTNATIAEA21, a siliceous soil sample was analysed using four different analytical approaches using TXRF spectrometry. First, through acid digestion in a high‐pressure and high‐temperature microwave oven (MW); second, open vessel digestion (OV); and third and fourth, through suspension‐assisted direct solid analysis by using quartz (SA/DSA‐Q) and methacrylate (SA/DSA‐M) as sample reflectors. The analytical parameters obtained for each method have been compared, particularly the recovery, the detection limits and the expanded uncertainties at three levels, i.e., methodological reproducibility, instrumental repeatability, and roughness reproducibility for 22 analysed elements. In addition, a correlation study was carried out for each method versus the consensus values obtained in the proficiency test. The benefits and disadvantages of the fourth TXRF analytical approach are discussed and presented in this work.