In the first stage, the evolution of the instrumental limits of detection
calculated for each element (with respect to the dried sample volume
used for WDXRF analysis) was studied (see Fig. 4). As expected, the
higher the sample volume used, the lower the limit of detection was
until a constant valuewas reached. Fromthese results, a sample volume
of 4mLwas fixed for further analysis as a compromise between the limit
of detection and drying time. Moreover, by using this volume, the
condition of a “thin layer” sample was ensured, and absorption effect
corrections were not required. In Table 3, limits of detection obtained
using a sample volume of 4 mL are presented together with the legal
limits established by international legislation organisms. As shown, for
all studied elements, the calculated detection limits were in the μg L−1
range