Figure 3: Percentages of direct determinations from the dilution factor with statistically significant differences (at 95% CL) with respect to the value found from the slope (see Table 4 and Figures 1(a) and 1(b)) in MT and TL matrices). Classes “a” and “b” refer to isotopes with an ordinate in origin statistically nondifferent and statistically different from zero at 99% CL, respectively (see text for explanation). The “figure of merit” (as defined in the text) pursuits the digested mass with the best compromise between precision and accuracy.