Detection limits of selected rare-earth elements in electron-probe microanalysis

Based on statistical analysis of repetitive measurements, definitions of concentration at the detection limit from the literature were specified as four types: 1) peak separation, 2) qualitative detection limit, 3) quantitative detection limit and 4) the minimum amount of an element guaranteed detectable. As a new approach for a given mean value of accumulated counts on the background, a reverse calculation yields the mean value of the accumulated count on the peak fulfilling criteria (1) to (4). Based on the reverse calculation, a diagram is constructed that allows the use of averages of accumulated raw counts of peak and background to decide whether the analysed concentration can be used as a quantitative result. The method is valid for any analytical condition and does not need a matrix correction. Results are given for La, Nd, Sm, Gd, Ho and Yb in olivine, orthopyroxene, clinopyroxene and garnet.