DETECTION LIMITS AND ERROR ANALYSIS IN ENERGY-LOSS SPECTROMETRY.

The calculation of detection limits is fundamental to energy-loss spectrometry and a reliable estimate of error is important for quantitative analysis. To calculate both error and detection limit one needs a statistical analysis, and such an analysis can also be used to investigate the relative merits of various background-subtraction schemes for energy-loss imaging. Detection limits have been discussed before by Isaacson and Johnson. Their analysis shows that the minimum mass fraction decreases as the square root of the current density and collection time. However, it is not easy to apply their analysis to observed spectra. It is pointed out that it is often useful to be able to determine the proportion of an element that is detectable compared with a major constituent. This quantity can be easily related to the minimum mass fraction if the concentration of the major constituent in the sample is known.