Challenges in measuring low concentration of overlapping elements with EDS and the need for verification with secondary standard composition

Quantitative analysis using energy-dispersive spectrometry (EDS) has been shown to achieve high accuracy equivalent to that of wavelength-dispersive x-ray spectrometry (WDS) even in the case of highly overlapped X-ray peaks of major elements and high precision in the case of trace elements with concentrations below 1 wt.%. With reliable pulse pile-up correction, accurate, unnormalized EDS quantification was also demonstrated at count rates above 200 kcps. This work studies the EDS quantification of samples exhibiting these three analytical challenges simultaneously: quantification of trace elements (< 1 wt%), overlapping X-ray peaks of major elements (small peak on large peak), and high-count rates (to improve productivity of these measurements). A secondary standard was used to optimise and validate the collection conditions for the measurement of an unknown slag sample exhibiting a heterogeneous microstructure containing trace level of Mn. Accurate quantification down to 0.1 wt% and mapping of segregation in the order of 0.2wt% were possible with modern EDS technology.