Valence-state speciation of sulfur by x-ray fluorescence spectometry and Kalman filtering

Abstract Dual-crystal, high-resolution x-ray fluorescence spectrometry produces overlapped peaks for the four valence states of sulfur [S(VI), S(IV), S(0) and S(−II)]. Spectra were recorded from 110.300° to 111.295°, and 200 data were collected but 131 points selected, and the Kalman filtering algorithm was applied to data processing for sulfur speciation. For 11 mixtures of sulfate, sulfite, sulfur and sulfide, the recoveries for each state were in the range 92–105%.