Determination of sulfur content in various oxidation states by WD – XRF

In natural and anthropogenic materials sulfur is mainly present in the form of sulfides (–2 oxidation state) and sulfates (+6 oxidation state). X–ray fluorescence spectrometry (XRF) can be used to quantify sulfide and sulfate phases in ores, concentrates, muds, oil and oil products with no sample destruction. This work concerns determination of sulfide and sulfate phases in mixtures synthesized from pyrite and sodium sulfate. Two sets of samples with different ratios of sulfides and sulfates were prepared and analyzed with wavelength–dispersive (WD) XRF spectrometer. Different methods were tried out to quantify sulfate and sulfide phases in a sample: determination of the sulfur Kα1,2 doublet line and Kβ line shifts in depending on phases content, determination of the absolute increase in the satellite Kβ′–line intensity, estimation of the ration between Kβ′ and Kβ lines intensities with sulfate content increase and sulfide content decrease. The influence of various cations and elemental sulfur presence on the analytical signal change were studied. The precision, accuracy, and reproducibility factors of the quantitative chemical analysis were computed.