Determination of sulfur in Soils and Stream Sediments by Wavelength Dispersive X-ray Fluorescence Spectrometry

Abstract

A simple, rapid and nondestructive wavelength dispersive X-ray fluorescence spectrometry (WD-XRF) was developed for the determination of sulfur in soils and stream sediments. WD-XRF was used to study the spectral line shifts and matrix effects of different inorganic species such as sulfide, elemental sulfur, thiosulfate, sulfite and sulfate. Analysis of the spectral lines in the S Kα wavelength range confirmed that Mo Lα (2θ = 111.799 °) lines interfered with S Kα (2θ=110.683°) lines. Twenty-seven soils and stream sediments reference samples were used to calibrate and evaluate the analytical method and the detection limit for sulfur was 5.43 mg/kg. The relative error (%RE) of the reference samples was −8.3–6.4%, showing good accuracy. However, the single form of sulfur (sulfide, sulfite and sulfate) had a significant matrix enhancement effect in the sodium carbonate matrix, especially for sulfides, and its relative error was 11.9 ~ 26.9%. The results of WD-XRF, inductively coupled plasma emission spectroscopy (ICP-OES) and elemental infrared analyzer were compared. The fitness for purpose of the results was also evaluated by the quality criteria test proposed by the International Geological Correlation Programme (IGCP), from which it can be deduced that the method was adequate considering geochemical mapping application.