Speciation of bulk materials

Due to bonding of oxygen atoms to the p-orbitals, S Kα fluorescence energy increases with the change of sulphur oxidation state from S^2- to S⁶⁺. The energy shift can be observed with a change to the 2Θ angle of the S Kα fluorescence peak on laboratory based XRF. If the S Kα fluorescence is measured for a mixture of a sulphide and sulphate compounds, the 2Θ angle is shifted proportionally to the amount of each component. This relationship allows an empirical calibration to be established linking the ratios of S^2- and S⁶⁺ sulphur species. If the ratio is applied to the total sulphur concentration the amounts of sulphide and sulphate can be deduced.