For the conversion of sulfur into an analyzable form, we have various method approaches available. One option is the combustion of the sample in oxygen. Released sulfur oxides are absorbed in hydrogen peroxide solution and converted into sulfate ions. The combustion can be done as Schöniger, Wickbold or tube combustion. Alternatively, sulfur can be converted into an analyzable form after pressure digestion with oxidizing acids.
For the quantification of sulfur ICP-AES-, IR-spectroscopic as well as titrimetric and ion chromatographic methods can be applied. Within the ICP-AES, sulfur is detected spectroscopically after ionization in a plasma. The IR-spectroscopy is based on the detection of the resulting sulfur dioxide from a combustion.
For the titrimetric methods, we have two main approaches available. For sulfur as a major or minor component, the titration with barium ions and color indicator can be applied. For detections in the range of traces, the microcoulometric titration with electrolytically generated triiodine ions is used. Within the ion chromatography, sulfate is separated from other ions and subsequently quantified.
Also the XRF-spectrometry can be used to determine sulfur in some liquid matrices. After excitation of the sample by X-rays, the intensity of the resulting fluorescence radiation is analyzed.