- Samples are precisely weighed precisely into tin capsules and dropped at pre-set times into combustion tube (at 1000°C). A constant stream of helium is maintained through tube.
- Helium stream replaced by pure oxygen for brief period prior to sample introduction.
- Sample instantaneously burned (flash combustion) followed by intense oxidation of tin capsule at 1800°C.
- Resulting combustion gases passed over catalysts to ensure complete oxidation.
- Gas stream dried by means of a water scrubber.
- Finally sulfur dioxide is separated from other interfering gases on chromatographic column and quantitatively measured by thermal conductivity detector.
The technique is generally free of interferences.
- Some inorganic materials may not liberate sulfur immediately, this can be remedied with the addition of additives to sample.
- A few compounds that contain phosphorus may form thermally stable compounds that may bind some sulfur.