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.
Excess oxygen removed as gases are swept through reduction tube containing copper at 650°C
Finally sulphur dioxide is separated from other interfering gases on chromatographic column and quantitatively measured by thermal conductivity detector.
Interferences
The technique is generally free of interferences.
Some inorganic materials may not liberate sulphur 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 sulphur.