The coulometric determination of trace levels of sulphur in gallium phosphide

Abstract

Sulphur present in gallium phosphide has been determined. At 950 °C gallium phosphide reacts with platinum and hydrogen to from Ga_xPt_y and platinum phosphide (PtP₂), and sulphur is catalytically converted into hydrogen sulphide. The latter is absorbed in an alkaline medium and determined by controlled-potential coulometry at a silver-gauze electrode. The determination of 0·05 µg of sulphur is shown to be possible, the blank value by this method amounting to 0·01 µg of sulphur.