The determination of sulphur and sulphur-35 in milk

Abstract

Sulphur compounds in milk are oxidised quantitatively to sulphate with Benedict's reagent. The sulphate is determined gravimetrically as barium sulphate, and the sulphur-35 content determined by radioassay of an aliquot of the barium sulphate as a gel in a scintillation medium. The presence of sodium hydroxide during the oxidation is essential for good recoveries. The validity of the method was confirmed by use of spikes of sulphur-35 labelled amino-acids. The limit of detection of the method is 50 pCi litre^–1.