Abstract
The paper describes determination of free sulfur and thiosulfate sulfur in substance containing sulfur of various state using two methods-the extraction-combustion method and vaporization-combustion method.
The outline of procedure is as follows:
(1) Determination of free sulfur
Sample is treated with 100 ml of carbon tetrachloride for 6 hours in Soxhlet's extractor. In this condition, free sulfur in sample is dissolved in solvent. Extracted liquid is evaporated by heating at under 100°C in alumina boat and free sulfur is educed. Free sulfur in material educed is analysed with conventional combustion method.
(2) Determination of the sum of free sulfur and thiosulfate sulfur
Sample is analysed by the apparatus of Fig. 1, and then free sulfur and the free sulfur produced from thiosulfate in sample is vaporized and oxidized by oxygen. Gas including sulfur oxides is absorbed with hydrogen peroxide solution. Sulfur in absorbent is determined by arsenazo III titration method.
(3) Determination of thiosulfate sulfur
Thiosulfate sulfur can be obtained as two times of the value of difference between the analytical values of the vaporization-combustion method and extraction-combustion method.
