Abstract
A sensitive and quantitative analytical method for determining elemental sulfur in a biological system was developed. Elemental sulfur was determined after extraction with petroleum ether by cyanolysis and ferric thiocyanate color formation in acetone. The method was successfully applied to show that sulfide was oxidized by Thiobacillus thiooxidans to elemental sulfur nearly stoichiometrically when further oxidation of elemental sulfur was inhibited by N-ethylmaleimide.Key words: elemental sulfur, quantitative analysis, sulfide oxidation, Thiobacillus thiooxidans.