ISO 7099:1983

Phosphoric acid for industrial use (including foodstuffs) — Determination of hydrogen sulfide content — Titrimetric method

The hydrogen sulphide in a test portion is removed in a stream of nitrogen and absorbed in a solution of sodiumhydroxide in aqueous acetone. the sulphide ions are titrated with standard volumetric mercury(II) acetate solution, in the presence of 1,5-diphenylthiocarbazone (dithizone) as indicator. The method is applicable to products having hydrogen sulfide contents greater than or equal to 0.05 mg/kg.