ISO 3423:1975

Sulphuric acid and oleums for industrial use — Determination of sulphur dioxide content — Iodometric method

Applicable of products the SO2 content of which is equal to or more than 2 mg/kg. Based on the displacement of the sulphur dioxide present in the test portion by a current of pure nitrogen and absorption in a known volume of iodine solution. Titration of the excess of iodine with standard volumetric sodium thiosulphate solution. The diagram of the glass apparatus for absorption is shown in a figure.