This International Standard specifies a hydrogen peroxide/ barium perchlorate/Thorin 1) method for the determination of the mass concentration of Sulfur dioxide emitted from combustion facilities and technical processes with negligible amounts of Sulfur trioxide and sulfuric acid. lt is applicable from a minimum of 30 mg/m3 Sulfur dioxide by reference to sampling periods of normally 30 min. At mass concentrations of Sulfur dioxide greater than 2 000 mg/m3, the volume of the waste gas under investigation passed through the sampling train is 30 Iitres. Substances, which, if contained in the waste gas under investigation and thus in the waste gas Sample, are known to have an effect on the titration reading, are given in 7.4. Information on Performance characteristics is given in 8.2. At mass concentrations of Sulfur dioxide less than 30 mg/m3, a sampling period greater than that specified in this International Standard is used. All concentrations are based on dry gas at a temperature of 273,1 K and a pressure of 101,3 kPa.