1.1 Subject contents
This Standard specifies the iodometric method for the determination of sulfides in water and waste water. The sulfides specified in this Standard refer to the deliquescent inorganic sulfides and acid soluble metal sulfides in water and waste water.
1.2 Application scope
1.2.1 This Standard is applicable to the determination of sulfides in water and waste water.
1.2.2 When conduct titration with 0.01 mol/L sodium thiosulfate solution for the specimen with 200mL in volume, this method is applicable to the determination of sulfides in water and waste water with the sulfide content more than 0.40 mg/L.
1.2.3 Interference and elimination of co-existing substances: Such reducing substances as thiosulfate and sulfite contained in the specimen produce positive interference. The suspended matter, chroma, turbidity and part of the heavy metal ion interfere the determination. When the sulfide content is 2.00 mg/L, the maximum permissible contents of interferent in the specimen are as follows: ; after the preprocessing of acidification - air blowing - absorption, the suspended matter, chroma and turbidity do not interfere the determination, but if the separation of is incomplete, the suspended matter, chroma and turbidity interfere the determination. The interference of 30 mg/L may be effectively eliminated by adopting zinc sulfide precipitation for filtering and separating the
