Thiosulfate
 
 
Visual Kits
Range MDL Method Kit Catalog No. Refill Catalog No.
5-50 ppm 5.0 ppm Iodometric K-9705 N/A

Method

Reference: APHA Standard Methods, 21st ed., Method 4500-SO3 2- B (2005).

Thiosulfate is an excellent reducing agent. It is used primarily as an antichlor, or chlorine-removing agent, in various chemical processes, including the bleaching of pulp, paper, and textiles.

CHEMetrics' method employs the iodometric chemistry. Although sulfite usually titrates as thiosulfate, the reagent has been formulated to inhibit high-level sulfite interferences. Thiosulfate is titrated with iodide-iodate titrant in acid solution using a starch indicator. Results are expressed as ppm (mg/L) S203.