What is the role of Sodium thiosulfate (STS) for raw water analysis

·      Sodium thio sulphate is added to the bottle before it is sterilized.

·      It may be in the form of a clear liquid, a white powder, or a white tablet in the bottom of the bottle.

·      The purpose of the sodium thio sulphate is to neutralize any residual chlorine that is present in the sample.

·      That residul chlorine which can interface with the microbial analysis of water.

·     These ions highly active and penetrate through the cell wall via lipids and destroy the enzymes in the cell.

·      This ions may be change (inhibit ) the actual results.

·       Sodium thio sulfate (STS) or Sodium meta bi sulfate (SMBS) can be used to neutralize  or remove residual chlorine ions.

·         It simply reacts and forms sodium hydrogen sulfate or sodium bisulfate which is an inactive salt.

         Na₂S₂O₃  + 4Hocl  + H₂o       -----          2NaHSo₄ + 4 Hcl

·         Add validated ( 2 ml of 3% ) Sodium thio sulfate (STS) is added to the water sample before sterilization. ( if any contamination that also sterilize and can not affect on the sample analysis).

Sodium thio sulfate Preparation Storage and Usage:

·         3 g of sodium thiosulfate weighted and dissolved the 100 ml of purified water.

·         This solution can be store under refrigeration (2  to  8⁰C) condition for maximum three months (validate the hold time process).

·         This neutralization of  residual chlorine will help to determine the actual microbial load in water sample and will not affect the microbial recovery.