How do I calculate the amount of sodium thiosulfate needed to remove the chlorine in the sample?

Document ID

Document ID TE213

Published Date

Published Date 27/05/2017
Question
How do I calculate the amount of sodium thiosulfate needed to remove the chlorine in the sample?
Summary
Dechlorinating samples using sodium thiosulfate
Answer
Using solid thiosulfate:
- Add 7.0 mg of catalog number 46001 (sodium thiosulfate, pentahydrate, ACS grade) for every milligram of chlorine. 

Using the Hach thiosulfate standard solution PN 2409353:
 - Use 1.13 mL of 0.0250 N thiosulfate standard solution for every milligram of chlorine

The amount in milligrams of Cl2 in a sample = (concentration result from a chlorine test) x (the number of liters of sample that is being treated).
Example: 500 mL sample of 2.0 mg/L = 1 mg Cl2.