What is the purpose of using sodium thiosulfate in chlorinated samples?

Using sodium thiosulfate in chlorinated samples serves the crucial function of dechlorination. When chlorine is present in a water sample, it can interfere with various analyses, especially when determining other chemical parameters or microorganisms in the sample. Sodium thiosulfate reacts with chlorine to neutralize it, effectively eliminating its effects and allowing for accurate measurements of other analytes.

This dechlorination is particularly important in microbiological tests, where residual chlorine can kill or inhibit the growth of bacteria, leading to misleading results. By using sodium thiosulfate, analysts can ensure that the sample's composition is accurately represented for subsequent testing, thereby maintaining the integrity of their analytical results.