What is the primary function of sodium thiosulfate in water sampling?

Sodium thiosulfate plays a crucial role in water sampling, particularly when testing for chemical contaminants. Its primary function is to neutralize chlorine present in the water sample. Chlorine is often used as a disinfectant in water treatment processes, and if chlorine is present in a sample when it is being analyzed, it can interfere with various chemical tests and measurements. By adding sodium thiosulfate to the sample, the chlorine reacts with it and is effectively neutralized, allowing for more accurate results during subsequent tests. This process ensures that any analysis conducted on the water sample reflects the true quality and composition of the water without the distorting effects of residual chlorine.