Why is Sodium Thiosulfate used in water samples during testing?

Sodium thiosulfate is used in water sample testing specifically to neutralize halogen biocides, such as chlorine or chloramines, that may be present in the water. These biocides are often used for disinfection purposes but can interfere with the accurate testing of Legionella and other microorganisms. By adding sodium thiosulfate to the water sample, it reacts with and neutralizes these halogens, ensuring that they do not kill or inhibit the growth of microorganisms present in the sample. This neutralization allows for a more accurate measurement of viable bacteria in the sample, which is critical in assessing the risk of Legionella and ensuring proper management of water systems.

In contrast, while enhancing sample quality, speeding up testing, and preserving sample temperature are all important aspects of water testing, they are not the specific functions of sodium thiosulfate in this context. Sodium thiosulfate's primary role is focused on neutralizing halogen biocides to ensure test results accurately reflect the presence of Legionella in the sampled water.