What kind of samples is sodium thiosulfate typically used to preserve?

Sodium thiosulfate is commonly used to preserve water samples, particularly for the analysis of certain chemical parameters that can be affected by the presence of chlorine and other oxidizers. When added to a water sample, sodium thiosulfate effectively neutralizes chlorine, thereby preventing it from reacting with other constituents in the sample. This is crucial for accurate analysis, as chlorine can alter the concentrations of various analytes and lead to flawed results. In the context of wastewater analysis, maintaining the integrity of the water sample by using sodium thiosulfate helps ensure that subsequent tests reflect the true composition of the sample without interference from any chemical reactions that could otherwise occur.

Other types of samples like microbial, chemical, or soil samples may require different preservatives or handling techniques and are not typically preserved with sodium thiosulfate in the same manner.