What chemical is used to dechlorinate bacteriological samples?

The correct choice is sodium thiosulfate, which is commonly used to dechlorinate bacteriological samples. This chemical works effectively by neutralizing chlorine in water, which is essential when conducting microbiological analyses. Chlorine can inhibit the growth of bacteria and other microorganisms, potentially skewing results when testing for their presence. By adding sodium thiosulfate to the sample, any residual chlorine is neutralized, allowing for accurate microbiological assessment.

Sodium thiosulfate achieves this by reacting with chlorine, converting it to a non-toxic compound that does not interfere with bacterial growth. This property is critical when sampling water for microbiological testing, ensuring that any bacteria detected in the samples are representative of the true microbial community present in the environment.

Other substances mentioned, like sodium sulfate, sodium bisulfate, and sodium bisulfite, do not serve the specific function of dechlorinating samples in the same way. Sodium bisulfite and sodium bisulfate can react with chlorine, but they are typically not preferred in microbiological protocols for this purpose. Therefore, sodium thiosulfate is the established and tested choice in laboratory practices for dechlorination of bacteriological samples.