In prepared water sample bottles used for bacteriological examination, what effect does sodium thiosulfate have on the sample?

In prepared water sample bottles used for bacteriological examination, what effect does sodium thiosulfate have on the sample?

• A. It eliminates the need for refrigeration of the sample
• B. It neutralizes any chlorine present in the sample
• C. The test for it is relatively inexpensive and easy to perform
• D. None of the above

Answer: (B)

The test focuses on dechlorination. In water samples collected for bacteriological testing, any remaining chlorine can continue to disinfect the sample after collection, reducing or eliminating the bacteria present. Sodium thiosulfate acts as a dechlorinating agent, reacting with chlorine species (free chlorine and chloramines) to form innocuous products like chloride and sulfate. This stops further disinfection, preserving the actual bacterial content for accurate analysis. That’s why the correct description is that it neutralizes any chlorine present in the sample. It doesn’t replace refrigeration or relate to the ease of testing.

The test focuses on dechlorination. In water samples collected for bacteriological testing, any remaining chlorine can continue to disinfect the sample after collection, reducing or eliminating the bacteria present. Sodium thiosulfate acts as a dechlorinating agent, reacting with chlorine species (free chlorine and chloramines) to form innocuous products like chloride and sulfate. This stops further disinfection, preserving the actual bacterial content for accurate analysis. That’s why the correct description is that it neutralizes any chlorine present in the sample. It doesn’t replace refrigeration or relate to the ease of testing.