Why are samples preserved at or below 6 degrees Celsius?

Samples are preserved at or below 6 degrees Celsius primarily to minimize bacterial activity. When environmental temperatures are decreased, the metabolic rates of microorganisms, including bacteria, are significantly reduced. This slowed metabolism helps to limit the growth and reproduction of bacteria that could otherwise alter the composition of the sample before analysis.

Keeping samples at low temperatures helps to maintain the integrity of the sample by preventing biological processes that could lead to changes in the sample's chemical and biological characteristics. This is especially important in wastewater analysis, where the presence of bacteria can indicate the level of contamination or organic material present in the sample. By minimizing bacterial activity, the results of the analysis remain accurate and representative of the actual conditions of the wastewater at the time of collection.

Preserving samples in this manner ensures that the data collected during testing are valid and that the sample reflects the true state of the wastewater at the time of sampling. Other options, while they may relate to sample handling, do not accurately describe the primary purpose of cooling samples.