At what temperature should samples be refrigerated for BOD analysis?

The correct temperature for refrigerating samples for Biological Oxygen Demand (BOD) analysis is 4 degrees Celsius. This temperature is critical for preserving the integrity of the samples before testing. Cooling samples helps minimize microbial activity that could alter the BOD results by either increasing or decreasing the oxygen demand in the sample due to additional bacterial respiration or die-off.

While the option listed as 6 degrees Celsius may seem close to the standard, it does not provide the same level of preservation as 4 degrees Celsius, which is the widely accepted recommendation. Maintaining samples at 4 degrees Celsius limits biological activity effectively, ensuring that the BOD readings reflect the original conditions of the sample rather than changes that might occur due to temperature fluctuations or microbial growth before analysis.

Choosing a temperature higher than 4 degrees Celsius can result in an inaccurate representation of the sample's true BOD because the increased warmth can accelerate microbial metabolism. Therefore, 4 degrees Celsius is the optimal temperature for refrigerating samples prior to BOD analysis, ensuring reliability in the results.