Oxygen in a BOD sample is supersaturated (or too high), which negatively affects consistency of samples. How can I improve this?

Document ID

Document ID TE918

Published Date

Published Date 27/05/2017
Question
Oxygen in a BOD sample is supersaturated (or too high), which negatively affects consistency of samples. How can I improve this?
Summary
Oxygen concentration of BOD sample is supersaturated or too high
Answer
The reason for dissolved oxygen supersaturation is that the sample is at a much colder temperature than what the BOD method requires. Warm the sample in another bottle with headspace to about 20 °C and shake it for 5-10 minutes after warming. Shaking speeds the transfer of dissolved oxygen from the sample into the headspace of the bottle. Transfer the sample into a BOD bottle with dilution (as necessary) after this and analyze the dissolved oxygen.