Winkler Test For Dissolved Oxygen - BOD₅

BOD₅

To determine five-day biochemical oxygen demand (BOD₅), several dilutions of a sample are analyzed for dissolved oxygen before and after a five-day incubation period at 20 °C in the dark. In some cases, bacteria are used to provide a source of oxygen to the sample; these bacteria are known as "seed". The difference in DO and the dilution factor are used to calculated BOD₅. The resulting number (usually reported in parts per million or milligrams per liter) is useful in determining the relative organic strength of sewage or other polluted waters.

The BOD₅ test is an example of analysis that determines classes of materials in a sample.