Modified Sturm Test (OECD 301B)

Freshwater Modified Sturm Test (OECD 301B / EC C.4.3)

This method is suitable for non-volatile substances that may be poorly soluble in water.

The amount of carbon dioxide (CO2) produced as a percentage of theoretical yield (based on total organic carbon analysis) is used as a basis for assessing whether the material biodegrades. CO2 is measured by way of a sodium hydroxide trap. The study is run for a minimum of 28 days and may be continued if the yield of CO2 is showing signs of increase towards the end of the 28 day period.

A positive control of sodium acetate is run alongside and a degradation of greater than 60% over 28 days should be seen. A blank control containing just the inoculum and nutrient mixture is used to check background levels of activity.


This method is suitable for assessing the biodegradability of poorly soluble, non-volatile substances in the freshwater environment.

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