This document specifies techniques for preparing poorly water soluble organic compounds (i.e. liquid and solid substances) with a solubility in water of less than approximately 100 mg.l-1 and introducing them into test vessels for a subsequent biodegradability test in an aqueous medium using standard methods. The subsequent tests on biodegradability are primarily methods using the analysis of the released carbon dioxide described in ISO 9439 and the determination of the oxygen described in ISO 9408 and following the usual precautions for ISO 10707. Thus, one can notice that the methods measuring the removal of DOC are not appropriate. This document does not specify the biodegradation test methods; it is restricted to describing the techniques for introducing the test compounds into the test medium and to keep them in a dispersed state (Reference[4]). These techniques are implemented while observing the experimental conditions described in the standardized methods for evaluating biodegradability. It should be noted that volatile compounds may not be tested by the carbon dioxide method specified in ISO 9439. Users should be aware that some of the preparation methods described in this document might not be accepted by regulators for concluding on the ready biodegradability of tested compounds.