This standard specifies a method by determination of carbon dioxide (CO2), for the evaluation in an aqueous medium of the ""ultimate"" biodegradability of organic compounds at a given concentration by aerobic microorganisms. The method applies to organic compounds which are: a) water-soluble under the conditions of the test, in which case removal of DOC may be determined as additional information (see annex D); b) Poorly water-soluble under the conditions of the test, in which case special measures may be necessary to achieve good dispersion of the compounds (see, for example, ISO 10634) c) non-volatile or which have a negligible vapour pressure under the c