In recent years, many analytical toxicologists have come to use the term ‘confirmation' of a first analytical ‘screening’ step as a substitute for ‘identification’. When this relates to cases in which the results from the detection or screening phase lead to the presumption that a certain substance is present, and in the confirmatory stage one or more signals from the unknown are matching those of the presumed candidate, the presumption is considered ‘confirmed'. However it should be realized, that such an approach does not necessarily provide unambiguous identification: it will always depend on the existence of similar analytical signal patterns of other compounds and on the actually provided information capacity, whether another substance cannot be distinguished from the presumed one. Thus, it has always carefully considered whether the exclusion criterion mentioned above is fulfilled.