Cross-reacting cannabinoid

Teale and Marks have described a case in which a fatal traffic accident was due to the behaviour of a driver who, at post-mortem, proved to have plasma levels of 315 ng/ml THC-CRC (tetrahydrocannabinol cross-reacting cannabinoids) a volunteer experiment subsequently showed that, when using the same laboratory methods, a peak THC-CRC level of only 75 ng/ml was associated with euphoria (14 ). 

Although radio-immunoassays are rapid and convenient to analyze large numbers of samples, they lack absolute sensitivity and specificity, since cannabinoids cross-react within a given assay. Gas chromatography is no more satisfactory. However, when combined with mass spectrometry it is far more specific and sensitive, although extremely costly. Finally, fluorometric techniques have proved suitable for many applications such as the one based on gallium chelate formation which can only be used for urine (9), and more especially for applications based on cannabinoid dansylation (16-18). However, these last techniques only allow qualitative determination of A9-THC. 

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