The Specificity of the Duquenois Color Test for Marihuana and Hashish

The Duquenois color test [1,2], coupled when possible with botanical examination [3], is regarded as one of the most reliable indications of the trace presence of cannabinoids, the physiologically active constituents of marihuana and hashish [4]. Consequently, this color test is used widely in forensic laboratories in the United States. Analysis of extracts from a substantial number of plant families has failed as yet to discover any exception to the specificity of the test [3,5]. However, it is clear that an understanding of the chemical basis of the test would allow a better appreciation of the molecular features which are necessary for a positive color test, and an increased confidence in its specificity. With this end in mind, we have studied the minimum structural features of the cannabinoid skeleton which are necessary for a positive test.