The Duquenois test is employed throughout the world as part of the identification procedure for cannabis. A survey of results published for more than 400 herbally derived and botanical materials originating from some 270 different plant species is presented. A survey of results from some 200 organic compounds is also presented. The data show that the D-L modification is the most specific. There is no published report of an obviously botanical material, apart from cannabis, that gives a positive D-L test. Apart from cannabinoids, some resorcinol derivatives give a positive test. All of the materials are easily distinguished from cannabis by TLC.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&d...

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Note added at 6 mins (2004-12-31 16:49:58 GMT)
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Bill Warden, a registered sanitarian with the Sapulpa Health Department, testified that State\'s Exhibit No. 3 was tested and found to be cannabis sativa, commonly known as marihuana. He stated that he had performed the Duquenois reagent test on the substance and made a microscopic examination of it. On cross-examination Mr. Warden testified that he knew of no substance other than marihuana which [546 P.2d 1346] would produce a positive reaction to the Duquenois reagent test. He further testified that the substance had the odor of marihuana.
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