Thin layer chromatography cannabinoids

The abuse of cannabis cannot be detected by thin-layer Chromatography or by conventional gas Chromatography because the concentrations of cannabinoids in urine are too low. Immunoassay, applied to either blood or urine, is the best method (see B. Law et ah, J. analyt. Toxicol., 1984, <5, 14-... 

Cannabis and cannabis resin can be presumptively identified using the Duquenois Reagent (p. 133). Individual cannabinoids can be separated by thin-layer Chromatography (p. 172), gas Chromatography (p. 197), or high pressure liquid Chromatography (p. 217). 

Thin layer chromatography provides a rapid, easy and cost-effective means for screening for cannabis materials and making comparisons between seizures. The cannabinoids are readily oxidized and so should be prepared for TLC in a solvent in which they are stable. As with the swabs for trace samples, ethanol satisfies this criterion at this stage. 

A recent study of Mexican and Japanese strains grown in Japan showed no difference between the cannabinoid contents of the sexes. The following data on the appearance and thin layer chromatography of marijuana smuggled into Britain show that it is possible to get a fairly good idea of its origin if all facts are considered. 

Chromatography on thin layers of silica gel or alumina is a standard technique for identifying and separating marijuana constituents. Marijuana is extracted with solvent as described above, and a small amount is spotted with a capillary tube or micropipette on one end of the plate. The plate is then placed vertically in a small amount of solvent. The solvent is drawn to the other end by capillary action, which carries the cannabinoids present in the... 

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