Cannabinoids dansylation

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. 

Dansyl cannabinoids Hexane/dichloro- methane/methanol 360 490... 

The separation between the different dansyl-can-nabinoids can be obtained by the use of the one or two-dimensional TLC. Autoradiographies showed that the major difficulty is to have a good separation between dansyl-cannabinoids and 14C dansyl breakdown products which show several spots which are formed under the experimental conditions. All cannabinoids tested show one spot except CBD which give two spots. 14C DANS-neutral cannabinoids give a satisfactory separation in a one-dimensional TLC using the cyclo-hexane/ethyl acetate (95 5) (Fig. 9) and also in a two-dimensional TLC with cyclohexane/ethyl acetate (95 5) for the first migration followed by hexane/ benzene (60 40) for the second (Fig. 10). The best separation for the 14C DANS-ll-OH-A8 and A9-THC was obtained using the cyclohexane/acetone triethylamine (70 25 5) system (Fig. 11). 

Figure 6. Separation of neutral dansyl cannabinoids by one-dimensional TLC. Developing solvent cyclohexane/ethyl acetate (95 5). The striped spots indicate breakdown products of DANS-Cl. The left side of the plate shows the products of derivatization of standards. The right side shows a blank reaction mixture.

Alemany et al. (1993) resolved a mixture of cannabinoids in human plasma by extraction with a C-18 Sep Pak cartridge, derivatization with dansyl chloride and scanning at 340 nm. Jain (1993) studied interferences of adulterants on TLC... 

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See also in sourсe #XX -- [ ]

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