Post-column derivatization procedure for the colorimetric analysis of tissue cannabinoids separated by high-performance liquid chromatography.

A new method for quantitating cannabidiol (CBD) and delta 9-tetrahydrocannabinol (THC) in mouse plasma and brain involves (1) the separation of CBD and THC from their major metabolites by the use of isocratic, reversed-phase high-performance liquid chromatography (HPLC), and (2) the on-line reaction of the cannabinoids with Fast Blue Salt B (FBB) as a the former elute from the column; the colored cannabinoid-FBB derivatives are then detected at 490 nm in a spectrophotometer with a sensitivity of less than 50 ng. In addition to this HPLC--FBB analytical procedure, a method for extracting CBD and THC from brain and plasma is described, and selected examples illustrate the procedure's application to the analysis of CBD and THC in mouse plasma and brain samples taken from animals injected with these two cannabinoids.