Cloud point extraction of Δ9-tetrahydrocannabinol from cannabis resin.
A cloud point extraction coupled with high performance liquid chromatography (HPLCUV) method was developed for the determination of Δ(9)-tetrahydrocannabinol (THC) in micellar phase. The nonionic surfactant Dowfax 20B102 was used to extract and pre-concentrate THC from cannabis resin, prior to its determination with a HPLC-UV system (diode array detector) with isocratic elution. The parameters and variables affecting the extraction were investigated. Under optimum conditions (1 wt.% Dowfax 20B102, 1 wt.% Na2SO4, T 318 K, t 30 min), this method yielded a quite satisfactory recovery rate (81 %). The limit of detection was 0.04 μg mL(-1), and the relative standard deviation was less than 2 %. Compared with conventional solid-liquid extraction, this new method avoids the use of volatile organic solvents, therefore is environmentally safer.