A Colorimetric Method for the Determination of Cannabinoids with Fast Blue BB Salt

Abstract

A simple colorimetric method for the determination of cannabinoids was developed, using Fast Blue BB salt. Fast Blue BB salt produced stable diazo compounds with cannabinoids in alkaline media. The absorption maxima of Δ8-tetrahydrocannabinol, Δ9-tetrahydrocannabinol, cannabidiol and cannabinol were at 488, 489, 470 and 490 nm, respectively. The molar extinction coefficients of the above cannabinoids were estimated to be 3.3, 2.9, 5.2 and 2.5×104, respectively, and the coefficients of variation (10 analyses) were 0.7, 0.4, 0.4 and 2.7 (%), respectively. The contents of these cannabinoids in extracts from six kinds of cannabis leaves were determined by the colorimetric method in combination with thin-layer chromatography. The results obtained were in good agreement with those obtained by the gas chromatographic method. © 1979, The Pharmaceutical Society of Japan. All rights reserved.