Studies on identification of cannabis seeds. I: Qualitative and quantitative analysis of cannabinoids in cannabis seeds

In order to develop a chemical method for discrimination between seeds of Cannabis sativa L. and those of other plants, cannabinoids in the cannabis seeds were determined. Both Δ⁹-tetrahydrocannabinol (THC) and cannabinol (CBN) were detected in cannabis seeds by thin-layer chromatography (TLC), gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). As a matter of course, any sports or peaks on the chromatogram of TLC or of GC corresponding to the authentic cannabinoids were not detected in benzene extracts of seeds of other plants, such as Japanese radish (Raphanus sativus L. var. longipinnatus), radish (Raphanus sativus L.), spinach (Spinacia oleracea L.), komatsuna (Brassica rapa, var. pervidis Bailey), cabbage (Brassica oleracea L.) and Chinese cabbage (Brasica napus). Most of cannabinoids in cannabis seeds could be extracted with benzene without mashing the seeds, suggesting that the cannabinoids are localized on or near the skin. The contents of THC and CBN in cannabis seeds were determined by GC using 5α-cholestane as an internal standard. In the seeds harvested in 1986 and 1988, THC levels were 1.7 and 6.6 mg/100 g, and CBN levels were 0.6 and 0.8 mg/100 g, respectively. Those of THC and CBN in the commercially available cannabis seeds as feed for birds were 1.8 and 1.4 mg/100 g, respectively. These results indicate that analysis of THC and CBN by TLC or GC is useful for identification of cannabis seeds.