The alkaline Beam test was described in the early 20th century as a method to detect what substance?
The alkaline Beam test was used to identify cannabis plant material. A specimen of the suspected plant material was mixed with an organic solvent, the extract dried and then several drops of 5% KOH in ethanol (or methanol) added. A purple color indicates cannabis.
Roger Adams and his graduate students at the University of Illinois, in the late 1930s and early 1940s, utilized the Beam test during their innovative work attempting to elucidate the structure of the psychoactive component of cannabis. They reported that the Beam test did not react with the psychoactive component of cannabis but rather another cannabinoid they had isolated and named cannabidiol based on the presence of two phenolic groups in this non-psychoactive compound.
Further study revealed that in addition to CBD two other naturally occurring cannabinoids, cannabidiolic acid and cannabigerol also give a positive Beam test.
Adams R. Marihuana. Bull NY Acad Med November, 1942;
Mechoulam R., Ben-Zvi Z. Hashish-XIII, On the nature of the Beam Test. Tetrahedron 1968;24:5615-5624
Submitted by: Michael Hodgman, MD on behalf of Herbs and Dietary Supplements Section