Hemp
(Cannabis sativa) has been used to treat
pain as far back as 2900 B.C. Its pharmacological effects originate
from a large variety of cannabinols. Although more than 100 different
cannabinoids have been isolated from Cannabis plants,
clear physiological effects of only a few of them have been determined,
including delta-9 tetrahydrocannabinol (THC), cannabidiol (CBD), and
cannabigerol (CBG). While THC is an illicit drug, CBD and CBG are
legal substances that have a variety of unique pharmacological properties
such as the reduction of chronic pain, inflammation, anxiety, and
depression. Over the past decade, substantial efforts have been made
to develop Cannabis varieties that would produce large amounts of
CBD and CBG. Ideally, such plant varieties should produce very little
(below 0.3%) if any THC to make their cultivation legal. The amount
of cannabinoids in the plant material can be determined using high
performance liquid chromatography (HPLC). This analysis, however,
is nonportable, destructive, and time and labor consuming. Our group
recently proposed to use Raman spectroscopy (RS) for confirmatory,
noninvasive, and nondestructive differentiation between hemp and cannabis.
The question to ask is whether RS can be used to detect CBD and CBG
in hemp, as well as enable confirmatory differentiation between hemp,
cannabis, and CBD-rich hemp. In this manuscript, we show that RS can
be used to differentiate between cannabis, CBD-rich plants, and regular
hemp. We also report spectroscopic signatures of CBG, cannabigerolic
acid (CBGA), THC, delta-9-tetrahydrocannabinolic acid (THCA), CBD,
and cannabidiolic acid (CBDA) that can be used for Raman-based quantitative
diagnostics of these cannabinoids in plant material.