Ambar S. A. Shaikh

Cannabinoids are of considerable current interest for use in pharmaceutical and non-medical consumer products. While there have been significant efforts to understand their chemical stability under ambient conditions, only sparse attention has been paid to characterising their photostability. Here, we present UVA (365 nm) and UVB (280 nm) photolysis measurements of eight representative cannabinoids, including natural compounds (THC, CBD, THCA, CBDA), metabolites (THC-COOH, THC-OH), and synthetic analogues (JWH-018, MDMB-FUBINACA). Measurements were performed using a novel online-electrospray mass spectrometry (MS) approach, where online photolysis of cannabinoid solutions was conducted with laser light-emitting diodes. MS detection was used to monitor precursor compound decay and photoproduct formation. Complementary results obtained via UV–Vis spectroscopy of photolysed cannabinoid solutions are also presented. For THC, CBD, THC-COOH, THC-OH, THCA and CBDA, significant photodegradation was observed with 280 nm photolysis, both through the appearance of photoproducts detected by MS and via time-dependent changes in the solution UV–Vis absorption profiles. In contrast, the synthetic cannabinoids (JWH-018 and MDMB-FUBINACA) showed negligible degradation with UVB photolysis, consistent with their relatively low absorbance propensity through the mid-UV region. No significant photodegradation was observed for UVA (365 nm) photolysis of any of the cannabinoids. The results presented here constitute the first directly comparable set of photolysis measurements for key phytocannabinoids.

Cannabinoids are of considerable current interest for use in pharmaceutical and non-medical consumer products. While there have been significant efforts to understand their chemical stability under ambient conditions, only sparse attention has been paid to characterizing their photostability. Here, we present UVA (365 nm) and UVB (280 nm) photolysis measurements of eight representative cannabinoids, including natural compounds (THC, CBD, THCA, CBDA), metabolites (THC-COOH, THC-OH), and synthetic analogues (JWH-018, MDMB-FUBINACA). Measurements were performed using a novel online-electrospray mass spectrometry (MS) approach, where online photolysis of cannabinoid solutions was conducted with laser light emit-ting diodes. MS detection was used to monitor precursor compound decay and photoproduct formation. Complementary results obtained via UV-Vis spectroscopy of photolysed cannabinoid solutions are also presented. For THC, CBD, THC-COOH, THC-OH, THCA and CBDA significant photodegradation was observed with 280 nm photolysis, both through the appearance of photoproducts detected by MS, and via time-dependent changes in the solution UV-Vis absorption profiles. In contrast, the synthetic cannabinoids (JWH-018 and MDMB-FUBINACA) showed negligible degradation with UVB photolysis, consistent with their relatively low absorbance propensity through the mid-UV region. No significant photodegradation was observed for UVA (365 nm) photolysis of any of the cannabinoids. The results presented here constitute the first directly comparable set of photolysis measurements for key phytocannabinoids.

Cannabinoid molecules are the family of molecules that bind to the cannabinoid receptors (CB1 and CB2) of the human body and cause changes in numerous biological functions including motor coordination, emotion, and pain reception. Cannabinoids occur either naturally in the Cannabis Sativa plant or can be produced synthetically in the laboratory. The need for accurate analytical methods for analyzing cannabinoid molecules is of considerable current importance due to demands for detecting illegal cannabinoids and for monitoring the manufacture of popular, non-illegal cannabinoid products. Mass spectrometry has been shown to be an optimum technique for identifying cannabinoids. In this work, we perform Higher Collisional Dissociation (HCD) mass spectrometric measurements on an Orbitrap Fusion Tribrid Mass Spectrometer to measure the collision-energy-dependent molecular fragmentation pathways of a group of key cannabinoids and their metabolites (cannabidiol, Δ9-Tetrahydrocannabinol, 11-Hydroxy-Δ9-tetrahydrocannabinol, 11-nor-9-Carboxy-Δ9-tetrahydrocannabinol, cannabidiolic acid, tetrahydrocannabinolic acid), along with two synthetic cannabinoids (JWH-018 and MDMB-FUBINACA). This is the first time that cannabinoid molecules have been studied using energy-resolved HCD methods. We identified a number of common, primary fragmentation pathways, including loss of water, loss of other small neutral molecule units (e.g., butene), and rupture of the central C-C bond that links the aromatic and alkyl ring groups. Quantum chemical calculations are presented to provide insights into preferred protonation sites and to characterize isomerization of protonated open-ring cannabinoids (e.g., [CBDA + H]⁺) into closed-ring analogues (e.g., [THCA + H]⁺). A key result to emerge from our study is that energy-resolved HCD measurements are particularly valuable in identifying isomerization, since the isobaric pairs of molecular ions studied here (e.g., [CBDA + H]⁺ and [THCA + H]⁺) are associated with identical HCD profiles indicating that isomerization of one structure into the other has occurred during the electrospray–mass spectrometry process. This is an important result as it will have general applicability to other tautomeric ions and thus demonstrates the application of energy-resolved HCD as a tool for identifying tautomerization proclivity.