# UVA and UVB Photolysis of Natural and Synthetic Cannabinoids Studied by Online Mass Spectrometry

## TL;DR

This study uses mass spectrometry to investigate how UVA and UVB light affect the stability of various cannabinoids, finding that natural cannabinoids degrade significantly under UVB but not UVA.

## Contribution

The first directly comparable photolysis measurements for key phytocannabinoids using an online mass spectrometry approach.

## Key findings

- Natural cannabinoids like THC and CBD show significant photodegradation under UVB (280 nm) light.
- Synthetic cannabinoids (JWH-018, MDMB-FUBINACA) show negligible degradation under UVB.
- No significant degradation was observed for any cannabinoids under UVA (365 nm) light.

## Abstract

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.