• forensic science;
  • marijuana;
  • cannabinoids;
  • cannabinol;
  • cannabidiol;
  • isotope ratio mass spectrometry;
  • compound-specific isotope ratios;
  • bulk isotope ratios;
  • gas chromatography;
  • mass spectrometry;
  • carbon isotope ratio;
  • δ13C;
  • drugs of abuse

Abstract:  Five marijuana samples were compared using bulk isotope analysis compound-specific isotope ratio analysis of the extracted cannabinoids. Owing to the age of our cannabis samples, four of the five samples were compared using the isotope ratios of cannabinol (CBN), a stable degradation product of Δ9-tetrahydrocannabinol (THC). Bulk δ13C isotope analysis discriminated between all five samples at the 95% confidence level. Compound-specific δ13C isotope analysis could not distinguish between one pair of the five samples at the 95% confidence level. All the measured cannabinoids showed significant depletion in 13C relative to bulk isotope values; the isotope ratios for THC, CBN, and cannabidiol were on average 1.6‰, 1.7‰, and 2.2‰ more negative than the bulk values, respectively. A more detailed investigation needs to be conducted to assess the degree fractionation between the different cannabinoids, especially after aging.