Cannabinoids and terpenes qualitative analysis by GC-MS

The gas chromatography mass spectrometry (GC-MS) screen method uses a full scan mode in MS to tentatively identify known and unknown/non-targeted chemical substances in a sample based on a match to an established mass spectral library. This method was used to qualitatively determine cannabinoids and terpenes profile changes before and after X-ray irradiation. One mL 200-fold diluted samples were spiked with an internal standard mix [Triphenylphosphate and Phenanthrene-d₁₀, (Sigma-Aldrich, Saint Louis, MO)], before being injected on Agilent GC7890B coupled with MS5977B (Agilent, Santa Clara, CA). Quality control samples were included in the sample batch.

The injection volume was 1 μL and the splitless mode was used at the GC injection port. Chromatographic separation was achieved in a 30 min run time using a DB-5MS column (30 m x 0.25 mm x 0.25 μm, Agilent) with 1 mL/min helium flow. The oven temperature program was set at 60°C at 1 min, followed by a 12°C/min ramp to 320°C and hold for 7.3 min. The transfer line temperature was set at 280°C, the ion source temperature at 250°C, and EI ionization energy at 70eV. Mass spectral data was acquired in the scan mode from 25 to 550 m/z at a speed of 2.8 scan/s. Tentative compound identifications are based on a comparison of electron impact mass spectra with the Wiley11/NIST 2017 Mass Spectral libraries and Cayman Spectral library. The match criteria from the compound mass spectra to the database must have a fit of greater than 90% match ratio and visually verified by the analyst. Major cannabinoids and terpenes detected in samples were confirmed with the standards purchased from Sigma-Aldrich, Cerilliant, and Emerald Scientific (San Luis Obispo, CA).