Qualitative and quantitative analysis of synthetic cannabinoids in e-liquids by pyrolysis–gas chromatography/mass spectrometry

Synthetic cannabinoids (SCs) are a series of synthetic substances that mimic the effects of natural cannabis and cause more serious toxicity and public safety issues. SCs, with a wide variety and fast update rate have become the most abused family of new psychoactive substances. A pyrolysis–gas chromatography/mass spectrometry method has been developed to qualitatively and quantitatively analyze SCs in e-liquids using pyrolysis products as analytical targets, which can effectively expand the detection range of SCs. In qualitative analysis, diluted e-liquids were pyrolyzed in the microfurnace at 800, 600, and 300 ℃, respectively, followed by separation and analysis through gas chromatography/mass spectrometry. SCs in the e-liquids were determined by both shared and characteristic pyrolysis products combined with the EI mass spectrometry of their parent compounds. ADB-BUTINACA and 5F-MDMB-PICA were successfully identified in five e-liquid samples seized by local police. Furthermore, five popular SCs in the illegal market, ADB-BUTINACA, 4F-ABUTINACA, 4CN-CUMYL-BUTINACA, 4F-MDMB-BICA, and 5F-MDMB-PICA, were quantitatively analyzed based on their characteristic pyrolysis products as the analysis targets. The results indicated that the linear range of ADB-BUTINACA was 2–200 μg/mL, while those of 4F-ABUTINACA and 4CN-CUMYL-BUTINACA were 1–200 μg/mL. For 4F-MDMB-BICA and 5F-MDMB-PICA, the linear range was 5–500 μg/mL. The linear correlation coefficients of determination of five SCs were greater than 0.994. The limit of detection (S/N=3) for five SCs was 0.25–2.50 μg/mL, and the limit of quantification (S/N=10) was 0.50–5.00 μg/mL. This quantitative method was applied to five positive samples in real cases. The results showed that the concentrations of ADB-BUTIANCA and 5F-MDMB-PICA in the positive samples were 751.32–4810.10 μg/mL and 1109.41 μg/mL, respectively. The current research provides a validated pyrolysis–gas chromatography/mass spectrometry method, with simple pre-treatment, fast operation and wide screening range, to accurately identify and quantify SCs in e-liquid samples without reference materials.