Tracking metal presence in cannabis vaping products from source to inhalation

Vaping cannabis liquids is a convenient method of cannabis consumption, and is considered to be a less harmful alternative to smoking cannabis. However, vaping cannabis carries its own health risks, with many uncertainties, especially concerning the presence of metal particles in vape liquids. The heterogeneous distribution of these particles within the liquid matrix poses analytical challenges in measurement reproducibility. In this study, total metals analysis was performed on five samples from six different legal Canadian cannabis vape liquid products. The results indicated that metals from the vaping device components, cobalt (Co), nickel (Ni), and zinc (Zn) significantly contributed to within-batch variability. In contrast, all analyzed metals showed significant variability among tested products. Single-particle ICP-MS detected metal particles of aluminum (Al), Co, chromium (Cr), copper (Cu), Ni, tin (Sn), and Zn in the vape liquids. To assess potential consumer exposure, cannabis cartridges were vaped using a vaping machine and the resulting aerosol was analyzed. Although the number of detected emitted particles was below the limit of quantitation, all samples produced aerosols containing metal particles of Co, Cr, Ni, lead (Pb), Sn, and Zn. Further analysis using SEM-EDS on the emptied cartridges showed cracking on the connector pin of an unused device, suggesting a potential source of contamination during use and storage. The elemental composition of the metal components in the cartridges matched the detected particles, providing strong evidence that cannabis vape liquids are contaminated by the metal components of vaping devices.