Single particle analysis of polydisperse metal-bearing particles in cannabis vape liquids by organic mode ICP-MS

Abstract

The popularity of vaping cannabis-derived concentrates has grown rapidly since its legalization in several countries around the world. There is some limited evidence that metal-bearing nanoparticles (NPs) may be present in cannabis vape liquids. However, owing to the complexity of the cannabis vape liquids matrix, data on particle number concentration and particle size distribution are not available. Single particle inductively coupled plasma mass spectrometry (ICP-MS) is a technique widely used to obtain this information for samples in aqueous suspension; however, cannabis vape liquids are not water soluble. Additionally, this technique has not been well tested on naturally formed polydisperse nanoparticles, such as those found in cannabis vape liquids. An approach based on single particle analysis in organic mode ICP-MS is proposed for assessing particle number concentration and particle size distribution in cannabis vape liquids. Three approaches for determining transport efficiency were assessed, and particle sedimentation under various conditions was studied. Finally, cannabis vape liquids from nine cartridges were analyzed for several metal-bearing particles (Fe, Ni, Al, Co, Cu, Cr, V, Zn, Pb, and Sn). All samples contained a substantial number of NPs, with three samples having a number of particles one to two orders of magnitude higher than the rest of the studied samples, and the particle size distribution was, in most instances, below 150 nm for all metals.