Thirdhand smoke (THS) deposits to surfaces following smoking events and is a source of chemical exposure to humans. However, the evolution of THS in indoor environments is not well understood. Cannabis THS is a chemically distinct and prevalent form of THS, which has not been studied. The heterogeneous reaction of Δ9-tetrahydrocannabinol (THC), a major component of cannabis smoke, with ozone was examined as a pure compound and within cannabis smoke. Oxidative decay via ozonolysis and product formation were monitored by liquid chromatography–tandem mass spectrometry. Epoxide, dicarbonyl, and secondary ozonide THC reaction products were detected from both pure THC and cannabis experiments, with the product ratios dependent on relative humidity. The observed reaction kinetics for loss of THC on glass and cotton surfaces are consistent with a relatively short loss lifetime, which will be strongly dependent on the film thickness, ozone mixing ratio, and ozone reactivity of the surface substrate. The low volatility of THC and its oxidation products suggest that their contributions to thirdhand cannabis smoke will be less significant than the role that nicotine plays in thirdhand tobacco smoke.

Glycosidically bound, but not free, dietary sialic acids are used for the biosynthesis of new glycoconjugates in humans, making the quantitation of these two forms in infant food sources important, as in neonates the demand for sialic acid may exceed the de novo biosynthetic supply. Here, a rapid high-performance liquid chromatography-mass spectrometry method was developed to identify and quantitate glycosidically bound and free sialic acids in infant formulas. The sialic acid contents of eight commercially available infant formulas with varying protein source or manufacturer were investigated. The formula protein sources (whey vs casein) did not have a large impact on the ratios of free to bound sialic acids, nor did protein hydrolysis or sample form (solid vs liquid). Hydrolyzed bovine whey protein-based formulas were found to contain the highest amount of the most abundant human sialic acid, 5- N-acetylneuraminic acid (Neu5Ac). O-Acetylated Neu5Ac was quantified in all formulas tested and, for the first time, 2-keto-3-deoxy-d-glycero-d-galacto-nononic acid (Kdn) was detected in several infant formulas.