The United States Food and Drug Administration (FDA) Family Smoking Prevention and Tobacco Control Act empowered the FDA to protect public health by regulating the manufacturing, distribution, and marketing of tobacco products. In its guidance for Premarket Tobacco Product Applications for electronic nicotine delivery systems (ENDS), FDA recommends that applicants evaluate chemical changes in their product over its shelf-life and provide complete product characterization. Compounds commonly used in the e-liquids of ENDS, such as propylene glycol (PG) and glycerin (VG) have the potential to degrade through oxidation, acidification, or radical processes during storage, resulting in new compounds. Because these new compounds may potentially transfer into the aerosol, resulting in consumer exposure, it is necessary to identify them as part of product characterization.

A semi-quantitative gas chromatography-mass spectrometry (GC-MS) based non-targeted analysis (NTA) screening method was utilized for chemical characterization. The aim of this work was to characterize degradants arising from PG and VG during storage and build a custom mass spectral database of known degradants, in addition to the NIST database, for an improved compound identification. A simplified e-liquid of PG/VG (60/40 w/w 1.6% nicotine 1.2% benzoic acid) without flavor ingredients was conditioned at high temperature (100° C) to accelerate the potential reaction processes.

This presentation will include examples of PG- and VG-related compounds in simplified e-liquid formulations, such as propylene glycol acetate, 2,4-dimethyl-1,3-dioxolane-2-methanol, or hydroxyacetone. Because PG and VG are used as e-liquid carriers across the ENDS industry, the results of these studies will expand foundational knowledge and improve the ease of NTA identification generally.