Determination of Harmful and Potentially Harmful Constituents in E-cigarettes, E-liquids, and Generated Aerosols

Abstract

Electronic nicotine delivery systems (ENDS), including e-cigarettes, are battery-operated devices which are vaped with the intent of delivering nicotine to the user. As these devices have become more prevalent on the market, so has the need to quantify different harmful and potentially harmful constituents (HPHCs) from those e-cigarettes. The FDA CTP has an established list of HPHCs, but my focus in collaboration with other labs was metals and volatile organic compounds (VOCs).

Throughout this work, both the unaerosolized e-liquids and generated aerosols were characterized for metals and VOCs. Commercial disposable e-cigarettes were purchased, their e-liquids were extracted, and those e-liquids were analyzed for metal content. Across different batches and lots of the same products, metal levels varied greatly. An early focus of the work was determining where the metals in the e-liquid come from, which necessitated x-raying and deconstructing products to determine where e-liquid contacts materials of construction. To further inform on the metals that may be present in e-cigarette aerosols, we developed and constructed an ENDS aerosolization machine to vape e-cigarette products. The ENDS aerosolization machine is sufficiently adaptable for use in aerosolizing commercially available ENDS products, as well as refillable products, with the aerosol collectable in a variety of manners to permit analysis of metal content, VOCs, and cellular effects. Using this machine, we have determined that metals, such as copper, chromium, nickel, and lead, are transferred from e-liquids into aerosols at different efficiencies depending on the e-liquid carrier vehicle and the type of metal in the starting e-liquid. Similarly, we have developed an effective approach for the characterization of VOCs produced by aerosolization. This necessitated capturing volatile and non-volatile components of the aerosol. Our methodology uses real-time derivatization of the VOCs, namely formaldehyde, acetaldehyde, acrolein, acetone, propionaldehyde, crotonaldehyde and 2-butanone, followed by extraction, and analysis via mass spectrometry. From this body of research, we have developed validated methods to analyze unaerosolized e-liquids and generated aerosols from e-cigarettes in order to better understand the harmful and potentially harmful constituents within.