Characterization of potential impurities and degradation products in electronic cigarette formulations and aerosols

Introduction:
This article reports a study that aimed to determine and quantify potential impurities and degradation products in the formulations and aerosols of four e-cigarettes manufactured by Nu Mark LLC, an altria company, and sold as MarkTen®. The study also conducted a risk assessment analysis of these e-liquid formulation impurities and aerosol chemicals.

Key Points:

* The study focused on measuring chemicals that are listed for cigarette tobacco and smoke on the abbreviated hPhC list published by FDa (2012b) as well as chemicals identified in publications focused on analytical characterization of e-cigarette liquid formulations and aerosols.
* Four commercial e-cigarette products were included in all analytical evaluations.
* all e-cigarette testing methodologies for formulation characterization were validated based on the 2005 International Conference on harmonisation (ICh) guideline “Validation of analytical Procedures: Text and Methodology q2(R1)”.
* aerosol collections were conducted under ISO smoking environmental conditions with temperature at 22.0/C14C±2.0/C14C and relative humidity at 60% ±5%.
* Carbonyls in e-cigarette aerosol were collected on a 5-port linear Borgwaldt, KC automation smoking machine using two impingers containing 30 mL of 2,4-dinitrophenylhydrazine (DNPh) and perchloric acid in acetonitrile.
* ammonia in e-cigarette aerosol was collected on a 20-port Cerulean smoking machine onto a CFP in series with two impinger traps containing dilute acidic solution (0.025 N sulfuric acid).
* The risk assessment calculations were performed for all listed potential impurities and degradation products for which there were published exposure limits as established by U.S. EPa, OEhha, aCGIh, OSha, or DFG.

Main Message:
The study found that most potential impurities investigated in this study were not detectable or were well below LOqs in the commercially available MarkTen®e-cigarettes analyzed. The levels of potential e-liquid formulation impurities and potentially harmful chemicals detected in the aerosol were determined to be below published occupational exposure limits using the aerosol collection regime discussed herein. The study suggests that the regulation of e-cigarettes should consider the specific chemicals and impurities present in e-cigarettes and their aerosols, and establish appropriate exposure limits to protect users.

Flora, Jason W., Naren Meruva, Chorng B. huang, Celeste T. Wilkinson, Regina Ballentine, Donna C. Smith, Michael S. Werley, and Willie J. McKinney. “Characterization of Potential Impurities and Degradation Products in Electronic Cigarette Formulations and aerosols.” Regulatory Toxicology and Pharmacology 74 (February 2016): 1–11. https://doi.org/10.1016/j.yrtph.2015.11.009.