Twenty-seven e-cigarette liquid formulations that contain nicotine between 6 and 22 mg/L were acquired within the United States and analyzed by various methods to determine their contents.
Personal battery-powered vaporizers or electronic cigarettes were developed to deliver a nicotine vapor such that smokers could simulate smoking tobacco without the inherent pathology of inhaled tobacco smoke. Electronic cigarettes and their e-cigarette liquid formulations are virtually unregulated. These formulations are typically composed of propylene glycol and/or glycerin, flavoring components and an active drug, such as nicotine. The samples in the current study were screened by Direct Analysis in Real Time Mass Spectrometry (DART-MS). Nicotine was confirmed and quantitated by high-performance liquid chromatography-tandem mass spectrometry, and the glycol composition was confirmed and quantitated by gas chromatography-mass spectrometry. The DART-MS screening method was able to consistently identify the exact mass peaks resulting from the protonated molecular ion of nicotine, glycol, and a number of flavor additives within 5 mmu. Nicotine concentrations were determined to range from 45 to 131 percent of the stated label concentration, with 18 of the 27 having >10 percent variance. Glycol composition was generally accurate to the product description, with only one exception where the propylene glycol to glycerin percentage ratio was stated as 50:50 and the determined concentration of propylene glycol to glycerin was 81:19 (percent v/v). No unlabeled glycols were detected in these formulations. (Publisher abstract modified)