Determination of nicotine in cartridge-based electronic cigarettes

Electronic cigarettes are a relatively new form of nicotine delivery and their popularity is increasing rapidly. One concern regarding the safety of electronic cigarette is quality control during their manufacture, including whether the nicotine concentration matches the labelling. An assay was developed to evaluate the concentration of nicotine in electronic cigarette cartridges. For nicotine extraction, the pad was removed from the cartridge. Deuterated nicotine solution (1 µg), used as the external standard, was added to the pad and allowed to penetrate into the matrix. The pad was treated with 50 mL of 50% (v/v) methanol/deionized water in an ultrasonic bath for fifteen minutes at ambient temperature. After sonication, the extract was further diluted with deionized water and then analyzed by ultra-high performance liquid chromatography–tandem mass spectrometry. The recovery of nicotine-d₄ was 81.5 ± 3.7%. Based on the recovery, the nicotine concentration in the electronic cigarette cartridges was 11.9 ± 1.3 mg, which was lower than the labelled concentration (16 mg). The nicotine concentration did not vary significantly between cartridges within one pack or between packs. The nicotine concentration in the electronic cigarette cartridges was determined by this assay. Differences between labelled and actual nicotine concentrations may affect clinical trials.