A simple method for the parallel quantification of nicotine and major solvent components in electronic cigarette liquids and vaped aerosols

An analytical method was developed for the parallel quantitation of nicotine (Nic) and two key solvents (propylene glycol (PG) and vegetable glycerin (VG)) in e-cigarette (EC) liquids before vaping and from aerosols after vaping. For analysis of the EC refill solutions, the samples were diluted by a factor of about 100 in methanol. The aerosol samples generated by a modified international puffing protocol were initially collected on Cambridge filter pads and extracted with methanol. Both types of samples were analyzed by a gas chromatography-flame ionization detector (GC-FID) together with the mass change tracking (MCT) procedure introduced in our earlier study. The recovery of all three target components (Nic/PG/VG) in both EC liquid and aerosol samples was assessed after spiking Nic at four different concentrations (2, 5, 10, and 20 mg g− 1) in the e-solutions (prepared in the laboratory at three different PG:VG mass ratios of 10:0, 5:5, and 0:10). The method recoveries of Nic, PG, and VG in the e-liquid samples were 96.0 ± 1.0, 96.0 ± 1.2, and 101.4 ± 6.9%, respectively, while those in the aerosol samples were slightly lower at 94.7 ± 5.6, 85.5 ± 3.0, and 91.4 ± 15.7%, respectively. The amounts of VG and Nic in the e-liquid had a significant influence on the emission factors of PG, VG, and Nic. The detection limit values (ng) were 0.36 (Nic), 0.72 (PG), and 8.15 (VG) for the liquid samples and 0.51 (Nic), 0.96 (PG), and 3.99 (VG) for the aerosol samples. Overall, this method was reliable enough to determine each target in both liquid and aerosol samples.