Table 1.
Characteristic time τ of the decrease (+sign) or increase (−sign) in the concentration of nicotine (nic), VG, PG, and water (H2O) in e-cigarette aerosol droplets generated from four different e-liquids. Reported are average values and standard deviations of τ retrieved from measurements of 5 or 6 single droplets generated from the same e-liquid.
| E-liquid properties | τnic (s) | τVG (s) | τPG (s) | τH2O (s) |
|---|---|---|---|---|
| 5% nicotine, pH 9.9 | +9.4 ± 3.7 | −7.4 ± 4.4 | +12.0 ± 5.9 | −7.0 ± 5.2 |
| 2% nicotine, pH 9.9 | +21.7 ± 8.1 | −9.74 ± 3.7 | +8.8 ± 3.6 | −12.7 ± 4.3 |
| 5% nicotine, pH 6.5 | −11.0 ± 5.5 | −18.8 ± 4.7 | +16.2 ± 7.0 | * |
| 5% nicotine, pH 3.4 | −31.2 ± 20.5 | −24.7 ± 17.4 | +28.2 ± 25.1 | * |
*These values could not be retrieved because the variation of the pH during droplet evaporation is unknown, and the retrieval of the H2O concentration in the droplet from the OH Raman band depends on the pH of the droplet.