Determination of Nicotine in Electronic Tobacco Oil by Ultra-High Performance Convergent Chromatography

The sample of electronic tobacco oil (about 0.2 g) was dissolved with methanol, and the solution was diluted to 25.0 mL, filtered through 0.2 μm filter membrane and used for analysis by ultra-high performance convergent chromatography. The ACQULITY UPC² Trefoil CEL2 column (2.1 mm×50 mm, 2.5 μm) was used as the stationary phase, the column temperature was 50℃, and the system pressure was 13.3 MPa. The mobile phase was a mixture of supercritical CO₂ and methanol with a volume ratio of 94:6, with a flow rate of 2.0 mL·min^-1. A diode array detector was used with the detection wavelength of 259 nm. The results showed that linear relationship was found between peak area and mass concentration of nicotine in the range of 6.41-641 mg·L^-1, and the detection limit (3S/N) was 0.1 mg·kg^-1. The method was applied to the determination of nicotine in three different kinds of electronic cigarette oil, giving results consistent with those obtained by gas chromatography-mass spectrometry, and the relative standard deviations (n=6) of the measured values were between 0.10%-0.54%.