Determination of Nicotine in E-Cigarette Liquid by Continuous Flowing Analysis

The e-cigarette liquid sample (0.100 0 g) was added into a 25 mL centrifuge tube with cover, and 10 mL of 15% (volume fraction) isopropanol solution was added to disolve the sample. After mixing well, the mixture was let stand to obtained the sample solution. If incomplete miscibility occured during standing, the centrifuge tube was oscillated at 5 000 r·min^-1 for 1 min in a vortex oscillator. After centrifugation, the clear liquid was taken as the sample solution. The absorbance of the sample solution at the wavelength of 460 nm was measured using a continuous flowing analyzer. Linear relationship was found between absorbance and mass concentration of nicotine in the range of 10.0-500 mg·L^-1, with lower limits of determination (10s) of 1.5 mg·L^-1. The proposed method was applied to determination of nicotine in liquid of commercially available e-cigarette, giving measured values basically consistent with the measured values. Values of recovery obtained by standard addition method were in the range of 99.5%-101%, and RSDs (n=6) was 0.66%.