Monitoring the nicotine delivery stability in electronic cigarettes based on in-situ AS/SRD/FOS technology.

Background: It is well known that e-cigarette regulations can be developed with the aid of focusing on nicotine flux (NF) and nicotine delivery stability (NDS), which are defined as the amount of nicotine released per puff under given conditions (vape + recipe). In this study, a convenient and fully automated puff-by-puff aerosol nicotine flux measurement method was developed by combining automatic smoking, spectroscopic rapid detection and fiber-optic sensing (AS/SRD/FOS) technology. Aerosol generated by an e-cigarette was introduced into an "impinger", at the meantime, nicotine was trapped in pure water. After the solution was stable, immediate spectral detection at full wavelength (200-600 nm) was accomplished. Depending on a dual-wavelength method or a coefficient ratio method, the absorption value of nicotine in solution was measured. Finally, nicotine amounts were calculated puff-by-puff.

Results: The method successfully realized the accurate detection of nicotine flux with low quantification limits (7.1 μg mL). Meanwhile, the method has high stability and reproducibility (RSD <10 %), and is suitable for monitoring the NF and NDS.

Significance: It has great potential for application in the evaluation of nicotine delivery efficiency. It fills the gap in the field of nicotine flux stability measurement and meets the monitoring needs of the industry and quality control for nicotine flux stability of e-cigarettes.