quantification of Free-Base and Protonated Nicotine in Electronic Cigarette Liquids and aerosol Emissions

Introduction:
This text discusses a study that aimed to develop a method for determining the proportion of free-base and protonated nicotine in electronic cigarette (ECIG) liquids and aerosol emissions. The study also investigates whether nicotine in ECIGs is present in more than one form, and whether measurements are affected by sampling media. The text presents a validated method for determining total, free-base (Nic) and protonated nicotine (Nich+) in ECIG liquids and aerosol emissions.

Key Points:

* The study developed an analytical method based on liquid-liquid extraction coupled with GC analysis to assess the respective amounts of Nic and Nich+.
* The method was first verified on ph-controlled solutions (5 < ph < 10) and then applied to several ECIG liquids and aerosols generated using a smoking machine.
* The method showed high repeatability and efficiency, and the results were in agreement with theoretical predictions based on measured ph of the standard nicotine solutions.
* ECIG liquids and aerosols contained both Nic and Nich+, and their relative proportions varied widely.
* Free-base nicotine was found to account for 18-95% of the total nicotine depending on the product in question.
* The study suggests that studies of nicotine delivery from ECIGs should account for the variation in nicotine partitioning across products.
* The study also demonstrates a convenient method for analyzing nicotine fractions in electronic cigarettes.

Main Message:
The study presents a reliable and validated method for determining the proportion of free-base and protonated nicotine in ECIG liquids and aerosol emissions. The study also highlights the importance of accounting for the variation in nicotine partitioning across products in studies of nicotine delivery from ECIGs. Overall, the study provides valuable information for the regulation of ECIG products and for understanding nicotine delivery, efficacy, and abuse potential from ECIGs.

El-hellani, ahmad, Rachel El-hage, Rima Baalbaki, Rola Salman, Soha Talih, alan Shihadeh, and Najat a. Saliba. “Free-Base and Protonated Nicotine in Electronic Cigarette Liquids and aerosols.” Chemical Research in Toxicology 28, no. 8 (august 17, 2015): 1532–37. https://doi.org/10.1021/acs.chemrestox.5b00107.