Abstract:
:The wide pH range reported for electronic cigarette (ECIG) liquids indicates that nicotine may be present in one or more chemical forms. The nicotine form affects the bioavailability and delivery of nicotine from inhaled products. Protonated nicotine is normally associated with counteranions in tobacco products. The chemical and physical properties of counteranions may differently influence the nicotine form and emissions in ECIG aerosols. In this study, we examined how these anions influence nicotine emissions and their evaporation behavior and potential decomposition during ECIG operation. ECIG liquid solutions with equal nicotine concentration and pH but different counteranions (formate, acetate, and citrate) were prepared from analytical standards to assess the effect of the counteranion on nicotine partitioning. High performance liquid and gas chromatography methods were developed to determine the counteranions and the two protonated (NicH+) and free base (Nic) forms of nicotine in commercially available and standard solutions of ECIG liquids and aerosols. In commercial samples, acetate and citrate anions were detected. In standard solutions, both formate and acetate ions were found to evaporate intact, but citrate ion decomposed into formic acid and other products. This study also shows that the identity of the counteranion has no effect on total nicotine emission from ECIG in agreement with previous reports on tobacco cigarettes. However, the partitioning of aerosolized nicotine into NicH+ and Nic is anion-dependent even when the parent liquid pH is held constant. These results indicate that the anions found in a given ECIG product may influence the nicotine delivery profile to the user by enriching aerosols with free-base nicotine as in the case of polycarboxylic acids such as citric acid.
journal_name
Chem Res Toxicoljournal_title
Chemical research in toxicologyauthors
El-Hellani A,El-Hage R,Salman R,Talih S,Shihadeh A,Saliba NAdoi
10.1021/acs.chemrestox.7b00090subject
Has Abstractpub_date
2017-08-21 00:00:00pages
1577-1581issue
8eissn
0893-228Xissn
1520-5010journal_volume
30pub_type
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