Introduction JUUL is an electronic cigarette (ECIG) with a compact form factor. It is prefilled with a liquid that is advertised to contain a high concentration of nicotine salt. JUUL commands 50% of the US ECIG market share, and its wide popularity with underage users has triggered unprecedented actions by the US FDA. Apart from its nicotine salt-containing liquid and compact form, a salient advertised design feature is a control circuit that limits the heating coil temperature, presumably reducing unwanted toxicants. In this study, several tobacco-flavoured JUUL devices were reverse engineered, and their aerosol emissions were studied.
Methods Total nicotine and its partitioning (freebase and protonated), propylene glycol/vegetable glycerin (PG/VG) ratio, and carbonyls were quantified by gas chromatography (GC) and high performance liquid chromatography (HPLC). The temperature control functionality of JUUL was investigated using a temperature-controlled bath in which the coil was submerged.
Results The liquid nicotine concentration was found to be 69 mg/mL, and the liquid and aerosol PG/VG ratio was found to be 30/70. In 15 puffs, JUUL emitted 2.05 (0.08) mg of nicotine, overwhelmingly in the protonated form. Carbonyl yields were significantly lower than those reported for combustible cigarettes, but similar to other closed-system ECIG devices. The heating coil resistance was 1.6 (0.66) Ohm, while the maximum power delivered by the JUUL device was 8.1 W. The control circuit limited the peak operating temperature to approximately 215C.
Conclusions JUUL emits a high-nicotine concentration aerosol predominantly in the protonated form. JUUL’s nicotine-normalised formaldehyde and total aldehyde yields are lower than other previously studied ECIGs and combustible cigarettes.
- electronic nicotine delivery devices
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Contributors ST, RS, REH, EK, NK, AE-H, NS and AS: conception and design of research. RS, EK and REH: performed experiments. ST, RS and AS: analysed the data. ST and AS prepared figures. ST and AS: drafted manuscript. ST, RS, REH, EK, NK, AE-H, NS and AS: edited, revised and approved final version of manuscript.
Funding This work was supported by the National Institute on Drug Abuse of the National Institutes of Health (grant number P50DA036105 and 2U54DA036105-06) and the Center for Tobacco Products of the US Food and Drug Administration.
Disclaimer The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or the Food and Drug Administration.
Competing interests AS is a paid consultant in litigation against the tobacco industry and is named on a patent application for a device that measures the puffing behaviour of electronic cigarette users.
Patient consent Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Correction notice This article has been corrected since it was published Online First. Additional funding information has been added.