Electronic cigarettes (EC) have the potential to pose reduced risk to the consumer compared to combustion products, due to the absence of toxic byproducts of combustion. These products function by heating and vaporizing e-liquid at lower temperatures. One concern related to heating temperature in EC is the elevated production and subsequent exposure to toxic carbonyl compounds (formaldehyde, acetaldehyde, acrolein, etc.), particularly in devices that do not directly control coil temperature. By contrast, the JUUL device is a closed system with temperature regulation designed to maintain temperature consistency and minimize the generation of degradation products.

The purpose of this study is to correlate heating coil temperature to the concentration of carbonyl compounds present in the aerosol delivered by a JUUL device.

The methods used were as follows:

1. Prototype JUUL devices of different coil temperature settings are created by alteration of the device firmware.
2. Total particulate mass (TPM) as a function of coil set temperature are determined under fixed puffing conditions.
3. E-liquid aerosol composition, total nicotine, propylene glycol, and glycerol collected during TPM measurements are quantified by gas chromatography.
4. Aerosol samples are collected in impingers with DNPH solution and analyzed for carbonyls via high performance liquid chromatography-mass spectroscopy.
5. Atomizer temperatures are measured simultaneously by infrared (IR) thermography and real-time electrical resistance of the heating coil wire.

TPM, carbonyl analysis, and IR thermography were executed using heating coil temperature set points of 237 °C to 417 °C centigrade. TPM and carbonyls increase with the coil temperature. IR thermography measurements corroborate with heating coil electrical resistance measurements.

These findings suggest that the carbonyl yields from JUUL under nominal operating coil temperatures are significantly below levels in combustion cigarettes and at the low end of published data on e-cigarettes. Higher temperatures can produce more carbonyls, suggesting the importance of temperature control mechanisms within EC hardware.