Particle size measurement of electronic cigarette aerosol with a cascade impactor

Measuring the aerosol particle size of electronic cigarettes can be particularly challenging due to the volatile and dynamic nature of these aerosols. In particular, electronic cigarette aerosol particle size measurements may be convoluted by evaporation due to the high dilution ratios and coagulation when there are long residence times between sampling and measurement. To address these measurement issues, we have developed a particle size measurement system using a low flow cascade impactor with a sampling system that is capable of generating a puff on an e-cigarette and directly introducing the aerosol into the inlet flow of the impactor. The system has been used to investigate factors that may affect the aerosol size distribution, including puffing conditions, carrier composition and device construction. It was found that decreasing the puff flow rate from 2 to 0.5 L/min at a constant puff duration of 5 s, the mass median aerodynamic diameter (MMAD) of the aerosol size distribution increased from 0.5 to 1.1 µm. Increasing the mass delivery from 0.67 to 6 mg/5 s puff also resulted in increasing MMAD from 0.48 to 0.87 µm. Furthermore, the addition of a small amount of glycerin (1% by weight) to a propylene glycol based flavor formulation caused a decrease in the MMAD, while the other factors studied did not have a significant effect on the MMAD.Copyright © 2020 American Association for Aerosol Research