Innovative methodology based on thermo-denuder principle for the detection of combustion related solid particles or high boiling point droplets: Applications to cigarette and the Tobacco Heating System THS 2.2

Authored by  P Pratte, S Cosandey, C Goujon-Ginglinger

Published in Journal of Aerosol Science    

Combustion-related solid particles are known to potentially cause adverse effects on human health. In the scope of developing further the understanding on how combustion-related particles trigger biological responses in human, collecting them efficiently is key prior their characterization. To collect and characterize them from an aerosol, a methodology using a Dekati thermo-denuder operated at 300°C was established. The current work addresses the performance of the method by assessing its removal efficiency based on determined aerosol penetration for model solid particles and liquid droplets. The solid particle penetration was measured to be 79.4 ± 7.3% linked to the aerosol wall losses. To evaluate the ability of the thermo-denuder to remove liquid droplets, aqueous solutions of propylene glycol and glycerine were nebulized. From the measurements, the largest penetration value was measured to be 2.7 ± 1.0%. As a result, the methodology limit of detection (Lodge and Chen, 1988) was found to be 3.7% and the lower limit of quantification (LLOQ) 11.1%. Moreover, further experiments were conducted to ensure that liquid-coated solid particles could be distinguished from non-evaporated droplets to avoid data misinterpretation. To this end, ∼70 nm-NaCl particles were coated with glycerin reaching a size diameter on the order of the micron. The experiments showed that the layer of glycerin-coated NaCl was removed entirely when passing through the thermo-denuder for the submicron size range. As an application of the methodology, the 3R4F reference cigarette smoke and Tobacco Heating System2.2 (THS 2.2) mainstream aerosol were tested in the thermo-denuder. The data demonstrated that for 3R4F mainstream smoke, solid particles or high boiling point droplets were quantified far above the LLOQ (7.5 x 109particles for LLOQ, ∼1012 particles quantified for 3R4F mainstream). On the opposite, for THS 2.2 mainstream aerosol, the penetration was overlapping with the LLOQ within the experimental uncertainty. According to the current work and former published data, during the use of THS2.2, no combustion-related particles were observed. To conclude, the thermo-denuder technology is appropriate to detect/quantify solid particles or/and high boiling point droplets when combustion processes take place or for condensable aerosols.