Simultaneous on-line size and chemical analysis of gas phase and particulate phase of cigarette mainstream smoke.

This paper describes the combined set-up of on-line chemical analysis of gas phase by single-photon ionisation/resonance enhanced multiphoton ionisation-time-of-flight mass spectrometry (SPI/REMPI-TOFMS) and on-line particle size analysis by differential electrical mobility particle spectrometry (DMS 500) for the investigation of fresh cigarette mainstream smoke. SPI is well suited for the investigation of a great variety of organic species, whereas REMPI is highly sensitive for aromatic compounds. Gas phase measurements of filtered and unfiltered smoke are possible with the SPI/REMPI-TOFMS in order to determine the influence of the presence of particles on the chemical composition of the gas phase. Initial results are shown for the characterisation and comparison of three pure Virginia tobacco research cigarettes having filter ventilations of 0%, i.e. no filter ventilation, 35% and 70% ventilation. The three cigarette types are smoked under two different smoking regimes, a standard regime using puff parameters equivalent to the conventional International Standard Organisation regime and a more intense smoking regime. For the gas phase, qualitative puff-by-puff resolved yields of three selected compounds (acetaldehyde, phenol and styrene) are shown and compared. For particulate matter, particle number, count median diameter and total surface area are illustrated on a puff-by-puff basis. Yields of the chemicals analysed, puff number and surface area are in good agreement with the intensity of the smoking regime and the dilution of smoke by filter ventilation. However, gaseous compounds are influenced differently, depending whether an absolute particle filter is present or not, i.e. they can be totally removed (phenol), partially removed (styrene) or not affected (acetaldehyde). For particle analysis, the count median diameter decreases from puff to puff and is strongly dependent on the smoking regime and ventilation rate. Thereby, 0% ventilated cigarettes smoked under the intense regime result in the smallest count median diameters of ca. 180 nm, whereas 70% ventilated cigarettes smoked with a standard regime lead to the largest values of up to 280 nm. As particle diameter increases, particle number decreases as a consequence of increasing time for particle coagulation.