Partitioning and ammonium replacement of nicotine and basic gases to particulate matter

Henry Jay Colby VI

doi:10.17918/00001914

Airborne particulate matter (PM) is a pollutant with effects on human health, environmental health, climate, and meteorology. PM size, composition, formation, modulation, sinks, and sources are all necessary considerations in understanding their full impact on our planet and our health. The effect PM has on indoor environments is a growing field of study as people in the developed world spend most of their time indoors. For this reason, it is extremely important to consider indoor sources, transport, modulation, and composition of PM. One substantial source of indoor air pollution is tobacco smoke. The use of combustion tobacco products dramatically increases indoor concentrations of PM and gas-phase toxins like benzene, carbon monoxide, and formaldehyde among dozens of others. These toxins can deposit onto surfaces and have long-term impacts on indoor air, and these long-lived pollutants are known as third-hand smoke (THS). In addition to combustion tobacco products, the recent introduction of electronic cigarettes (e-cigs) to the market has now been a target of investigation regarding their impact on human health and their impact on the surrounding air quality. The research presented herein investigates the impact that deposited e-cig emissions have on air quality and in particular the impact that e-cig residues have on PM using numerous analytical tools, including aerosol mass spectrometry (AMS), proton transfer reaction mass spectrometry (PTR-MS), and cavity ringdown spectrometry (CRDS). It was identified that deposited e-cig emissions would act as a source for nicotine and a common e-cig solvent, vegetable glycerin (VG), which was shown to evaporate from surfaces and partition to lab generated ammonium sulfate particles even after being deposited days earlier. However, there were components identified in primary e-cig emission that did not partition to lab generated particles; these include another common e-cig solvent, propylene glycol (PG), benzoic acid (BA), and cadmium. Through further investigation into the process of nicotine-particle partitioning we found that the process of nicotine partitioning to ammonium sulfate particles resulted in ammonium replacement. This indicates that nicotine can partition and replace ammonium as the conjugate acid of sulfate and release the former ammonium as ammonia gas. The replacement of ammonium by nicotine revealed an important implication for the traditional analysis of the ammonium balance that had not been previously investigated. Since the ammonium balance analysis traditionally only includes inorganic ions to calculate the particle ion balance, excluding organic ions, such as protonated amines (aminiums), would result in a large deficit in the balance. When the mole fraction of nicotine was included in the ammonium balance, the deficit was almost completely rectified in our experiments. The impact of aminiums on the ammonium balance was then retroactively applied to field studies that were monitoring the modulation of outdoor particles when they travel indoors. Our investigation found that when the amine content indoors is high, the change in the ammonium balance can be drastic and needs to be accounted for. In one study, incorporating aminium ions increased the balance significantly from 0.21 to 0.84, where 1.00 is fully charge balanced. However, even in a study when indoor amine concentrations were not expected to be high, including aminium considerations in the ammonium balance increased the ammonium balance from 0.42 to 0.56. This finding emphasizes the impact that indoor gas-phase amines can have on particle composition, which is significant for understanding particle dynamics, chemical transport, and indoor air in general.

Partitioning and ammonium replacement of nicotine and basic gases to particulate matter

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Partitioning and ammonium replacement of nicotine and basic gases to particulate matter

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