Percent Free Base Nicotine in the Tobacco Smoke Particulate Matter of Selected Commercial and Reference Cigarettes

Abstract

The available evidence suggests that most of the nicotine in mainstream tobacco smoke is in the smoke particle matter (PM) phase. Nicotine can exist in protonated and free base forms in the smoke PM, and alpha(fb) is the fraction of the PM nicotine that is in the free base form. Because only the free base form can volatilize from the smoke PM phase to the gas phase of an inhaled aerosol and because gaseous nicotine deposits rapidly in the respiratory tract (RT), the magnitude and rate of nicotine deposition in the RT will depend on alpha(fb). The types of values that alpha(fb) can assume in the PM of cigarette smoke aerosols have not been well-known. The conventional view has been that mainstream cigarette smoke PM contains relatively little free base nicotine so that the cigarette smoker must absorb nicotine mostly from deposited particles. A prior study concluded that because cigarette smoke is at "pH 5.3", there is very little free base nicotine in such smoke. A 1994 internal tobacco company document discusses the view that "smoke pH" values for cigarette smoke are "approximately 6.0". This work uses volatility-based measurements to provide determinations of equilibrium nicotine alpha(fb) values for mainstream smoke PM from selected cigarettes. The effective pH (i.e., pH(eff)) of the smoke PM from selected brands of commercial cigarettes was found to span a range of 6.0-7.8 (nicotine alpha(fb) = 0.01-0.36), with all pH(eff) values much larger than 5.3 and most larger than 6.0.

Metabolism and Disposition Kinetics of Nicotine

“…It has recently been proposed that the pH of cigarette smoke particulate matter is higher than previously thought, and thus, a larger portion of nicotine would be in the unionized form, facilitating rapid pulmonary absorption (Pankow, 2001). The effective pH values for particulate matter in various brands of cigarettes were measured to span a range of 6.0 to 7.8 (Pankow et al, 2003).…”

Reduced Nicotine Cigarettes: Smoking Behavior and Biomarkers of Exposure among Smokers Not Intending to Quit

“…Cigarettes deliver nicotine at a rate and in a manner of dosing that maximizes the bioavailability of nicotine and provides significantly greater consumer appeal than pharmaceutical or noncombustible tobacco products. Nonnicotine constituents also contribute to the addictive properties of cigarettes, including substances that minimize the irritation of inhaling smoke, as well as other pharmacologically active compounds (5,6). In most cases, these nonnicotine constituents either potentiate the positive effects or ameliorate the negative effects of nicotine administration (3).…”

Development and Initial Application of Low-Molecular Weight Organic Acids and Inorganic Ionic Species in Aerosol Particulate Matter via Ion Chromatography

“…14 The value of this fraction in tobacco smoke is dependent on the total ratio of acids to bases. There are naturally occurring acids in tobacco, such as acetic, formic, and propionic acid, which allow nicotine to be in its protonated and non-volatile form.…”