Application of a Diffusion-denuder Method for the Investigation of the Effects of ‘Smoke pH’ on Vapor-phase Nicotine Yields from Different Types of Cigarettes

The potential effects of smoke pH on vapor-phase nicotine, or unprotonated nicotine, were investigated using a diffusion denuder method selected for its ability to quantitatively monitor vapor-phase nicotine in the presence of smoke particulate. For the purpose of this paper, the pH of the water-soluble fraction of mainstream cigarette smoke will be referred to as ‘smoke pH'. In this study, samples with different construction parameters affecting smoke pH were analyzed for percent vapor-phase nicotine. The smoke pH values ranged from 5.87 to 7.79. Percent initial vapor-phase nicotine values ranged from 0.4% to 1.5%. The range of the vapor-phase nicotine values for this study was (a) independent of smoke pH and (b) potentially dependent upon cigarette construction. In a second experiment, cigarettes with the same construction were used to repeat the analysis, thus eliminating construction as a variable. The tobacco was treated with varying levels of urea to give a range in smoke pH from 6.47 to 7.15. The determined initial vapor-phase nicotine values ranged from 0.4% to 2.1% of the total mainstream smoke nicotine. This variation was independent of smoke pH. It was determined in this study that (a) the maximum initial vapor-phase nicotine delivered to mainstream smoke was 2.1% of the total nicotine delivered for our cigarette samples and (b) the delivery of the unprotonated nicotine to mainstream smoke was not meaningfully affected by changes in smoke pH within the range studied.