Influence of relative humidity and gaseous ammonia on the nicotine sorption to indoor materials.

UNLABELLED: Sorption of nitrogen-containing organic constituents of environmental tobacco smoke may be influenced by ammonia, a common indoor gas, and relative humidity (RH). We quantified sorption kinetics and equilibria of nicotine with stainless steel, cotton-polyester curtain, and polypropylene carpet at 0%, 50%, and 90% RH and in the presence of ammonia using a 10-l stainless steel chamber. Nicotine was introduced into the chamber by flash evaporating 50 μl of pure liquid. Kinetic sorption parameters were determined by fitting a mass balance model to experimental results using a nonlinear regression. Results show that an equilibrium partition coefficient, k(e) , of nicotine tended to increase as the RH increased for the curtain and carpet. Adsorbed water may contribute to an increase in available sites for nicotine sorption on the surface. In the presence of 20- and 40-ppm NH(3) , the values of k(e) for carpet were decreased by 14-40% at 50% and 90% RH, but the effect of NH(3) was not observed at 0% RH. The values of k(e) ranged from 54 to 152 m. Our findings indicate the relative importance of nicotine sorption to surfaces is dependent on the relative humidity and the presence of ammonia. PRACTICAL IMPLICATIONS: This research demonstrates that relative humidity and gaseous ammonia can influence nicotine sorption to common indoor surfaces, i.e., curtains and carpets. Increasing the relative humidity from dry to modest appears to enhance the sorptive capacity. Presence of the typical range of gaseous ammonia concentrations can reduce the nicotine sorption in a humid environment but does not affect the sorptive capacity in the absence of added water. Thus, studies on the dynamic sorption of other alkaloids or amine constituents of environmental tobacco smoke to indoor surfaces should consider the impact of water vapor concentration because of the interaction of water with the surface and sorbates. Furthermore, the mixture of gaseous amines may participate in adsorption site competition.