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Quantitative FTIR analysis of gas phase cigarette smoke.
A new method, using Fourier transform infrared spectroscopy (FTIR), was developed for the simultaneous determination of nitrogen dioxide and nitric oxide in gas phase cigarette smoke and in model systems. The FTIR method also allows the simultaneous determination of other components.; The method uses multivariate least-squares regression analysis, that allows simultaneous quantitation of several components even in the presence of overlapping peaks, and fast data acquisition for kinetic analysis. For the preparation of the gas mixtures an apparatus that uses mass flow controllers, check-valves, and ground glass joints was constructed. This apparatus gives very exact metering, allowing the preparation of mixtures of precise concentrations, reducing the variations in the results between replications of experiments.; Using the developed method, model systems containing mixtures of nitric oxide/air with isoprene, methanol, acrolein, and acetaldehyde were studied using concentrations similar to those found in gas phase cigarette smoke. The "steady state" mechanism for the production of free radicals in gas phase cigarette smoke was substantiated, and a more realistic model for the continuous formation of free radicals in gas phase cigarette smoke was proposed. The concentrations of nitric oxide and nitrogen dioxide in the new proposed model (a mixture of nitric oxide, air, methanol, and isoprene) follow time courses that duplicate very closely those found for the same components in gas phase cigarette smoke.