A Unified Smoking-Automated Calorimetric System for the Analysis of the Gas Phase of Cigarette Smoke and its Application to the Determination of Hydrogen Sulfide

A system has been developed wherein the gas phase produced on smoking a cigarette through a Cambridge pad is analysed, on a puff-by-puff basis, for a desired component using automated colourimetry. The system consists of an AutoAnalyser I and a simple, 1-port smoking machine. The continuous gas stream from the smoking machine, either gas phase or intervening air, is passed concurrently with a stream of absorbing solution through a glass coil. Following passage through the coil, the solution is separated from the gas stream and introduced into the AutoAnalyser for continuous measurement of the concentration of the absorbed component. The entire system is calibrated using standard gas mixtures puffed in the same manner as the cigarette. The puff profile is essentially rectangular. Chief benefits expected from use of this system include the ability to obtain puff-by-puff measurements, a minimum time for reaction to occur in the gas phase and essentially no sample handling other than smoking the cigarette. The system has been utilized for the determination of hydrogen sulfide in gas phase using 0.1 N NaOH as the absorbing solution and the "methylene blue" colourimetric reaction. Results obtained on a variety of commercial U.S. brands ranged from 18 to 50 µg of H₂S per cigarette, similar to results reported by other investigators using wet chemical methods. The accuracy of the results is supported by recovery tests wherein gaseous H₂S added to the gas phase is completely recovered. The average relative standard deviations obtained with 11 U.S. commercial or reference cigarette samples using random selection of the cigarettes is 10.8 % for µg of H₂S per cigarette and 8.8 % for µg of H₂S per puff for a single cigarette. The basic system is thought to be applicable to the determination of a number of other components in gas phase.