Tobacco Documents Online

301 III. TRAPPING AND DETERMINATION OF ORGANIC GAS PHASE CONSTITUENTS OF CIGARETTE SMOKE - S. G. Zeldes and A. D. Horton Introduction. Bioassay of tobacco smoke by chronic inhalation exposure permits the exposure of experimental animals to non-condensible, bioactive constituents in the gas phase. In order to more fully describe the biolog- ical impact of the smoke, concentrations of such constituents in the exposure atmosphere should be quantified. For on-site monitoring and description of the gas phase exposure, we have relied on the concentrations of carbon monoxide and carbon dioxide as indicators of the overall dose of the vapor phase con- stituents. However, because of machine-to-machine variations and differences in exposure ward conditions, CO and CO` concentrations may not be completely indicative of total gas phase exposure. To this end, we have been developing sampling and trapping techniques for organic volatiles in tobacco smoke which may be potentially applicable to on-site (bioassay laboratory) sampling and off-site analysis. Trapping and retention of volatile, reactive organic compounds from concentrated atmospheres is by no means straightforward. The traps must be small, portable, and must be able to store trapped constituents for several days without aging. Here, we briefly summarize work completed on Tenax trapping of organic volatiles from the gas phase of cigarette smoke. In the coming year, we intend to field test this concept, once these procedures have been validated for use under the relatively high air flow conditions required to effectively withdraw smoke from the cannula exit of the dog ,~ exposure systems. A reprint of a publication from this work is attached following for those seeking more detail. Method. The trap consists of a 5 mm i.d. Pyrex glass tube filled with approximately 2 ml of Tenax-GC, a porous poly-p-2,6-diphenylphenylene oxide.

302 While Tenax is a highly adsorptive polymer, it has the disadvantage of a relatively low capacity. Thus only®fractions of the total puffs of a ciaa- rette can be stored on a single Tenax trap. The trap is attached to a single port smoking machine with a low volume sampling loop. The system is designed so that about 1% of the volume of each puff is routed through the trap. For efficient retention of gas phase constituents, flow through the trap is kept to a maximum of six bed volumes (6 X 2 ml = 12 ml) per minute. Following sampling, the tube can be capped and stored for later analysis. Analysis consists of placing the tube in the cold injector block of a cryothermal gas chromatograph. While the injector block is heated, the trap is back flushed with carrier gas and released volatiles are condensed on the cold (-70°C) head of the GC column. When desorption is completed, the column is warmed and individual components are eluted. Acetaldehyde, isoprene, and acrolein have been quantitatively determined by this method, and many other constituents exhibit the potential for quantification. Traps have been stored for up to three days with no apparent loss of constituents, but more validation work must be completed before this observation has been completely confirmed. This method of trapping and retention of constituents appears applicable to the problem of off-site analysis of labile, volatile organic materials. Methods will be investigated for this application during the coming year.