Time-resolved analysis of cigarette combustion gases using a dual infraredtunable diode laser system

An infrared spectroscopic technique has been developed to measure ammonia, ethylene, and formaldehyde in single puffs of whole cigarette smoke with mi llisecond resolution. Since formaldehyde levels in smoke decrease with incr easing ammonia levels, this effect was studied by simultaneous measurement of the two compounds during a puff. Ethylene was measured since it is inert and hydrophobic. The spectral lines chosen for quantitation were determine d to be linear with concentration and free from interferences from other sm oke constituents. The limit of detection for ammonia at 965.353 cm(-1) was 2 ng (80 ppbv) and for ethylene at 965.459 cm(-1) was 324 ng (8 ppm) in a p uff of 35 ml volume and 2 s duration. Others have reported that hydrazine i s present in smoke at 70 ppbv per puff using trapping and derivatization me thods. Attempts here to detect hydrazine in smoke without trapping and deri vatization were unsuccessful at the current limit of detection of 25 ppm in the 958 cm(-1) spectral region. This limit is due to interferences from un identified smoke components. The reactivity of hydrazine in smoke was deter mined by adding 520 ppm hydrazine to the smoke matrix, where 83% was consum ed in the first second of a three-second sample. (C) 2001 Elsevier Science B.V All rights reserved.