Toxic carbonyl compounds, including formaldehyde, malonaldehyde, and glyoxal, formed in mainstream cigarette smoke were quantified by derivatization—solid phase extraction—gas chromatography methods. Cigarette smoke from 14 commercial brands and one reference (2R1F) was drawn into a separatory funnel containing aqueous phosphate-buffered saline. Reactive carbonyl compounds trapped in the buffer solution were derivatized into stable nitrogen containing compounds (pyrazoles for β-dicarbonyl and α,β-unsaturated aldehyde; quinoxalines for α-dicarbonyls; and thiazolidines for alkanals). After derivatives were recovered using C18 solid phase extraction cartridges, they were analyzed quantitatively by a gas chromatograph with a nitrogen phosphorus detector. The total carbonyl compounds recovered from regular size cigarettes ranged from 1.92 mg/cigarette−1 to 3.14 mg/cigarette−1. The total carbonyl compounds recovered from a reference cigarette and a king size cigarette were 3.23 mg/cigarette−1 and 3.39 mg/cigarette−1, respectively. The general decreasing order of the carbonyl compounds yielded was acetaldehyde (1110–2101 μg/cigarette−1) > diacetyl (301–433 μg/cigarette−1), acrolein (238–468 μg/cigarette−1) > formaldehyde (87.0–243 μg/cigarette−1), propanal (87.0–176 μg/cigarette−1) > malonaldehyde (18.9–36.0 μg/cigarette−1), methylglyoxal (13.4–59.6 μg/cigarette−1) > glyoxal (1.93–6.98 μg/cigarette−1). © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 47–54, 2006.