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 -dicarbonyl and , -unsaturated aldehyde; quinoxalines for -dicarbonyls; and thiazolidines for alkanals). After derivatives were recovered using C 18 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 À1 to 3.14 mg/cigarette À1 . The total carbonyl compounds recovered from a reference cigarette and a king size cigarette were 3.23 mg/cigarette À1 and 3.39 mg/cigarette À1 , respectively. The general decreasing order of the carbonyl compounds yielded was acetaldehyde (1110-2101 g/cigarette À1 ) > diacetyl (301-433 g/cigarette À1 ), acrolein (238-468 g/cigarette À1 ) > formaldehyde (87.0-243 g/cigarette À1 ), propanal (87.0-176 g/cigarette À1 ) > malonaldehyde (18.9-36.0 g/cigarette À1 ), methylglyoxal (13.4-59.6 g/cigarette À1 ) > glyoxal (1.93-6.98 g/cigarette À1 ).