A rapid new analytical protocol was developed for the determination of aldehydes and ketones in exhaust gases from alcohol-fuelled motor vehicles equipped with three-way catalytic converters. The procedure involves collection of samples with two microimpingers (connected in series) containing an acid solution of 2,4-dinitrophenylhydrazine (2,4-DNPHi), recovery of the corresponding 2,4-dinitrophenylhydrazones (2,4-DNPHo) by retention on reverse phase microcolumns (Sep-Pak C18) and elution with dichloromethane or methanol. Separation and quantitation of the 2,4-DNPHo were done by reverse phase HPLC using methanol:water (57:43) as the mobile phase at l.OmL/min and absorbance detection at 365 nm. The results obtained in the recovery of formaldehyde and acetaldehyde from the exhaust of automobiles submitted to typical urban driving conditions indicate that the new analytical protocol compares favorably in terms of accuracy, precision, cost and speed of analyses when compared with binary solvent collection and liquid-liquid extraction procedures.
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