The development of an automated method for the simultaneous determination of nitrogen oxides, aldehydes and ketones is described. All components are sampled together by means of impingers, which are filled with an acidified solution of DNPH in acetonitrile. The corresponding derivatives are separated and quantified by reversed-phase HPLC with UV detection at 300 nm or at 345 nm. Using this reproducible method calibration curves with a correlation coefficient of 0.999 could be obtained. The method was validated by means of several field tests, measuring candle smoke and cigarette smoke.