Performance of a 2,4-DNPH coated annular denuder/HPLC system for formaldehyde monitoring in air

The performance of annular denuders coated with 2,4-dinitrophenylhydrazine for collection of atmospheric HCHO has been evaluated by HPLC/UV analysis o f samples coming from laboratory tests and field experiments. A number of p arameters, such as collection efficiency at varying air humidity, detection limit, operative capacity and temporal self-consistency have been investig ated to optimize the denuder behaviour under different weather conditions a nd to obtain short-term concentration profiles of HCHO. Deviations between measurements made simultaneously by the DNPH denuder method and differentia l optical absorption spectrometry (DOAS) have been found to average approxi mately 30 % in the 0-5 ppb HCHO concentration range.