Development of an automated monitoring system for various gas-phase organic carbonyls in ambient air

An automated monitoring system for various C₁ to C₅ gas-phase organic carbonyls in ambient air is described. The system consists of a parallel plate diffusion scrubber (PPDS), which is coupled with a high-performance liquid chromatography–ultraviolet (HPLC–UV) system using an automated injection valve. Compared with an annular diffusion scrubber (DS) employed so far for gas-phase carbonyl monitoring, PPDS shows an improved collection efficiency for formaldehyde, acetaldehyde, propionaldehyde, and acetone with >97% at an airflow rate of 0.5?L/min. High gas–liquid concentration ratios of PPDS and an optimised HPLC–UV system allow limits of detection (LOD) in a range of 80–500?pptv. A low liquid hold-up volume of the PPDS results in a short response time of about 10?min. Additionally, the optimised analysis time for 13 carbonyl compounds containing calibration standard enables brief measurement intervals of 25?min. The developed PPDS–HPLC system shows its reliability from urban site monitoring in Seoul, South Korea.