Wet Cyclone Sampling for Time-Resolved Molecular Analysis of Organic Aerosols: Performance Evaluation and Application to Incense Smoke

Abstract. This study was motivated by the need for a practical alternative to conventional filter sampling that retains its ease of field deployment while providing improved temporal resolution. A condensational growth wet cyclone sampler was developed and characterized for time-resolved collection of organic aerosols and coupled with liquid chromatography mass spectrometry for molecular analysis of aerosol composition. The sampler combines the condensational growth chamber of a particle-into-liquid sampler with a miniature wet cyclone, where the grown droplets are collected by centrifugal deposition into a continuously wetted liquid vortex. Collection performance of the sampler was optimized using polydisperse oleic acid particles as a representative of water-insoluble organic aerosols. Under optimized conditions, the collection efficiency of oleic acid particles reached 64.5±8.3%, with remaining losses attributed primarily to liquid entrainment into the gas exhaust and compound-specific retention within the collection pathway. Collection efficiency was relatively insensitive to the initial particle size distribution over the range examined, as condensational growth produced droplets sufficiently large for effective cyclone collection. The sampler was subsequently applied to incense smoke, where its recovery of molecular components was compared with conventional filter sampling under the same mass-spectrometric analysis. The cyclone samples captured major molecular features observed in paired filter samples and also recovered molecules extending to relatively high carbon numbers. Sequential collection further resolved the temporal evolution of particulate diethyl phthalate, a major component of incense smoke. These results demonstrate that the condensational growth wet cyclone broadens liquid-based collection to a wider range of particle-phase constituents and provides an accessible interface for time-resolved molecular characterization of organic aerosols.