Measurement of Airborne Carbonyls with Pentafluorophenyl Hydrazine (PFPH)-Coated Tenax Tube using an Integrated Automatic Sampler in a Rapid Developing City in Pearl River Delta (PRD) Region, China

Abstract

Airborne carbonyls can be formed from primary and secondary sources which are widespread in the environments. Their abundances are always related to the degree of capitalization of a city or area. More sensitive measurement of active airborne carbonyls (e.g., formaldehyde and acetaldehyde) is thus critical to interpret their roles in the atmosphere. In this study, an observation was conducted in a rapid development city of Huizhou, where located in Pearl River Delta (PRD) Region in southern China. Monocarbonyls and dicarbonyls were collected onto pentafluorophenyl hydrazine (PFPH)-coated Tenax glass tubes by a modified automatic carbonyl sampler (ACS), which is originally adopted for sampling with default 2,4-dinitrophenylhydrazine (DNPH) cartridges. The tubes were analyzed by thermal desorption (TD)-gas chromatography/mass spectrometry (GC/MS) method. The results show that the collection efficiencies for both target carbonyls were consistent between a regular sampler and the ACS at a flow rate of 100 ml/min, demonstrating that the reliability and feasibility on the application of ACS for the carbonyls collection with the PFPH-coated tubes. The mean molar ratio of formaldehyde to acetaldehyde (1.17) in Huizhou suggests that the primary emission source was dominant in the city. According to the diurnal variations of the carbonyls, primary pollutants [e.g., nitrogen dioxide (NO2,) and sulfur dioxide (SO2)] and secondary pollutant [e.g., ozone (O3)], active carbonyls could be produced from both primary and secondary sources in daytime. Vehicle emission is expected to be more dominant in rush hours (i.e., early morning and evening). The peaks of formaldehyde around noontime were mainly attributed to increases of atmospheric photo-oxidation of other organics. The work indicates the advantages of using the PFPH-coated tubes for determination of diurnal variation on the atmospheric carbonyls with an aid of less labor-intensive automatic sampler.