Air sampling of aerosol and gaseous pesticides

Rotating disk impactor (RDI) technology was investigated for the collection of separate liquid and vapor phases of airborne pesticides and simulants. An RDI collected from 90 to 99% of potassium bromide, clomazone, and malath ion aerosols when directly coupled to a nebulizer that produced drop diamet ers ranging from 2 to 20 mu m. The RDI also collected over 95% of the mass of clomazone and malathion vapors when connected to a vapor generator, ther eby limiting any phase partitioning of the sample. Vapor collection was att ributed to the exposure, affinity, and solubility between the RDI collectio n well liquid and sampled chemical. However, the RDI sampling system has me rit and further research should prioritize ways to minimize inadvertent col lection of vapor. Ethylene glycol was selected as the RDI collection well l iquid based on reduced volatile loss of the collection liquid for sampling periods observed up to 7 h and mean recovery efficiencies of 86 and 87% for clomazone and malathion, respectively. Also, n-decane was a suitable colle ction well liquid when direct injection into the analytical instrument was possible, since n-decane was miscible with a number of solvents used for pe sticide extraction. Conventional air sampling media that may be used in ser ies with the RDI, instead of delicate bubblers, were evaluated for the reco very of a selected pesticide. Clomazone recoveries for a 15-min, 1 L min(-1 ) airflow rate from glass fiber filter, polyurethane foam, a fritted imping er, and a multi-element OSHA versatile sampler (OVS) were 66, 92, 84, and 7 3%, respectively.