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Collection efficiencies of an electrostatic sampler with superhydrophobic surface for fungal bioaerosols.

Han T; Mainelis G
Proceedings of the AAAR 28th Annual Conference, Minneapolis, Minnesota, October 26-30, 2009. Mount Laurel, NJ: American Association for Aerosol Research, 2009 Oct; :910
We recently developed a new sampling concept for determining exposures to airborne microorganisms at low concentrations. The electrostatic precipitator with superhydrophobic surface (EPSS) was shown to effectively collect airborne bacteria while achieving very high concentration rates. Here we analyzed the performance of this sampler with three commonly found fungal spores - Cladosporium cladosporioides, Penicillium melinii, and Apergillus versicolor - as a function of collecting droplet size, airborne fungal particle concentration, and sampling time. The fungal bioaerosols drawn into the EPSS were deposited on a narrow electrode (2.1 or 3.2mm) by the action of an electrostatic field and were then removed by a small (10 or 40 micro L) rolling water droplet. We used acridine orange epifluorescence microscopy (AOEM) to determine the total number of collected spores and the collection efficiency of the EPSS. Additionally, for a rapid quantification of collected fungal particle, we developed and applied an assay based on adenosine triphosphate (ATP) bioluminescence. At the sampling rate of 10 L/min and using 10 or 40 micro L collection droplet, the collection efficiencies ranged from 10 to 36% when airborne fungal concentration was approximately 10$^2/Liter - a range that could be comfortably counted using AOEM method. Collection efficiencies determined by the ATP method agreed well with those determined by the AOEM. Further, the collection efficiency with 40 micro L water droplet was found to be inversely proportional to the airborne spore concentration, likely due to spore hydroscopicity, and increased to 95% when spore concentration decreased to approximately 10/Liter. At such low aerosol concentrations, we were able to perform the testing only with the ATP-based method, but not using the AOEM which indicates utility of the ATP-based fungi analysis technique. Finally, for 10 and 40 micro L droplets we were able to achieve sample concentration rates of up to approximately 10$^5 at the sampling rate of 10 L/min.
Sampling; Exposure-levels; Air-samplers; Air-samples; Air-sampling; Airborne-particles; Microorganisms; Electrostatic-precipitation; Electrostatic-precipitators; Analytical-processes; Fungi; Statistical-analysis
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Proceedings of the AAAR 28th Annual Conference, Minneapolis, Minnesota, October 26-30, 2009
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Rutgers the State of New Jersey - New Brunswick
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