title: A new semivolatile aerosol dichotomous sampler.
abstract: This study reports the results of a numerical investigation and an experimental study on a round nozzle virtual impactor (VI) operated in two different modes. The newly proposed sampler, the semivolatile aerosol dichotomous sampler (SADS), was studied to overcome some of the problems of existing personal sampling methods such as evaporative loss during filter sampling. The main difference between VIs and the SADS was the inverted flow ratio between the major flow and the minor flow. Sampling in the SADS settings gives a lower cutsize in both numerical simulations and experimental results. Whereas the 50% separation efficiency for a VI occurred in numerical simulations when the square root of Stokes number equaled 0.97, the 50% efficiency for the same sampler run in the SADS settings occurred when the square root of the Stokes number was 0.27. The back pressure on each flow direction was studied and greater pressure drop was observed through the vapor flow in SADS settings. Sampling using a SADS was more effective than traditional filter methods because of its smaller cutsize, instant separation of vapor from particles and reduced particle losses.
authors.affiliation: Division of Environmental Health Sciences, School of Public Health, University of Minnesota, Minneapolis, MN, USA. kim.seungwon@gmail.com
authors.forename: Seung Won
authors.initials: SW
authors.lastname: Kim
authors.forename: Peter C
authors.initials: PC
authors.lastname: Raynor
mesh_terms: D000395:Air Pollutants, Occupational / Q000032:analysis*; D003198:Computer Simulation; D004784:Environmental Monitoring / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D006801:Humans; D007221:Industry; D008962:Models, Theoretical; D052638:Particulate Matter / Q000032:analysis*
chemical_list: D000395:Air Pollutants, Occupational; D052638:Particulate Matter