Nuclepore filter collection with subsequent electron microscopy analysis for nanosized agglomerates (20-500 nm in mobility diameter) was carried out to examine the feasibility of the method to assess the personal engineered nanoparticle exposure. The number distribution of the nanoparticles collected on the filter surface was obtained by visual counting and converted to the distribution in the air using validated capillary tube models. The model was validated by studying the overall penetrations of nanoparticles (Ag and soot) with different agglomeration degrees through 1 μm pore diameter Nuclepore filters at different face velocities (2-15 cm/s). In the model, the effects of the maximum length of agglomerates on interception deposition and the dynamic shape factor on impaction deposition were taken into account. Results showed that the data of the overall penetration were in very good agreement with the properly applied models. A good agreement of filter surface collection between the validated model and the SEM analysis of this study was obtained, indicating a correct particle number distribution in the air can be converted from the Nuclepore filter surface collection and this method can be applied for quantitative engineered nanoparticle exposure assessment.
Bibliographical noteFunding Information:
Acknowledgments This work was supported by the NSF Grant (Award ID: 1056479) on ‘‘Real Time Measurement of Agglomerated or Aggregated Airborne Nanoparticles Released From a Manufacturing Process and Their Transport Characteristics’’. Financial support by the European Committee for Standardisation in the frame of mandate M/461 ‘‘Standardisation activities regarding nanotechnologies and nanomaterials’’ is acknowledged. The authors thank the support of members of the Center for Filtration Research: 3 M Corporation, Boeing Commercial Airplanes, Cummins Filtration Inc., Donaldson Company, Inc., Entegris, Inc., Hollingsworth & Vose Company, MANN ? HUMMEL GMBH, MSP Corporation, Samsung Electronics Co., Ltd, Shigematsu Works Co., Ltd, TSI Inc., and W. L. Gore & Associates, Inc., and the affiliate member National Institute for Occupational Safety and Health (NIOSH). Parts of this work were carried out in the Characterization Facility, University of Minnesota, a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org) via the MRSEC program. One of the authors, Heinz Fissan, acknowledges the support by the Institute of Energy and Environmental Technology (IUTA), Duisburg, Germany.
- Capillary tube model
- Engineered aggregates and agglomerates
- Exposure assessment
- Fractal dimension
- Nanoparticle size distribution
- Nuclepore filter