AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Environmental Particle Collector and Detector System for Continuous Sampling of Ultrafine Aerosols
MARIA D. KING, Victor Ugaz, John Haglund, Ray Pierson, Yassin Hassan, Texas A&M University
Abstract Number: 197 Working Group: Aerosol Nucleation: From Clusters to Nanoparticles
Abstract Environmental exposure to aerosolized particulate matter less than 10 micrometer aerodynamic diameter is widely associated with adverse respiratory and cardiovascular health effects. Despite their high toxicity and mutagenic potential, few existing methods are capable of sampling and characterizing large airspace volumes for extended periods of time. We have established a real time in-line collection and detection method for nanosize aerosol particulates. Different concentrations of Al$_2O$_3 nanoparticle suspensions were aerosolized in a laboratory flow cell and collected with the low cutpoint WWC at 200 L/min using 0.01 % Tween-20. The collected WWC effluent was then co-injected into a microchannel with an aqueous 0.033 mg/mL fluorescein solution. A relatively linear concentration dependence of interfacial fluorescence is observed up to ~1 wt%, beyond which the intensity reaches saturation. Decreasing flow rate increases the intensity due to increased residence time for complexation. The WWC results display a clear correlation between nanoparticle concentration and fluorescence intensity that is in good agreement with the control suspensions (comparable concentrations but not aerosolized and collected by the WWC), verifying the potential for our microchannel-based method to enable continuous nanoparticle detection. Output liquid flow rates from the WWC of 0.04 – 0.2 mL/min are within the bounds of our experiments. Scanning Mobility Particle Sizer (SMPS) analysis confirmed that we were able to easily detect the lowest environmental particle concentration of ~200 microgram/meter$^3 (4 – 160 nm particle size range). Samples taken before and after WWC collection were also analyzed using a Nanosight system, which confirmed that the post-collection size distribution in the WWC did not deviate significantly from that of the aerosolized material. Each hydrosol sample from the WWC with the 102 mm reference filter suspensions was quantitated by gravimetry and inductively coupled mass spectrometry (ICP-MS) for Al$_2O$_3 content. We observed high levels of nanoparticle recovery (~75%) in all tests.