Grantee Research Project Results
Development of Aerosol Microchip Electrophoresis for Monitoring Atmospheric AerosolsEPA Grant Number: F08B10308
Title: Development of Aerosol Microchip Electrophoresis for Monitoring Atmospheric Aerosols
Investigators: Noblitt, Scott D.
Institution: Colorado State University
EPA Project Officer: Cobbs-Green, Gladys M.
Project Period: January 1, 2008 through December 31, 2008
RFA: STAR Graduate Fellowships (2009)
Research Category: Academic Fellowships
Aerosols are small (< 10 microns) solid or liquid particles that can stay suspended in the atmosphere due to their small size. Atmospheric aerosols represent significant unknowns in both climate and human health. Aerosols scatter sunlight, leading to reduced visibility and lower temperatures, and also affect rainfall patterns by modifying cloud formation. Aerosols interact differently with the human body than most other atmospheric compounds because their unique size allows deposition directly into the lungs, and this can lead to unexpected health effects. Current technology allows fast monitoring of aerosol number and/or size, but instrumentation for monitoring chemical composition is still lacking. Specifically, faster real-time monitoring techniques are needed because aerosols exhibit high variability with both time and location.Approach:
Current instruments are expensive ($50-500k), preventing their use in monitoring networks such as the US EPA IMPROVE program. The goal of my project is to develop a small, inexpensive ($5-10k), and fast instrument for measuring the chemical composition of atmospheric aerosols. I use microchip electrophoresis to measure aerosol chemical composition. This technique employs electric fields to separate chemicals based on their charge and size. It is fast (< 1 minute analyses), inexpensive, and portable. To sample the aerosols, I use a water condensation particle collector, also known as a growth tube. This device chills incoming particles and then condenses warm water onto them, increasing their mass for deposition into the microchip for chemical analysis.Expected Results:
Thus far, I have developed a new microchip separation for typical anions present in aerosols, and this method is capable of aqueous detection limits of 2 parts per billion (ppb). This method was utilized with the integrated instrument, and results were comparable to existing instrumentation, but the microchip obtained better time resolution. Completion of this instrument will permit aerosol monitoring on a faster time scale with a cheaper device. Employment in monitoring networks should be feasible, and modifications to the device to allow monitoring of other chemicals, more automated operation, and improved instrument performance are currently being pursued. Extensions to this technology could also allow for mobile aerosol monitoring or sensing of airborne pathogens.