Microchip Capillary Electrophoresis for On-Line Measurement of Inorganic Aerosols

The U.S. Environmental Protection Agency has identified the need for continuous monitors that can operate unattended and provide real-time data on the concentration of the major chemical components of PM2.5, defined as particles with diameters of less than 2.5 µm. The chemical composition of fine airborne particles is needed to identify sources, understand formation mechanisms, and further elucidate exposures and health effects. Aerosol Dynamics, Inc., proposes a compact, inexpensive, and sensitive instrument using capillary electrophoresis (CE) mounted on a microchip. Ambient particles are deposited directly on the CE chip by means of humidification, growth, and impaction. Ambient particles are extracted directly in a small aqueous volume for the in situ CE analyses of particle-bound inorganic ions. Both cations and anions will be determined. This "laboratory on a chip" technique will provide online, time-resolved quantification of a suite of PM2.5 inorganic ions found in ambient aerosol. This approach will provide a 5-minute time resolution for ions with detection limits of 10 ng/m3 or better. Commercial applications include monitoring in homes, schools, and offices in addition to central monitoring sites. The CE technique is inherently far more cost-effective than current approaches.