Microchip Electrophoresis Coupled to a Miniature Cloud Condensation Nuclei Collector for Online Monitoring of CCN Chemistry

SCOTT D. NOBLITT (1,2), Jeffrey L. Collett, Jr. (1), Charles S. Henry (1), Gregory C. Roberts (2)

(1) Colorado State University, Fort Collins, (2) Scripps Institute of Oceanography, La Jolla

     Abstract Number: 761
     Last modified: May 14, 2010

Abstract
Microchip electrophoresis (MCE) offers a promising new method for monitoring the chemical composition of aerosols. This technology possesses many advantages over conventional equipment, including smaller instrumentation, shorter analysis times, and the ability to make measurements from small liquid volumes. These attributes make MCE an attractive option for monitoring the chemistry of particles activated by cloud condensation nuclei (CCN) collectors because collection flow rates are very low (< 0.1 L/min), resulting in the deposition of very low aerosol masses. Here, we present the coupling of MCE to a miniature CCN collector for online monitoring of CCN chemistry. The outlet stream of the CCN system inertially impacts wetted CCN particles into a buffer-filled sample reservoir on a microchip for immediate electrophoretic analysis, which requires < 1 minute per run. Currently, the system collects aerosols at ~50 mL/min and deposits them into ~20 microliters of solution to provide detection limits of ~0.2 micrograms per cubic meter with 10 minutes of sampling. Concentrations are measured via differential analysis, and detection limits are inversely proportional to collection time, which can extend over an hour. Here, we show the technical aspects of the prototype instrument as well as data from preliminary ambient sampling.