HR: 0800h
AN: P51D-0962    [Abstracts]
TI: Advances in Automation and Throughput of the Mars Organic Analyzer Microchip Capillary Electrophoresis System
AU: * Haldeman, B J
EM: haldeman@me.berkeley.edu
AF: Department of Chemistry, University of California, Berkeley, CA 94720 United States
AU: Skelley, A M
P51D-0962 AF: Department of Chemistry, University of California, Berkeley, CA 94720 United States
AU: Scherer, J R
P51D-0962 AF: Department of Chemistry, University of California, Berkeley, CA 94720 United States
AU: Jayarajah, C
P51D-0962 AF: Department of Chemistry, University of California, Berkeley, CA 94720 United States
AU: Mathies, R A
P51D-0962 AF: Department of Chemistry, University of California, Berkeley, CA 94720 United States
AB: We have previously demonstrated the design, construction and testing of a portable microchip capillary electrophoresis (CE) instrument called the Mars Organic Analyzer (MOA) for analysis of amino acids and amine containing organic molecules (1). This instrument is designed to accept organic compounds isolated from samples by sublimation or by subcritical water extraction, to label the amine groups with fluorescamine, and to perform high resolution electrophoretic analysis. The CE instrument has shown remarkable robustness during successful field tests last year in the Panoche Valley, CA (1) and more recently in the Atacama Desert, Chile (2). For successful operation on Mars, however, it is necessary to operate autonomously and to analyze large numbers of samples, blanks, and standards. Toward this end we present here two advances in the MOA system that test key aspects of an eventual flight prototype. First, we have developed an automated microfluidic system and method for the autonomous loading, running and cleaning of the CE chip on the single channel MOA instrument. The integration of microfabricated PDMS valves and pumps with all-glass separation channels in a multilayer design enabled creation of structures for complex fluidic routing. Twenty sequential analyses of an amino acid standard were performed with an automated cleaning procedure between runs. In addition, dilutions were performed on-chip, and blanks were run to demonstrate the elimination of carry-over from run to run. These results demonstrate an important advance of the technology readiness level of the MOA. Second, we have designed, constructed and successfully tested a lab version of the multichannel instrument we initially proposed for the MSL opportunity. The portable Multi-Channel Mars Organic Analyzer (McMOA, 25 by 30 by 15 cm), was designed to sequentially interrogate eight radially oriented CE separation channels on a single wafer. Since each channel can be used to analyze 20 or more samples, we estimate that one microchip would be able to analyze hundreds of samples during a rover mission. The radial scanning optical system uses a stepper motor to servo the 400 nm diode laser excited confocal optical system to the desired electrophoresis channel and to collect and detect the fluorescence signal. Latching solenoids actuate a network of 32 microfabricated PDMS valves and pumps that control the microfluidic operations. A liquid cooling system maintains the entire chip at ~10 °C for optimal chiral separations. Electronic elements of the instrument are addressed by an integrated digital multiplexing chip so that the operation of the optical system, detection system, and electrophoretic voltages are controlled by a single data acquisition card. The limit of detection (LOD) of the McMOA instrument was found to be within 2x of the single channel instrument (LOD = 0.1 nM of T659, a fluorescent dye with similar fluorescent properties to fluorescamine). The sensitivity and performance of each channel was characterized by separating an amino acid standard; the peak heights and resolutions in the individual channels varied by less than 15%. Separations of biogenic amines in complex samples such as wine, sublimed bacteria, and a Miller-Urey experiment will be presented. Fluidic designs to enable the autonomous operation of the McMOA instrument and redundant microfluidic addressing of the various channels with bus structures are under development. 1. Skelley, A. M. et al. (2005) Proc. Natl. Acad. Sci. U.S.A. 102, 1041-1046. 2. Skelley, A. M. et al. (2005), AGU abstract submitted.
UR: http://www.astrobiology.berkeley.edu
DE: 6225 Mars
DE: 6297 Instruments and techniques
SC: Planetary Sciences [P]
MN: Fall Meeting 2005