Silicon microfabricated column with microfabricated differential mobility spectrometer for GC analysis of volatile organic compounds.
Lambertus-GR; Fix-CS; Reidy-SM; Miller-RA; Wheeler-D; Nazarov-E; Sacks-R
Anal Chem 2005 Dec; 77(23):7563-7571
A 3.0-m-long, 150-microm-wide, 240-microm-deep channel etched in a 3.2-cm-square silicon chip, covered with a Pyrex wafer, and coated with a dimethyl polysiloxane stationary phase is used for the GC separation of volatile organic compounds. The column, which generates approximately 5500 theoretical plates, is temperature-programmed in a conventional convection oven. The column is connected through a heated transfer line to a microfabricated differential mobility spectrometer. The spectrometer incorporates a 63Ni source for atmospheric-pressure chemical ionization of the analytes. Nitrogen or air transport gas (flow 300 cm(3)/min) drives the analyte ions through the cell. The spectrometer operates with an asymmetric radio frequency (RF) electric field between a pair of electrodes in the detector cell. During each radio frequency cycle, the ion mobility alternates between a high-field and a low-field value (differential mobility). Ions oscillate between the electrodes, and only ions with an appropriate differential mobility reach a pair of biased collectors at the downstream end of the cell. A compensation voltage applied to one of the RF electrodes is scanned to allow ions with different differential mobilities to pass through the cell without being annihilated at the RF electrodes. A unique feature of the device is that both positive and negative ions are detected from a single experiment. The combined microfabricated column and detector is evaluated for the analysis of volatile organic compounds with a variety of functionalities.
Organic-compounds; Exposure-levels; Exposure-assessment; Air-quality; Air-quality-control; Air-quality-monitoring; Organic-vapors; Gas-chromatography; Gas-sampling; Gases; Electrochemical-analysis; Electrochemical-properties; Electrochemical-reactions; Electrochemistry; Electrophysiological-measurements; Ion-transport; Temperature-control; Atmospheric-pressure; Atmosphere-analyzers; Chemical-reactions
Department of Chemistry, University of Michigan, Ann Arbor, MI 48109
University of Michigan, Ann Arbor