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This paper describes different approaches to achieve highperformance microfabricated silicon-glass separation columns for micro gas chromatographic (µGC) systems. The capillary width effect on the separation performance has been studied by characterization of 250 µm-, 125 µm-, and 50 µm-wide singlecapillary columns (SCCs) fabricated on a 10 × 8 mm 2 die. To address the low sample capacity of these narrow columns, the paper presents the first generation of MEMS-based "multicapillary" columns (MCCs) consisting of a bundle of narrow-width rectangular capillaries working in parallel. The theoretical model for the high-equivalent-to-a-theoretical-plate (HETP) of rectangular MCCs has been developed, which relates the HETP to the discrepancies of the widths and depths of the capillaries in the bundle. Two-, four-, and eight-capillary MCCs have been designed and fabricated to justify the separation ability of these columns. These MCCs capable of multi-component gas separation provide a sample capacity as large as 200 ng compared to 10 ng for 50 µm-wide single capillary columns.

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This paper reports on a method for self-patterned electroplating to selectively deposit gold on vertical surfaces of microfabricated silicon structures. This method was developed out of the effort to realize microfabricated multicapillary columns (µMCC) for chromatographic separation aimed for handheld chemical analysis. Results showed the successful selective vertical wall electroplating of µMCCs comprising an unprecedented number of channels (8 and 16). The µMCCs were functionalized using self-assembly of thiol groups and evaluated for their chromatographic performance. µMCCs demonstrated high separation efficiency as indicated by the 6500/m theoretical plate number and proved to have high sample capacities, which increases with the number of capillaries operating in parallel in these MEMS columns.

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This communication presents selective preconcentration of the anesthetic agent (Propofol) and the elimination of unwanted species from a representative sample of human breath. In this approach, a micro preconcentrator (microPC) consisting of embedded high-aspect-ratio pillars (30 microm x 120 microm chi 240 microm), an outer dimensions of 7 mm x 7 mm (encompass more than 3500 micro pillars), total inner surface area of approximately 10 m(2), and a total inner volume of approximately 6.5 microL was used to selectively preconcentrate Propofol. The microPC has on-chip thermal desorption capability and was coated by electrodeposited gold as an adsorbent material. Experimental evaluations showed successful preconcentration of trace level of Propofol from a mixture containing several volatile organic compounds diluted in water-like solvent (1-propanol) and the efficient removal of non-polar compounds present in the mixture.