Multiple-stage microfabricated preconcentrator-focuser for micro gas chromatography system

The design, fabrication, and characterization of a multiple-stage Si microfabricated preconcentrator-focuser (/spl mu/PCF) for a micro gas chromatography (/spl mu/GC) system that can provide real-time quantification and identification of complex organic vapor mixtures are presented. The /spl mu/PCF consists of a Si microheater loaded with Carbopack B, Carbopack X, and Carboxen 1000 carbon adsorbent granules, and a Si micromachined cover plate. Deep reactive ion etching is utilized to produce mechanically robust fluidic interconnection adapters hermetically sealed to fused silica capillary tubing for connection to the other components in the /spl mu/GC. This three-stage device is designed to capture compounds spanning up to 4 orders of magnitude in volatility. The dead volume, thermal mass, heating efficiency, and pressure drop of the three-stage /spl mu/PCF are improved significantly over its single-stage /spl mu/PCF predecessor. We demonstrate the successful capture, desorption, and high-resolution chromatographic separation of a mixture of 30 common organic vapors using our three-stage /spl mu/PCF in a conventional GC system. The peak width at half height is <2.05 s for all compounds after elution from the GC column.