Keywords

high temperature, microchip, gas chromatography, semi-volatile compounds, thermal gradient

Abstract

Miniaturization of gas chromatography (GC) instrumentation is of interest because it addresses current and future issues relating to compactness, portability and field application. While incremental advancements continue to be reported in microchip GC, the current performance is far from acceptable. This lower performance compared to conventional GC is due to factors such as pooling of the stationary phase in corners of non-cylindrical channels, adsorption of sensitive compounds on incompletely deactivated surfaces, shorter column lengths and less than optimum interfacing to injector and detector. In this work, a microchip GC system was developed that solves the latter challenge, i.e. microchip interfacing to injector and detector. A microchip compression clamp was constructed that seals injector and detector fused silica interface tubing to inlet and outlet ports of the microchip channels with minimum extra-column dead volume, and that allows routine operation at least up to 300 ºC. The compression clamp was constructed of a low expansion allow, KovarTM, to minimize leaking due to thermal expansion mismatch at the interface during repeated thermal cycling. A 5.0 m channel with a cross-section that approximately matches a 100 µm i.d. cylindrical fused silica column was fabricated in a silicon wafer using wafer vonding and deep reactive ion etching (DRIE) and coated statically with 1% vinyl, 5% phenyl, 94% methylpolysiloxane stationary phase. High temperature separations of C10-C40 n-alkanes and a commercial diesel sample were demonstrated using the system under both temperature programmed GC (TPGC) and thermal gradient GC (TGGC) conditions. TGGC analysis of a complex essential oil sample was also demonstrated.

Original Publication Citation

Ghosh, A., Johnson, J. E., Nuss, J. G., Stark, B. A., Hawkins, A. R., Tolley, L. T., Iverson, B. D., Tolley, H. D., and Lee, M. L. (2017). Extending the upper temperature range of gas chromatography with all-silicon microchip colwnns using a heater/clamp assembly. Journal of Chromatography A, 151 7, 134-141.

Document Type

Peer-Reviewed Article

Publication Date

2017

Publisher

Elsevier

Language

English

College

Ira A. Fulton College of Engineering and Technology

Department

Mechanical Engineering

Available for download on Saturday, September 29, 2018

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