Novel separation technology for high-speed gas chromatography: Theoretical and experimental approaches to separation optimization.

摘要

In order to attain a highly efficient high-speed gas chromatography (GC) separations, all experimental/instrumental parameters (i.e., capillary length and inner diameter; stationary phase composition and thickness; carrier gas velocity; oven temperature and temperature programming rate) need to be properly selected and optimized. The optimization of GC separations is vital to reduce the amount of time required for chromatographic analysis down to the time frame of a chemical sensor. This work has taken a dual approach to the optimization of high-speed GC separations through the use of both chromatographic theory and experimental modification/optimization. The novel GC theory developed within this work, as it applies to high-speed separations, can be applied as a means of separation and instrument evaluation. This novel theoretical framework is utilized to demonstrate the advantages, in terms of minimum plate height (Hmin), separation efficiency per unit time (Nopt/tM) and the peak width at the base of theoretical chromatographic peaks (wb opt) , of using short capillary columns with small inner diameters. The novel theoretical framework is revisited throughout this work as a means of evaluation of subsequent experimental optimizations. This work explores the theoretical optimization of the separation column dimensions and carrier gas velocity and the experimental optimization of the separation temperature and stationary phase composition and thickness. Resistive heating of the separation column results in a rapid temperature program capable of solving the general elution problem for high-speed separations, which optimizes the separation temperature. Optimizing the stationary phase composition, through the implementation of highly selective novel materials, is a means of separating a subset of compounds from a larger sample matrix. The combination of a novel stationary phase and resistive heating in the improved microfabricated GC (micro-GC) chip results in a chip capable of separating a mixture of compounds with low energy and carrier gas consumption.