Development and Evaluation of Situationally Specific Inlet Systems for Gas Chromatography and Multi-Dimensional Gas Chromatography.

Abstract

The gas chromatograph is the most commonly used instrumentation for the analysis of volatile and semi-volatile organic compounds (VOCs) worldwide. Recent estimates place the number of GCs currently in use at over 300,000 instruments. Analysis of ambient atmospheric vapor samples for VOC’s is relevant in industrial safety compliance monitoring, environmental quality monitoring and the diagnostic analysis of human breath. The usefulness of a multi-bed sorption trap using discrete beds of carbon-based sorbents and its use in inlet systems for gas chromatography and comprehensive two-dimensional gas chromatography is demonstrated in this work. The experimental studies presented in this work address different uses of the multi-bed sorption trap for various analyses. These include the analysis of volatile organics in air, the analysis of human breath, and a inlet system designed for pyrolysis-preconcentration with GCxGC. Comprehensive two-dimensional gas chromatography (GCxGC) is well suited to the analysis of complex samples and is used in the analysis of human breath in this work. Comprehensive two-dimensional separations are achieved by connecting in series two capillary columns using stationary phases of different selectivity by means of a concentration-modulator interface. The purpose of this work was to develop and evaluate inlets using the sorption-based, multi-bed preconcentrator to solve specific problems relating to the analysis of volatile and semi-volatile compounds. Results of the studies presented in this work demonstrate the development of a functional multi-bed sorption based preconcentrator able to collect and inject analytes over a wide range of functionalities and volatilities. Through the addition of a length of thick film capillary column in series with the multi-bed preconcentrator, the effective usable range of the preconcentrator was extended from C14 to at least C24. The final work demonstrated the effectiveness of the multi-bed sorption-based preconcentrator combined with comprehensive two-dimensional gas chromatography for the investigation of the components of human breath.