Planar microfluidic devices and selective detection in gas chromatography : techniques and applications

摘要

This graduate research work addresses current techniques and method developments in gasudchromatography. The two major themes of the work are to enhance the chromatographicudperformance and reliability of contemporary capillary column chromatography with the use ofudplanar microfluidic devices, and to garner the power rendered by selective detectors such asudmicromachined differential ion mobility detection for the improvement of chromatographicudaspects related to the portability, selectivity, sensitivity, and throughput of analytical systems.udIncluded in this work are innovative analytical methods developed and successfully implementedudto address difficult, unmet, and unarticulated chromatographic needs that have been encounteredudby the community of practice, particularly in the petrochemical and chemical industries.udOver the course of the development of gas chromatography as a technique, many usefuludanalytical approaches were developed to take advantage of the availability of hundreds ofudpacking materials employed as stationary phases. However, the tools and devices designed forudthe use in column connectivity for the packed column era are not purposely meant forudcontemporary capillary column technology. Unfortunately, reliable options are few and farudbetween. Recent advances in metallurgy, metal injection molding, deactivation chemistry, laserudetching, and diffusion bonding techniques have resulted in the availability of planar microfluidicuddevices with features such as built-in fluidic gates, leak-free durability, improved inertness, inovenudand non-contact switching. Therefore, planar microfluidics becomes an important area ofudresearch in chromatography. In this work, the important tactical and strategic use of theudaforementioned devices in capillary gas chromatography was realized with multipleudchromatographic system configurations developed. The use of the device(s) for multi-dimensional gas chromatography, for hyphenated techniques, epitomized by a unified 1D/2Dudanalytical configuration and two-dimensional gas chromatography – mass spectrometry wereudattained.udWhen properly applied, selective detection can substantially ease the burden of separationudtraditionally imposed on the analytical column especially when the matrices of the samples areudincreasingly complex to tackle. Selective detection is an enabler to high-speed gasudchromatography which is a key component in the development of portable and hand-heldudanalytical devices. Therefore, research conducted in this field is not only important but criticaludto the capability of and sustainable development for gas chromatography as a technique. In theudcurrent research, the performance, benefit, and impact of using differential ion mobilityudspectrometry with resistively heated temperature programmable micromachined gasudchromatography is investigated and its usefulness highlighted. The synergy of hyphenatedudtechniques with other contemporary selective detectors such as the pulsed sulfurudchemiluminescence detector and mass spectrometry detector operating in selected ion monitoringudmode are also reaffirmed and illustrated in challenging industrial applications.