Novel Strategies for Organosulfur Analysis in Gas Chromatography with Flame Photometric Detection
Date
2020-04-09
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Abstract
This thesis describes the development of novel methods to analyze organosulfur compounds using gas chromatography (GC) with flame photometric detection (FPD). The first area of exploration utilizes a water stationary phase for sulfur separations. Several organosulfur compounds are retained to varying degrees on this phase, while non-polar hydrocarbons are unretained. This prevents the co-elution of sulfur analytes with hydrocarbons and the response quenching that is often observed in GC-FPD. Overall, the water stationary phase is shown to be a useful alternative for the analysis of organosulfur compounds in complex matrices. Next, a sample preparation method using lead oxide particles or plumbite solution is demonstrated to complex thiols into a solid lead thiolate moiety that can be physically separated from complex sample matrices and then reconstituted as the original thiol in a simple replacement solvent for analysis. The method allows thiols to be selectively isolated from co-eluting peaks, which can simplify their determination and greatly reduce interference from signal quenching when using an FPD. As an extension of this technique, a selective chromatographic system is also demonstrated. This uses PbO or plumbite as a pre-column trap for thiols, which allows non-thiols to separate as normal while thiols are not eluted until in situ reconstitution. This illustrates the potential for their controlled GC analysis. Accordingly, results indicate that these methods could be useful alternative approaches for the selective analysis of such thiol-containing samples. Lastly, a novel miniaturized GC-FPD device built within a titanium platform (Ti µGC-FPD) is presented. The monolithic Ti device contains both a separation column and a shielded cavity to house the detector flame. The FPD employs a micro counter-current flame that is stabilized by opposing relatively low flows of oxygen and hydrogen, with minimum detectable limits of about 70 pg S/s for sulfur and 8 pg P/s for phosphorous. Overall, good separations with stable and sensitive detector performance are obtained with the device, and its sturdy Ti structure supports robust operation. Results indicate that this Ti µGC-FPD device may be a useful alternative approach for incorporating selective FPD sensing in µGC analyses.
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Keywords
gas chromatography, flame photometric detection, thiols, quenching, sulfur, stationary phase, water, miniature, titanium
Citation
McKelvie, K. H. (2020). Novel Strategies for Organosulfur Analysis in Gas Chromatography with Flame Photometric Detection (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.