Development of gas chromatographic and mass spectrometric techniques for the analysis of Polycyclic Aromatic Compounds (PACs) in environmental samples
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Date
2020
Authors
IDOWU, IFEOLUWA GRACE
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Abstract
Concerns emanating from the presence of polycyclic aromatic compounds (PACs) in the environment especially as a yardstick for overall environmental health have been a challenge for several decades. Polycyclic aromatic compounds are a complex and structurally diverse class of compounds many of which can exist as isomers. Approaches to measure these compounds in environmental samples have relied on techniques based on gas chromatography coupled to mass spectrometry (GC/MS) at unit mass resolution. For example, the quantitation of the 16 US Environmental Protection Agency priority polycyclic aromatic hydrocarbons (PAHs) uses GC/MS and selected ion monitoring (SIM) of diagnostic m/z values of individual PAHs. Although this approach works well for the 16 priority PAHs, for more complex PACs, GC/MS in SIM mode is largely unreliable. Reasons for this include low selectivity of the SIM mode, insufficient chromatographic and mass resolution and the lack of commercially available authentic analytical standards. The overarching hypothesis of my thesis, therefore, is that more sophisticated chromatographic and MS techniques will provide more accurate measurements of PACs in the environment. The first advancement I made to the field of PAC research was the development of a one-dimensional GC coupled to MS method in the multiple reaction monitoring (MRM) to measure a suite of PACs. The method I developed was fully validated according to the EURACHEM guide - The Fitness for Purpose of Analytical methods and represents a significant improvement in the current SIM approach to quantitation of PACs in environmental samples. The second major advancement I made to the field of PAC research was the validation of a comprehensive 2D GC (GC×GC) high resolution time-of-flight (HR-TOF) MS method for the separation and quantitation of PACs. In this study I was able to exploit the increased peak capacity of the GC×GC system (relative to 1D) and the specificity of the HR-TOF/MS to quantify individual isomers of PAC compounds that were not attempted before. The methods I developed were paramount to the success of 2 other studies: (i) the GC/MS MRM method was used to understand the kinetics of PAH absorption to a highly sorptive medium that is used by industry to remediate the aquatic environment during/after an oil-spill and, (ii) the GC×GC-HR-TOF/MS was used in the detection of novel halogenated PACs in biological samples from the Alberta Oil Sands Region. The results of my work will have an impact and influence on future studies on source apportionment and chemical fingerprinting of crude-oil and will support much needed toxicological and monitoring studies of individual PAC isomers in the environment.
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Keywords
Polycyclic Aromatic Compounds, Soil, Crude Oil, Biota, Method development, Water, Gas chromatography, Sediment, Coal, Two-dimensional
Citation
Johnson, W., Idowu, I., Francisco, O., Marvin, C., Thomas, P. J., Stetefeld, J., & Tomy, G. T. (2018). Enumeration of the constitutional isomers of environmentally relevant substituted polycyclic aromatic compounds. Chemosphere, 202, 9-16.
Idowu, I., Francisco, O., Thomas, P. J., Johnson, W., Marvin, C., Stetefeld, J., & Tomy, G. T. (2018). Validation of a simultaneous method for determining polycyclic aromatic compounds and alkylated isomers in biota. Rapid Communications in Mass Spectrometry, 32(3), 277-287.
Francisco, O., Idowu, I., Friesen, K. L., McDougall, M., Choi, S. S., Bolluch, P., ... & Tomy, G. T. (2018). Absorption of polycyclic aromatic hydrocarbons by a highly absorptive polymeric medium. Chemosphere, 201, 441-447.
Idowu, I., Johnson, W., Francisco, O., Obal, T., Marvin, C., Thomas, P. J., ... & Tomy, G. T. (2018). Comprehensive two-dimensional gas chromatography high-resolution mass spectrometry for the analysis of substituted and unsubstituted polycyclic aromatic compounds in environmental samples. Journal of Chromatography A, 1579, 106-114.
Xia, Z., Idowu, I., Marvin, C., Thomas, P. J., Johnson, W., Francisco, O., ... & Tomy, G. T. (2019). Identification of halogenated polycyclic aromatic hydrocarbons in biological samples from Alberta Oil-Sands Region. Chemosphere, 215, 206-213.
Idowu, I., Francisco, O., Thomas, P. J., Johnson, W., Marvin, C., Stetefeld, J., & Tomy, G. T. (2018). Validation of a simultaneous method for determining polycyclic aromatic compounds and alkylated isomers in biota. Rapid Communications in Mass Spectrometry, 32(3), 277-287.
Francisco, O., Idowu, I., Friesen, K. L., McDougall, M., Choi, S. S., Bolluch, P., ... & Tomy, G. T. (2018). Absorption of polycyclic aromatic hydrocarbons by a highly absorptive polymeric medium. Chemosphere, 201, 441-447.
Idowu, I., Johnson, W., Francisco, O., Obal, T., Marvin, C., Thomas, P. J., ... & Tomy, G. T. (2018). Comprehensive two-dimensional gas chromatography high-resolution mass spectrometry for the analysis of substituted and unsubstituted polycyclic aromatic compounds in environmental samples. Journal of Chromatography A, 1579, 106-114.
Xia, Z., Idowu, I., Marvin, C., Thomas, P. J., Johnson, W., Francisco, O., ... & Tomy, G. T. (2019). Identification of halogenated polycyclic aromatic hydrocarbons in biological samples from Alberta Oil-Sands Region. Chemosphere, 215, 206-213.