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Theoretical understanding and method development for high performance liquid chromatography-mass spectrometry for environmental analysis
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- Author / Creator
- Craven, Caley B
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Method development is a fundamental key step for effective and efficient analytical separations and analyses. Of particular importance is method development for high performance liquid chromatography-mass spectrometry (HPLC-MS). Specifically, environmental analysis applications require dedicated method development to help solve the complex questions associated with any environmental sample. To effectively make methods for environmental analysis, a firm understanding of HPLC and MS is needed. Chapter 1 includes a review on the theory of the instrumentation and methodology used in this thesis.
In Chapter 2, the selectivity and retention changes caused by mobile phase on four classes of hydrophilic interaction liquid chromatography (HILIC) columns were investigated. The effect of Na+Cl−, Na+ClO4−, Na+PF6−, and Na+CF3CO2− mobile-phase additives were explored for neutral, cationic, anionic, and zwitterionic analytes under HILIC conditions of 70–90% acetonitrile. These electrolytes altered the retention and selectivity on silica, zwitterionic and diol columns. Neutral analytes were unaffected. Cationic and anionic analytes increase and decrease in retention, respectively, by the following order of electrolytes: Na+PF6− ≈ Na+ClO4− > Na+CF3CO2− > Na+Cl−. Altering the buffer cation (Li+, Na+, K+) caused small but statistically significant changes in retention. The accumulation of chaotropic ions at the ACN/water interface disrupt both the water layer and other ionic interactions, causing the changes seen in retention and selectivity.
In Chapter 3, the effect of mobile phase preparation in HILIC were examined. Three different eluent preparation methods were examined. Due to the contraction of solvent upon mixing, different eluent preparation methods result in significant differences in the retention in HILIC. Additionally, differences in the buffer counterions used affected retention in HILIC, but to a less degree than the mobile phase preparation method.
In the latter half of the thesis, I moved from fundamental studies of HILIC to practical applications of HPLC-MS to show the importance of analytical method development for authentic environmental samples. Chapter 4 provides a critical review of literature on cannabis and its associated pesticides used to aid its growth. This reviewed the history of cannabis and its current prevalence. Additionally, Chapter 4 reviews the current analytical challenges and method development for the detection of pesticides in cannabis. This particularly focuses on current guidelines set by Health Canada to ensure the quality, safety, and efficacy of cannabis and cannabis products.
In Chapter 5, a high performance liquid chromatography mass spectrometry method was developed for the determination of pesticides in cannabis growing facilities. This method involved a simple wipe-sampling method with HPLC-MS/MS and was able to determine 82 of the 96 pesticides regulated by Health Canada. This method’s applicability was demonstrated in two separate cannabis growing facilities, a certified and non-certified site. A total of 41 pesticides were detected at the non-certified site while only 6 were observed at the certified site.
In Chapter 6, a preliminary study is provided to highlight current gaps in method development in environmental analyses. This study examines the use of HILIC-MS/MS with water analysis to show challenges in method development and application. Proposed future work revolves around minimizing or overcoming these challenges and gaps. This thesis highlights the importance of thorough and sensitive analytical methodologies to answer important environmental analysis questions. -
- Subjects / Keywords
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- Graduation date
- Fall 2021
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.