Date of Award

7-17-2023

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Department of Chemistry

First Advisor

Christopher C.C.M Mulligan

Abstract

Long-term monitoring (LTM) of environmental matrices can assist in detecting the onset or changes in chemical contaminant plumes and evaluating subsequent remediation efforts, but bears extreme cost, with significant funds going towards shipping costs of field-collected samples for off-site processing via hyphenated MS methods. To this end, portable technologies that offer both direct sampling capability and high throughput operation are appealing. We report and characterize the use of filter cone spray ionization-mass spectrometry (FCSI-MS) towards the temporal and spatial profiling of pollutants from unprepared soil sample and demonstrate its utility on portable and commercial MS systems alike. MS systems employed for this work included a lab-scale ion trap MS (Thermo LCQ Fleet) coupled with a home-built FCSI ionization source. FCSI-MS allows direct profiling of analyte residues from complex matrices by employing on-board filtration and ESI-like ionization mechanism. Soil standards of varying compositions were spiked with target analytes and exposed to variable, yet controlled environmental conditions (such as moisture, temperature, etc.). Sub-samples of soil samples were then analyzed directly via FCSI-MS, utilizing common spray solvent systems and high voltage (4.5 kV) delivered via a clamping electrode. FCSI-MS operates akin to a 3D paper spray ionization (PSI) source, where a conical structure can house larger volumes of solid samples for extraction and ionization via ESI-like mechanisms. FCSI specifically employs on-board filtration via basic Whatman filter papers, retaining problematic materials that can cause instrumental hygiene issues and potential issues to MS vacuum systems. In this way, rapid, in-situ analysis of soil, a heterogeneous, solid-phase matrix containing fine particulate, was coupled to both lab-scale and portable MS instrumentation with high robustness. Systematic experiments were performed on well-known (e.g., amitraz) and emerging (e.g., sulfoxaflor) agricultural chemicals and other priority pollutants to monitor the persistence and fate in varying soil types. By varying soil type, residence time in soil, water content, light exposure, and pH, degradation kinetics were accurately assessed, deducing the role of known breakdown processes like hydrolysis, photolysis, etc. Depth profiling was also shown via core sampling, providing insight into pollutant runoff and potential entry into water tables. To show overall performance, metrics such as detection limit, ionization efficiency, etc. were collected, as well as the propensity of pollutant transformation and/or metabolic breakdown when exposed to environmental conditions.

Comments

Imported from Addo_ilstu_0092N_12478.pdf

DOI

https://doi.org/10.30707/ETD2023.20231004061827308432.999998

Page Count

77

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Available for download on Monday, September 22, 2025

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