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Graduation Term

Summer 2026

Degree Name

Master of Science (MS)

Department

Department of Chemistry

Committee Chair

Christopher Mulligan

Committee Member

Jeremy Driskell

Committee Member

Christopher Hamaker

Abstract

Rapid and reliable monitoring of environmental pollutants is essential for understanding contaminant behavior and mitigating ecological and human health risks. Conventional analytical techniques for environmental analysis often require extensive sample preparation and long analysis times, limiting their suitability for rapid screening applications. Here, we investigate the application of 3D-printed cone spray ionization-mass spectrometry (3D-PCSI-MS) as a rapid ambient ionization platform for direct analysis of environmental contaminants in soil. The first part of this work focuses on the validation of a previously-developed reactive 3D-PCSI-MS method for heavy metal detection in soil. The method utilizes a chelation-based ionization approach in which metal ions form ionizable complexes with ligands prior to mass spectrometric detection. The analytical performance of the technique was evaluated through comparison with energy-dispersive X-ray fluorescence spectroscopy (EDXRF), with particular emphasis on the determination and comparison of detection limits for Pb and other environmentally-relevant metals. The results demonstrated that 3D-PCSI-MS provides comparable or improved sensitivity for several metals while allowing direct analysis with minimal sample preparation. The second part of the study investigates the environmental transformation of N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD), a tire-derived antioxidant of emerging environmental concern. Using 3D-PCSI-MS, the oxidative dehydrogenation of 6PPD in soil was monitored in real time through the detection of diagnostic ions corresponding to the parent compound, intermediate species, and dehydrogenated product. Kinetic studies performed under dry, wet, acidic, and alkaline soil conditions demonstrated that soil chemistry strongly influences transformation behavior, with the fastest dehydrogenation observed under alkaline conditions and the slowest under acidic conditions. Overall, this work demonstrates the versatility of 3D-PCSI-MS for rapid environmental analysis and highlights its potential for direct monitoring of both inorganic and organic contaminants in complex soil matrices.

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