Submission Date

4-26-2024

Document Type

Paper- Restricted to Campus Access

Department

Chemistry

Adviser

Eric Williamsen

Committee Member

Amanda J. Reig

Committee Member

Anthony Lobo

Department Chair

Amanda J. Reig

Project Description

Polymers are macromolecules composed of hydrogen, carbon, and other elements. Plastics, like polyethylene (PE) or polyethylene terephthalate (PET), are synthetic polymers that persist in the environment due to a lack of efficient and effective means of degradation. Studies have reported that microorganisms with cutinase domains show promise in degrading plastics, and thermophilic microbes contain these domains. Cutin serves as model system for PET in this study, and by burying it in thermophilic cultures containing compost, it is possible to observe its degradation process. Gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC) can separate, identify, and quantify the degradation products. This study presents a five-minute HPLC method for detecting and separating saturated fatty acids consisting of eight to 16 carbons and an 18-carbon unsaturated fatty acid in acetonitrile solution. A GC-MS method is presented for identifying and separating underivatized fatty acids from compost. Dissolving samples in cyclohexane and ramping the oven temperature from 45 to 325 °C were key components of the method. Furthermore, selective ion monitoring (SIM) mode studies greatly decreased the detection limits of the underivatized fatty acids. Quantitative studies using SIM mode were also attempted, but only concentrations of 1 mM and greater could be discerned from each other. Being able to detect these by-products is crucial in advancing the current knowledge of the cutin degradation process and its potential applications to PET degradation. Finally, this study presents a simple GC-MS scan and SIM mode method for identifying ethylene glycol at concentrations as low as 100 µg/mL in 50% aqueous acetonitrile solution, which will be necessary for quantifying PET degradation.

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