Synovec, Robert RSAbdigali, Perizat2026-02-052026-02-052026-02-052025Abdigali_washington_0250O_28977.pdfhttps://hdl.handle.net/1773/55164Thesis (Master's)--University of Washington, 2025This thesis work highlights Solid Phase Extraction (SPE) coupled with Intuvo 9000 Gas Chromatography (GC), comprehensive two-dimensional (2D) gas chromatography-time-of-flight mass spectrometry (GC×GC-TOFMS), and one-dimensional gas chromatography-mass spectrometry (GC-qMS) to study the chemical components of a Test Mixture and contaminated by a diesel water sample. Diesel compounds were found during the first step of the analysis on one- dimensional GC-qMS. However, due to significant peak overlap, the compound resolution and identification were limited. GC×GC-TOFMS was used to analyze samples and its SPE extracts to overcome those limitations. During the analysis of the Test Mixture, a consistent temperature program and other conditions were adjusted on GC-qMS developed method. Nonadecane peak intensities were used as an example compound to find the limit of detection (LOD), which produces detection ability at low concentrations, and gave an instrumental practical value of 4 ppm. To analyze changes and determine which compounds were most reduced or eluted during the extraction, chemometric techniques such as Principal Analysis (PCA) and tile-based F statistic ratio (F-ratio) analysis were used. A significant change in analytes was shown by the separation of the extracts and original neat sample by PCA. To reduce noise and correct retention time shifts, the chromatograms with more than 2500 differential areas were reduced to around 1216 significant features using F-ratio analysis. A detailed analysis of a typical peak at mass-to-charge ratio 120 discovered that the Extracts had a weaker signal intensity than the Original Neat Diesel Sample, which shows partial compound loss after extraction. When comparing the real laboratory data with the NIST library mass spectrum, it has strong match across significant fragment ions, confirming the identification of 1-ethyl-2methylbenzene.application/pdfen-USnoneChemistryContaminated waterDiesel-contaminationEcologyone-dimensional gas chromatographytwo-dimensional gas chromatographyChemistryEnvironmental scienceChemistryThesis