<p dir="ltr">Phosphatidylethanol (PEth) species are emerging as promising biomarkers for alcohol consumption due to their specificity and stability in biological samples. This thesis employs a quadrupole ion trap mass spectrometer to comprehensively profile 25 PEth analogs in dried blood spot (DBS) samples. The study adopts a semi-quantitative approach utilizing tandem mass spectrometry (MS/MS) to assess relative PEth analog abundances based on ion intensities without inducing fragmentation except that declustering is achieved. This method provides rapid data acquisition compared to absolute concentration determinations, with the potential to provide additional insights into individual metabolic and/or alcohol consumption patterns.</p><p dir="ltr">Initial analysis focuses on precursor ion intensities at unit mass resolution, revealing distinctive distribution patterns of PEth analogs across eight patient samples. Utilizing a heatmap generated from PEth analysis, significant patterns and similarities were identified among certain patient groups. Patient 2 and Patient 8 exhibit similar PEth profiles, while Patient 3, Patient 4, and Patient 5 form another group with comparable PEth analog intensities. Similarly, Patient 6 and Patient 7 also show analogous profiles, whereas Patient 1 stands out with a distinctly unique PEth profile. These observed groupings indicate that, despite the variability in individual responses to alcohol consumption, there are commonalities that can be leveraged to form supergroups based on PEth analysis.</p><p dir="ltr">Subsequent MS/MS analysis elucidates the structural diversity of the top five most abundant PEth analogs (<i>m/z </i>723.5, 751.5, 753.5, 773.5, and 775.5) by fragmenting isolated ions and recording product ion spectra. This approach facilitates the identification of multiple isomeric PEth molecules at specific precursor <i>m/z</i> values, enhancing the characterization of PEth species.</p><p dir="ltr">Principal Component Analysis (PCA) and Linear Discriminant Analysis (LDA) are employed to interpret MS/MS data, revealing distinct clustering patterns among patient samples based on their PEth profiles. These analyses highlight the discriminatory potential of PEth analogs in delineating alcohol consumption behaviors within a limited cohort.</p><p dir="ltr">Despite limitations related to sample size and cohort specificity, this study underscores the utility of LTQ mass spectrometry in rapid and comprehensive PEth analog profiling. The findings contribute to validating PEth species as reliable biomarkers for alcohol consumption, with implications for clinical diagnostics and forensic applications.</p>