Technological developments have enabled mass spectrometry (MS) to evolve asone of the most versatile, sensitive and widely used analytical methods. Key areas ofresearch in biological MS include the development of analyte-selective MSmethodologies, along with the design of MS compatible separation technology. Analytesof interest range from small, biologically active molecules in disease progressionresearch, to macromolecules such as proteins, in proteomics investigations. Advances inthese areas are vital to maintaining the level of sophistication that has become thebenchmark for MS analyses.Mass spectrometry has found a permanent station in disease progression studies,particularly in biomarker discovery. This is especially true for Alzheimer's disease (AD),a condition marked by widespread lipid peroxidation (LPO) in the brain. The mainhypothesis of the first part of this dissertation is that LPO produces aldehydes that canpotentially be exploited as AD biomarkers. Design of novel LC-MS/MS methods forbrain aldehyde analysis is described. The methods were applied towards aldehydequantification in the hippocampus, superior and middle temporal gyrus and cerebellum ofsubjects with early AD (EAD), mild cognitive impairment (MCI) and age-matchedcontrols. Results obtained indicated elevation of neurotoxic aldehydes in MCI and EADbrain and suggested that LPO occurred early in AD. Understanding AD progression hasbecome important for developing diagnostic methods and treatments.Mass spectrometry is also the major analytical tool in proteomics, where gelelectrophoresis is dominant in pre-MS separations. The main hypothesis of the latter partof this dissertation is that exposure of microbe fermenters including Clostridiumthermocellum to an external stimulus, such as ethanol, can alter the membrane proteome.Design of novel doubled-SDS-PAGE (dSDS-PAGE) methods for membrane proteinanalysis is described, as these proteins are under-represented in standard 2D-PAGE. Thenewly developed Bicine-dSDS-PAGE offered superior separation over other methods andwas applied towards analysis of wild type and ethanol-adapted C. thermocellum cellmembranes. Significant differences in protein expression were observed. Anunderstanding of ethanol adaptation will promote the design of more ethanol-tolerantstrains. Such an outcome can have dramatic effects in the fuel industry as the trendtowards more efficient fuel development gathers momentum.