Gas chromatographic systems using nitrogen phosphorus and flame ionization detectors were utilized to analyze JP-5 fuels for reactants that lead to thermal instability products. High and low stability fuels defined by Naval Research Laboratory Gravimetric Jet Fuel Thermal Oxidation Test (GRAV JFTOT) were chosen to make gross and detailed comparisons of the reactants present in each fuel. Whole fuel samples were analyzed and compared. An acid extract, MeOH extract, and MeOH saturated with MDA extract were also analyzed for each fuel sample using GC analysis. This study demonstrates the usefulness of extraction of bases and polars in defining thermal instability reactants in jet fuels. Data indicates the MDA does not appear to be useful as an extraction modifier for polars.