Turbine engine fuels are complex mixtures of hydrocarbons which have until recently, been obtained almost exclusively from petroleum. There is growing interest in developing alternative feedstocks for the eventual production of high-quality turbine engine fuels. The major analytical technique for separating the chemical constituents and analyzing fuels and synfuel feedstocks is high-resolution gas chromatography (HRGC), and the extreme chemical complexity of these hydrocarbon mixtures continues to challenge even the most sophisticated HRGC techniques. Therefore, the principal objective of this research was to identify and evaluate advanced HRGC instrumental procedures which show potential for improving the analysis of hydrocarbon jet fuels and various feedstocks. A gas chromatograph can be viewed as an assembly of individual components arranged to form a time invariant linear system. Accordingly, a systems approach has been used In this investigation to study, refine, and modify HRGC instrumentation. The chromatographic 11. AS APPLIED TO THE ANALYSIS OF HYDROCARBON FUELS AND OTHER COMPLEX ORGANIC MIXTURES, Volume I, Chromatographic System Details 19. analysis of a complex organic mixture requires a system capable of efficient, quantitative transport of solute molecules admitted to the system, and the injection of a complex broad-molecular-weight-range organic sample presents special problems to HRGCanalysis. An important topic relevant to complex, organic mixture analysis arid the generation of analytical data (qualitative and quantitative) is elutiori zone profile. The complete HRGC system must be capable of migrating, sensing, and eventually recording symmetrical zone profiles accurately. For maximum information content to be obtained ironian HRGC system, the output signal must be properly amplified and recorded. Also the many devices that handle and display the output chromatographic signal are especially important with respect to quality of the analytical information. In the future, aviation turbine fuels, along with geochemical and biomass feedstocks, will continue to be analyzed by HRGC, since research in this field and in this technique is quite active.