"This report describes a preliminary application of supercritical fluid mass spectrometry (MS) techniques developed at Battelle-Northwest to the analysis of a middle distillate fuel, an emission particulate extract, and the emission particulates themselves. These techniques include capillary column supercritical fluid chromatography (SFC) (alone) and coupled with MS, direct fluid injection (DFD/MS, and supercritical fluid extraction (SFE)/MS. These techniques are still in an early stage of development, but have demonstrated considerable potential for difficult analytical problems. The present work demonstrates the feasibility of achieving high resolution separations of complex mixtures with SFC using nonpolar CO2 as the mobile phase. Additionally, these analyses have provided an evaluation of the limitations of the present detector interfaces, resulted in further design improvements, and emphasized research areas for further investigation. The present work also demonstrates that SFC/MS application to complex mixtures can provide good separations and usable mass spectra. DFI/MS using supercritical ammonia was used to provide an efficient method of transporting sample components to the ionization source to obtain accurate molecular weight distribution data and structural information for rapid analysis of materials for which suitable separations have not yet been developed. Finally, high molecular species up to mass 1400 amu were detected during SFE/MS of the emission particulates using supercritical ammonia. The necessary research required to elevate the various supercritical fluid methods to routine application is summarized."