Elemental compositions of each of 100 to 500 different constituents (i.e., every peak in a mass-to-charge ratio range, 50 < m/z < 300) of lighter fluid, kerosene, turpatine, gasoline, diesel fuel, and two brands of mineral spirits (and their weathered analogs) made possible direct identification of each accelerant in a experimental fire, based on electron ionization 6.0 Tesla Fourier transform ion cyclotron resonance (EI FT-ICR) ultrahigh resolution mass spectrometry. Septum injection of as little as 500 nL of accelerant into an all-glass heated inlet system yielded definitive elemental compositions (molecular formulas) based on accurate mass measurement alone. Extraction and EI FT-ICR mass analysis of fire debris from a controlled burn of a couch with simple (lighter fluid) and complex (turpatine) ignitable liquid yielded dozens of elemental compositions that served as a unique "fingerprint" for each petroleum product, despite the presence of up to 249 additional extracted matrix and pyrolysis components. Forty-five of 56 lighter-fluid constituents and 126 of 133 turpatine constituents were identified in the debris from a fire staged for each respective accelerant. 9 figures, 1 table, and 51 references