In the first case, samples of charred brown paper and cardboard from a warehouse fire were examined. With conventional gas chromatography flame ionization detection (GC/FID), the analysis reported gasoline present. However, further GC/mass spectrometry (MS) analysis that utilized aromatic ion profiling and peak identification indicated the presence of a mixture of gasoline and an Isopar product in the sample. Analysis with GC/FID in the second case of the burned wood sample would have yielded inconclusive findings. Again, aromatic ion profiling with subtraction of interference from terpene compounds indicated the presence of gasoline. In the third case, analysis by GC/MS of burnt debris from a desk drawer demonstrated that the peaks appearing in the chromatogram were due to pyrolysis and that no indication of an accelerant was found. These cases illustrate conclusive determinations in some situations where GC-FID is insufficient. 11 figures and 3 references (Author abstract modified)