A flat, premixed, atmospheric, laminar, fuel-rich flame of ethane/oxygen/argon has been studied at an equivalence ratio (phi) of 2.6 by direct on-line gas chromatography/mass spectrometry (GC/MS) analysis. Samples were transported to the GC/MS through a heated quartz microprobe and analyzed without any pre-concentration methods. Mole fraction profiles for over 30 species were determined in the range of 0.45 to 1.0 x 10(-8). These species included a large number of aromatics, substituted aromatics and polycyclic aromatic hydrocarbons (PAH). The measurements provide information for the identities and levels of hazardous air pollutants formed in combustion systems and contribute new data to the development and validation of detailed reaction mechanisms. The largest PAHs detected and quantified, at peak concentrations of about 3 x 10(-6), were the C18H10 species (226 Daltons) cyclopenta(cd)pyrene and benzo(ghi)fluoranthene.