An automatic method for the determination of carcinogenic 1-nitropyrene in extracts from automobile exhaust particulate matter has been developed. Organic matter was extracted from particulate matter and the extract was concentrated. Then the extract was injected into a two-dimensional (2D) high-performance liquid chromatograph (HPLC) with a fluorescence detection system. To improve the sensitivity a large sample volume (300 µl) was applied to the HPLC system using the double on-column focusing technique. To achieve full automation and high selectivity a reduction column packed with platinum black was introduced after the 2D HPLC system using a C₁₈ column as the primary column and a pentabromobenzyl column as the secondary column. This HPLC system could determine 0.01–3,000 ng ml⁻¹ of 1-nitropyrene in an extract from diesel and gasoline exhaust particulate matter at 40 min intervals.