Capillary zone electrophoresis (CZE) was used to enable selective and sensitive determination of five basic azaarenes (7,8-benzoquinoline, 7,9-dimethylbenz[c] acridine, 9-methylacridine, acridine, and dibenz[a, j] acridine) in diesel fuel using 9-amino-1,2,3,4-tetrahydroacridine as internal standard. Solid phase extraction was performed in a single step allowing sample clean-up. Field-amplified sample stacking was achieved using a more conductive background electrolyte (50 mmol L-1 phosphate buffer adjusted to pH 2.65 with 25% of acetonitrile) and a less conductive sample solution prepared in 1 mmol L-1 phosphoric acid with 20% acetonitrile. Instrumental conditions were: 25 kV at 15 degrees C and hydrodynamic injection (50 mbar) for 100 s. The LOD values in diesel (based on the signal-to-noise ratio 3: 1) were in the mg L-1 level. The method was able to detect some of the azaarenes in real samples. (c) 2014 Elsevier Ltd. All rights reserved.