Capillary zone electrophoresis separation of azaarenes with sensitive UV absorption photometric detection after cationic solid phase extraction and field amplified sample stacking

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 °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.