Clean-up and analysis of carbazole and acridine type polycyclic aromatic nitrogen heterocyclics in complex sample matrices

A HPLC method for the analysis of polycyclic aromatic nitrogen heterocyclics (PANHs) in complex sample matrices is presented. It isolated and separated carbazole and acridine type PANHs with an absolute recovery of between 79-98%. Open column chromatography is used as an initial step to isolate a PANH fraction. By applying normal-phase liquid chromatography using a dimethylaminopropyl silica stationary phase and utilising back-flush technique it was possible to separate the PANH fraction into two fractions containing acridine type and carbazole type PANHs, respectively. The method applied on a sample of solvent refined coal heavy distillate (SRC II HD). A number of 3-5 ring acridines and carbazoles were identified with GC-electron impact MS and quantified with GC-nitrogen-phosphorous detection. Polycyclic aromatic hydrocarbons (PAHs) were determined in the SRC II HD sample by automated on-line clean-up and analysis of the obtained PAH fraction with coupled LC-GC-flame ionization detection. There was no overlap between the PANH and the PAH fractions with this method, and carbazoles and acridines were efficiently separated. (C) 1997 Elsevier Science B.V.