DETERMINATION OF POLYCYCLIC AROMATIC-HYDROCARBONS IN SOIL SAMPLES BY MICELLAR ELECTROKINETIC CAPILLARY CHROMATOGRAPHY WITH PHOTODIODE-ARRAYDETECTION

The reliable quantification even of trace amounts of polycyclic aromat ic hydrocarbons (PAHs) is of great concern in environmental and also i n medical analysis. PAHs are typically small, uncharged, hydrophobic m olecules which do not dissolve well in water. Several methods were inv estigated and compared for the determination of such substances by cap illary electrophoresis, including systems where the analytes are provi ded with a charge (tetraalkylammonium ions) via solvophobic interactio n and systems based on micellar electrokinetic capillary electrophores is (MECC) using sodium dodecyl sulphate (SDS) and cetyltrimethylammoni um bromide as micelle-forming agents. Diode-array detection permitted the positive identification of the separated pure substances via their prerecorded UV-Vis spectra. By using an aqueous-organic electrophores is buffer [8.5 mM berate, 85 mM SDS, 50% (v/v) acetonitrile, pH 9.9], a mixture of seven standard PAHs could be separated and quantified wit hin 10 min. The detection limit was 10 pg. The calibration graph was l inear over five orders of magnitude. Compared with the chromatographic analysis used so far, the MECC method is faster, has a higher mass se nsitivity and requires a smaller sample volume. The method was used to quantify the PAH content of soil samples (heath sand) deliberately co ntaminated with a mixture of standard PAHs and with machine oil. Two P AHs (anthracene and chrysene) could be determined in samples collected during a biological soil decontamination process.