Capillary Electrochromatography: Polycyclic Aromatic Hydrocarbons

Electrochromatography is utilized to separate a mixture of 16 different polycyclic aromatic hydrocarbons (PAHs). Fused-silica capillary columns ranging in size from 50 to 150 pm i.d. were packed (20-40-cm sections) with 3-pm octadecylsilica particles. A potential of 15-30 kV is applied across the 30-50-cm total length capillary column to generate electroosmotic flow that carries the PAHs through the stationary phase. An intracavity-doubled argon ion laser operating at 257 nm is used to detect the PAHs by laser-induced fluorescence. Efficiencies up to 400 000 theoretical platedm are obtained when detection is performed within the column packing and up to 150000 theoretical plates/m when detection is performed following a frit (used to hold the packing). The reproducibility of the peak retention times is better than 2% (RSD). The limits of detection for individual PAHs range between lo-'' and mol (10-9-10-11 M), with a linear response spanning 4 orders of magnitude in concentration.