Screening potential of solid-phase extraction and solid surface room temperature fluorimetry for polycyclic aromatic...

The analytical potential of solid-phase extraction and room temperature fluorimetry for screening polycylic aromatic hydrocarbons in water samples is evaluated. Solid-phase extraction was performed via a syringe procedure previously reported (Talanta 52 (2000) 727). The simplicity of fluorescence measurements on the solid substrate is equivalent to solution measurements. Since oxygen quenching of fluorescence is not significant, placing the extraction membrane in the substrate holder of the spectrometer rapidly performs fluorescence measurements. Limits of detection at the pg ml(-1) level were estimated for several pollutants. With a commercial spectrofluorimeter, benzo(a)pyrene was quantitatively determined at the 5 pg ml(-1) concentration level. This concentration compared favorably to limits of detection estimated by laser-induced fluorimetry. A unique advantage of this approach was the possibility of adjusting the volume of extracted water to reach concentration levels below instrumental detection levels. Since SPE procedure was rapid and simple the trade-off of including an additional experimental step to lower limits of detection was advantageous. Although the selectivity of this approach was not fully investigated, our studies showed that selective excitation was sufficient to identify benzo(a)pyrene in a seven-component mixture and spiked Red River water of unknown composition.