Fiber optic sensor for laser-induced room-temperature phosphorescence detection of polycyclic aromatic compounds

The development of a fiber optic sensor for the analysis of polycyclic aromatic compounds based on laser-induced room-termperature phosphorimetry is reported for the first time. A pulsed nitrogen laser was used to excite phosphorescence emission from compounds imbibed on filter-paper substrates. Thallium(I) acetate (0.1 M) was used to enhance phosphorescence emission from chrysene, 1,2-benzofluorene, 7,8-benzoquinoline, phenanthridine and 5,6-benzoquinoline. Lead(II) acetate (0.5 M) was employed for the determination of fluoranthene, which showed no phosphorescence signal on paper substrates pre-treated with thallium(I) acetate. Limits of detection at the ng/ml(-1) level were estimated for all the compounds. An improvement in the limits of detection of the nitrogen heterocyclic compounds was obtained by using a low-background paper substrate. Satisfactory reproducibility of measurements was observed, varying from 6.1% (chrysene) to 11.9% (7,8-benzoquinoline). The linear behavior of the sensor response was also evaluated. Linear dynamic ranges extend over two and three orders of magnitude and show the potential of the device for the quantitative analysis of environmental pollutants.