Direct determination of dibenzo[a,l]pyrene and its four dibenzopyrene isomers in water samples by solid-liquid extraction and laser-excited time-resolved Shpol'skii spectrometry.

Dibenzo[a,l]pyrene is considered the most potent carcinogen of all polycyclic aromatic hydrocarbons ever tested. Its four isomers, which include dibenzo[a,e]pyrene, dibenzo[a,h]pyrene, dibenzo[a,i]pyrene, and dibenzo[e,l]pyrene, are also carcinogenic and, therefore, a potential threat to humans. The method presented here provides a direct way for their determination in water samples. The entire procedure--from water extraction to LETRSS analysis--takes less than 15 min/sample and it consumes only 100 microL of organic solvent. This fact makes our approach environmentally friendly and cost-effective. Unambiguous isomer determination is accomplished via multidimensional data formats, namely, wavelength time matrixes, excitation-emission matrixes, and time-resolved excitation-emission matrixes. The analytical figures of merit demonstrate precise and accurate analysis at the sub-parts-per-billion level. Limits of detection are at the parts-per-trillion level. The potential of this approach for real-world analysis is illustrated with a heavily contaminated water samples.