A novel application of nylon membranes to the luminescent determination of benzo[a]pyrene at ultra trace levels in water samples

Very simple and highly sensitive methods are presented for the determination of benzoa]pyrene, one of the most carcinogenic polycyclic aromatic hydrocarbons (PAHs). The approaches are based on solid-phase extraction of the analyte on a nylon membrane via a syringe procedure, and its fluorescent or phosphorescent determination on the solid surface. While the native fluorescence of benzoa]pyrene retained on a nylon surface is measured directly, room-temperature phosphorescence is induced by spotting a few microlitres of thallium(I) nitrate solution on the surface (heavy-atom effect). An enhancement of the phosphorescence signal was corroborated when the measurements were carried under a nitrogen atmosphere. The analytical figures of merit obtained under the best experimental conditions demonstrate the capability of detecting benzoa]pyrene at a sub-parts-per-trillion (sub-ng L⁻¹) level. The potential interference from other common PAHs and also from different metal ions was studied. The feasibility of determining benzoa]pyrene in real samples was successfully evaluated through the analysis of spiked tap, underground and mineral water samples of different origins. Recoveries obtained from spiked river waters were successfully compared with those provided by a reference method, through rigorous statistical analysis.