Monitoring oil spill contamination in seawater using molecularly imprinted polymer thin-films and direct solid-state fluorometric detection.

A molecularly imprinted polymer thin film (MIP) on a polyethylene terephthalate (PET) substrate for the selective extraction and solid-state fluorescence detection of dibenzothiophene (DBT) as a marker of oil spills in marine environments was developed. The MIP thin films were produced via UV-initiated polymerization of a polymeric mixture, giving a mechanically robust thin film without the necessity to modify the substrate surface. This solid-state fluorometric technique eliminated the need for extraction by providing a direct measurement of fluorescence from the solid phase, reducing sample pre-treatment requirements. Linear responses were observed over a concentration range of 5.0 to 80.0 µg L⁻1 (R2 = 0.9906). Furthermore, a detection limit of 1.74 µg L⁻1 (n = 15) was established. Acceptable selectivity towards DBT was shown by the MIP thin films in comparison to structurally similar aromatic compounds such as naphthalene and indole, which resulted in minimal interference with the signal. The reliability of the thin-film was further proven when the film was applied to untreated seawater samples, resulting in negligible matrix effects and quantitative results. In addition, the flexibility of the PET substrate will allow an easy adaptation to portable sensing units. This new MIP thin-film with rapid fluorescent detection offers a highly sensitive, selective and user-friendly tool for the early detection and assessment of oil spills in marine environments.