Double molecular imprinting--a new sensor concept for improving selectivity in the detection of polycyclic aromatic...

Highly selective and robust polymer coatings for the detection of polycyclic aromatic hydrocarbons (PAHs) in liquid media have been generated by use of an innovative method of molecular imprinting. By imprinting with two different templates, the selectivity of the polyurethanes used was increased by creating diffusion pathways and molecular cavities. Analyte inclusion was detected both by fluorescence and by use of mass-sensitive transducers. It is possible to optimize layers in respect of the extraction of two different analytes or to achieve extremely high selectivity for a distinct analyte. In this way coatings can be tuned to the lean chrysene, e.g., and it is enriched by a factor of approximately fifty compared with the more quadratic pyrene with the same number of aromatic rings. Measurements of PAHs in water were also performed with a quartz crystal microbalance, which shows that humic acids are not incorporated by the layers and thus do not influence the fluorescence properties of the layers.