Parathion sensor based on molecularly imprinted sol-gel films

Thin films of a molecularly imprinted sol-gel polymer with specific binding sites for parathion were developed. The films were cast on glass substrates and on glassy carbon electrodes and were used to detect parathion in aqueous solutions. Gas-phase binding measurements were performed on coated quartz crystal microbalance resonators. The binding of parathion to the imprinted films in the liquid phase was investigated by steady-state experiments with analysis by GC-FPD and cyclic voltammetry. The imprinted films showed high selectivity toward parathion in comparison to similar organophosphates. The binding was shown to be very sensitive to the type of functional monomer used for imprinting, and that rational design of the matrix components is an essential step in molecular imprinting. Specific binding in the gas phase proved to be less sensitive to the imprinting effect and exhibits relatively high nonspecific binding. The difference between molecular recognition in the gas- and liquid-phase imprinted polymer is discussed.