Identification of salicylic acid using surface modified polyurethane film using an imprinted layer of polyaniline

The surface of polyurethane (PU) was modified by coating a thin layer of polyaniline (PAN) by oxidizing aniline using ammonium persulfate. Affinity sites for salicylic acid (SA) were created in the coated layer by non-covalent imprinting method. The imprinted layer adsorbed SA five times more compared to the nonimprinted surface reflecting the creation of affinity sites specific to SA on the surface. The equilibrium was attained relatively faster indicating that a material of this kind is suitable for sensing applications. The selectivity in recognizing the print molecule by the imprinted surface was assessed by comparing the extent of uptake of other structurally resembling molecules namely O-amino benzoic acid and acetyl salicylic acid. The selectivity factor was found to be 22 and 16.5. The adsorbed SA was detected using the technique of Fourier transform attenuated total internal reflection infrared spectroscopy (FT-ATR-IR). The results show that molecularly imprinted surface in combination with FT-IR is a useful approach for the sensing applications.