Development of a new chemically modified carbon paste electrode based on nano-sized molecular imprinted polymer for selective and sensitive determination of naproxen

In this work, a new modified carbon paste electrode (CPE) was constructed for potentiometric determination of naproxen (NAP) based on its imprinted polymer as a chemical modifier. An efficient precipitation polymerization method was applied for the synthesis of nano-sized NAP molecular imprinted polymer (MIP). In the preparation of MIP, methacrylic acid and ethylene glycol dimethacrylate were used as the functional monomer and cross-linking agent, respectively. The nano-sized NAP-MIP was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). SEM images confirmed the nanostructure morphology of the prepared MIP, with a particle size range of 50-80 nm. The MIP based sensor with the optimum composition exhibits a good linear response with a slope of -59.5 +/- 1.5 mV per decade over the concentration range of 1.0 x 10(-9.5)-1.0 x 10(-1) mol L-1. It has a very low limit of detection, 3.0 x 10(-10) mol L-1, with a response time of 3 s. The potentiometric response of the sensor was independent of the pH of test solution in a wide range of 5.0-11.0. The proposed electrode shows a very good selectivity for NAP over other drugs. The chemically modified CPE indicated an excellent applicability for the determination of NAP in NAP capsules.