Molecularly imprinted sensor based on o-aminophenol for the selective determination of norepinephrine in pharmaceutical and biological samples

An electrochemical sensor has been developed for the selective determination of norepinephrine (NE) using the molecularly imprinted technique. The imprinted polymer film at the surface of glassy carbon electrode is prepared by the electropolymerization of o-aminophenol in the presence of NE. Imprinted polymer film was characterized by atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The imprinted sensor showed a well-defined anodic peak at a potential of ∼ 198 mV in phosphate buffer of pH 7.2 using square wave voltammetry. A linear increase in peak current was found with the increasing concentration of NE in the range from 50×10^-9 to 10×10^-6 mol L^-1and the limit of detection (3σ/b) was found to be 4.9×10^-10 mol L^-1. The imprinted sensor has been successfully employed to ascertain the content of NE in the commercially available pharmaceutical preparations. The biological applicability of the developed sensor has been delineated by the determination of NE in human plasma and urine samples using the standard addition method. The proposed sensor exhibited high degree of selectivity for NE in comparison to other structurally similar biomolecules present in biological samples, along with long term stability, good reproducibility and excellent capacity of regeneration of molecular recognition sites.