Biomimetic potentiometric sensor for chlorogenic acid based on electrosynthesized polypyrrole

A sensor was fabricated by modifying pencil graphite electrodes with molecularly imprinted polypyrrole (MIPpy) synthesized by electropolymerization of pyrrole monomer at constant potential in the presence of chlorogenic acid (CGA). A comparison between the non-imprinted modified pencil graphite electrode and the molecularly imprinted pencil graphite electrode is reported. Several important parameters controlling the performance of the polypyrrole and the method efficiencies were investigated and optimized. Surface morphology of imprinted and non-imprinted sensor was characterized by scanning electron microscope (SEM) and atomic force microscope (AFM). The molecularly imprinted layer exhibited selectivity and sensitivity toward CGA. Under optimized conditions, the calibration curve demonstrated linearity over a concentration range of 1 × 10−2 mol/L to 1 × 10−6 mol/L with a correlation coefficient (R2) of 0.993 and has life span of more than 3 months without any considerable change in the measured response. The sensor exhibited a sensitivity of −54.7 mV per decade. As an application, this potentiometric sensor has been successfully applied to the determination of CGA content in four different coffee samples and compared with HPLC results.