Graphene-cobalt hexacyanoferrate modified sensor doped with molecularly imprinted polymer for selective potentiometric determination of bupropion

This study presents the first application of a graphene/cobalt hexacyanoferrate composite as an ion-to-electron transducer interlayer for the selective electrochemical determination of bupropion. The composite was prepared by homogeneously dispersing graphene with tween 80 and then decorating it with cobalt-hexacyanoferrate nanoparticles. Modifying glassy carbon electrodes with this interlayer improved and stabilized the measured potential by preventing the formation of an aqueous layer beneath the sensing membrane and enhancing charge transfer. The formation of the aqueous layer is a phenomenon commonly associated with solid-contact ion-selective electrodes. These electrodes encounter challenges regarding selectivity affecting their analytical performance in the presence of ions with similar charges and proper lipophilicity. Molecularly imprinted polymer (MIP) approach was employed to resolve the selectivity problem of analyzing bupropion in presence of naltrexone for obesity management. Scanning electron microscope and Fourier-transform infrared were utilized to characterize the fabricated composite and the MIP. Two cationic exchangers were separately integrated with the precipitated MIP to produce sensors for selective determination of bupropion in the dosage form and in spiked human plasma. The sensors exhibited Nernstian slope of 54.66 mV/decade and 55.89 mV/decade with detection limits as low as 2.51 × 10^{- 7} M and 2.0 × 10^{- 7} M. Moreover, three different metric ways verified sufficient sustainability of the proposed potentiometric method.