A novel screen-printed potentiometric electrode with carbon nanotubes/polyaniline transducer and molecularly imprinted polymer for the determination of nalbuphine in pharmaceuticals and biological fluids

A novel screen-printed electrode (SPE) for potentiometric determination of nalbuphine (NAL) is described. Carboxylated multi-walled carbon nano tubes/polyaniline (f-MWCNTs/PANI) nanocomposite is used as an ion- to-electron transducer and is covered by a selective polyvinyl chloride (PVC) membrane incorporated with molecularly imprinted drug polymer (MIP) beads as a recognition receptor for potentiometric determination a synthetic narcotic, nalbuphine (NAL). The SPE displays a Nernstian response with a slope of 60.3 +/- 1.2 mV/ decade (R-2 = 0.999) over the concentration range 2.4 x 10(-7) - 5.0 x 10(-2) mol/L and a detection limit of 1.1 x 10(-7 )mol/L (0.04 mu g/mL) with response time less than 20 s (< 20 s). The interfacial capacitance of the proposed SPE is measured using chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS). The use of the f-MWCNTs/PANI nanocomposite layer improved the interfacial capacitance reached 52.5 mu F. Besides, it eliminated the formation of the undesired thin water-layer between the sensing membrane and the conducting substrate. This prevents membrane delamination and increases potential stability. The obtained high selectivity, sensitivity and potential stability offered a great applicability of the proposed SPE for the determination of nalbuphine in hospitals for rapid diagnosis of overdose patients and for quality control/quality assurance in pharmaceutical industry.