In this work electrochemical behavior of papaverine as an antispasmodic was investigated on modified carbon paste electrode by using cyclic voltammetry, differential pulse voltammetry, electrochemical impedance spectroscopy and double step chronoamperometry techniques. Multiwall carbon nanotube and layered double hydroxide immobilized on carbon paste electrode. Results show that CNT/LDH/CPE enhances anodic peak current of papaverine compared with CNT/CPE and LDH/CPE. The nyquist plots reveal the least charge transfer resistant for the modified electrode, which the result confirms catalytic effect of modifier. The surface morphology of the electrode was studied by FE-SEM images. The effect of experimental parameters such as pH and scan rate on voltammetric response of papaverine was investigated. Maximum current was observed in phosphate buffer pH= 9.0. The electrode reaction followed a diffusion-controlled pathway. Wide dynamic range (0.10-100µM) with detection limit 0.04 µM was obtained for papaverine under optimized conditions. The relative standard deviation for 5 repeated measurement of 25µM papa was obtained 3.9%. The kinetics parameters such as electron transfer coefficient, ?=0.61, diffusion coefficient, D= 3.9×10 -4 cm 2 s -1 and catalytic reaction rate constant, K h =3.8×10 2 M -1 s -1 were also determined using electrochemical approaches. Low cost, easy preparation, high sensitivity and good selectivity have made the modified electrode suitable for determination of papaverine in real samples.
