Catalytic action of copper (II) ion on electrochemical oxidation of metformine and voltammetric determination of metformine in pharmaceuticals

The catalytic effect of Cu(II) ion toward the oxidation of metformine (MET) have been observed in NH3·H2O-NH4Cl buffer (pH 8.9; 0.1 M). The oxidation peak current of imino-group in guanidino-group of MET at 0.95 V at carbon paste electrode (C/PE) in the presence of 2.0 × 10−4 M Cu(II) ion was increased by about 20 times and the peak potential was unchanged compared with that in the absence of Cu(II) ion. Moreover, the oxidation peak current of MET at multiwalled carbon nanotube paste electrode (MWCNT/PE) was further increased by about three times compared with that at C/PE in the same medium. Based on the catalytic oxidation peak of MET by Cu(II) ion at MWCNT/PE, a voltammetric method for the determination of MET is developed. The peak current of the catalytic oxidation peak was proportional to MET concentration in the range of 2.0 × 10−7 to 1.0 × 10−5 M. The detection limit was 6.7 × 10−8 M.