RESUMEN
The catalytic effect of Cu(II) ion toward the oxidation of metformine (MET) have been observed in NH(3).H(2)O-NH(4)Cl buffer (pH 8.9; 0.1M). 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 x 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 x 10(-7) to 1.0 x 10(-5)M. The detection limit was 6.7 x 10(-8)M.
Asunto(s)
Cobre/química , Hipoglucemiantes/química , Metformina/química , Preparaciones Farmacéuticas/química , Tampones (Química) , Calibración , Carbono/química , Catálisis , Cationes Bivalentes/química , Electroquímica/métodos , Electrodos , Concentración de Iones de Hidrógeno , Nanotubos de Carbono/química , Oxidación-Reducción , Polvos/química , Espectrofotometría Ultravioleta , Comprimidos/química , TemperaturaRESUMEN
Molecular wires containing copper(II) (CuMW), in the form of the coordination polymer (Cu(II)4(bpp)4(maa)8(H2O)2).2H2O (bpp=1,3-bis(4-pyridyl)propane, maa=2-methylacrylic acid), and multiwalled carbon nanotubes (CNT) have been combined to prepare a paste electrode (CuMW/CNT/PE). The voltammetric response of the CuMW/CNT/PE to metformin (MET) was significantly greater than that of electrodes prepared from other materials, because of both the surface effect of CuMW and CNT and coordination of MET with the Cu(II) ion in the CuMW. A novel voltammetric method for determination of MET is proposed. In pH 7.2 Britton-Robinson buffer, using single sweep voltammetry, the second-order derivative peak current for oxidation of MET at 0.97 V (relative to SCE) increased linearly with MET concentration in the range 9.0 x 10(-7)-5.0 x 10(-5) mol L(-1) and the detection limit was 6.5 x 10(-7) mol L(-1).