Simultaneous determination of ascorbic acid, dopamine, uric acid and hydrogen peroxide based on co-immobilization of PEDOT and FAD using multi-walled carbon nanotubes
A simple method was used to synthesize active hybrid composites containing multi-walled carbon nanotubes (MWCNTs), poly(3,4-ethylenedioxythiophene) (PEDOT) and flavin adenine dinucleotide (FAD). The MWCNT/PEDOT–FAD hybrid composite had good electrocatalytic properties for ascorbic acid, dopamine, uric acid and hydrogen peroxide compared with PEDOT, PEDOT–FAD, MWCNT/PEDOT and PEDOT–FAD/MWCNT. It had a linear concentration range of 4 × 10−4 to 8 × 10−3 M for ascorbic acid, 6 × 10−6 to 7.5 × 10−5 M for dopamine and 2 × 10−6 to 4 × 10−5 M for uric acid. The sensitivities were 36 μA mM−1 cm−2 for ascorbic acid, 5154 μA mM−1 cm−2 for dopamine and 14 286 μA mM−1 cm−2 for uric acid. The detection limits were 4 × 10−4 M for ascorbic acid, 6 × 10−6 M for dopamine and 2 × 10−6 M for uric acid (S/N = 3). It also showed good electrocatalytic reduction of H2O2 with a linear concentration range of 5 × 10−4 to 9 × 10−3 M, a sensitivity of 52 μA mM−1 cm−2 and a detection limit of 5 × 10−4 M (S/N = 3). We report here a simple method of synthesizing the active species on the surface of the electrodes for the simultaneous determination of ascorbic acid, dopamine, uric acid and H2O2. This hybrid could be used to develop multifunctional biosensors.