Electrochemical sensor for neurotransmitters at physiological pH using a heterocyclic conducting polymer modified electrode.

We report the simultaneous determination of two neurotransmitters, norepinephrine (NEP) and serotonin (5-HT), at physiological pH using the electropolymerized film of 3-amino-5-mercapto-1,2,4-triazole modified glassy carbon (p-AMTa) electrode. A bare glassy carbon (GC) electrode fails to resolve the voltammetric signals of NEP and 5-HT due to the surface fouling caused by the oxidized products of them. However, the p-AMTa electrode not only separates the voltammetric signals of NEP and 5-HT with a potential difference of 150 mV between NEP and 5-HT but also shows higher oxidation currents for them. The simultaneous determination of NEP and 5-HT was successfully achieved at p-AMTa electrode using differential pulse voltammetry method. The amperometric current response increased linearly with increasing NEP and 5-HT concentration in the range of 1.0 × 10(-8) to 1.0 × 10(-4) M and 1.0 × 10(-8) to 5.0 × 10(-5) M, respectively, and the detection limit was found to be 1.65 × 10(-11) for NEP and 1.32 × 10(-11) M for 5-HT (S/N = 3). The p-AMTa electrode shows better recovery results for spiked NEP and 5-HT in human blood plasma samples.