Electrochemical synthesis of Ni nanostructures on paper electrode for simultaneous sensing of dopamine, tryptophan and ascorbic acid

In this work we used a simple strategy for simultaneous determination of dopaminehydrochloride (Dph), tryptophan (Trp) and ascor-bic acid (AA) by electrochemical synthesis of conductive Ni nanostructures (band gap of 1.0eV) on the surface of multiwalled carbon nanotube nanocomposite modified paper electrode (NiNPs/MWCNT/PE). Scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse vol-tammetry (DPV) were used to characterize the performance and microstructure of the sensor. The diffusion coefficient (D) and the kinetic parameters such as electron transfer coefficient (α) and catalytic rate constant (k) for Dph, Trp and AA were also determined using electrochemical approaches [1]. The cyclic voltammetry method showed Dph, Trp and AA oxidation reaction with irreversible characteristics was diffusion-controlled at low scan rates. Under the optimized experimental conditions Dph, Trp and AA give linear response over the range of 0.008 - 70.0 μM, 0.006–50.0 μM and 0.01.0–40.0 μM, respectively.The lower detection limits were found to be 0.23 for Dph, 0.10 for Trp and 0.79 nM for AA. The modified electrode showed good sensitivity and stability by better response than to other reported papers [2-3].The practical application of the modified electrode was demonstrated by measuring the concentration of Dph, Trp and AA in blood serumand pharmaceutical samples.