a highly selective electrochemical sensor based on multi walled carbon nano tubes/poly (evans blue) composite for the determination of l-dopa in presence of 5-ht and folic acid: a voltammetric investigation

A novel and selective sensor was fabricated by electrochemical polymerization of evans blue (eb) followed by deposition of multi-walled carbon nano tubes (mwcnts) on glassy carbon electrode (gce). the developed electrode was characterized using cyclic voltammetry (cv) and electrochemical impedance spectroscopy (eis). the fabricated electrode was employed for analyzing neurotransmitter drug l-dopa and its simultaneous determination in presence of neuromodulator serotonin (5-ht) and folic acid (fa) (one of the b- vitamins) with the help of differential pulse voltammetry (dpv) technique. the effect of ph of the phosphate buffer solution (pbs) was studied and ph − 5.0 was found to be an optimum ph value. in the present investigation, the kinetic parameters, such as charge transfer coefficient, number of electrons involved and rate constant values were evaluated. the voltammetric peak currents showed a linear response for l-dopa concentrations from 0.5 to 100 µm and from the linear relationship results, the limit of detection (lod) and limit of quantification (loq) values were evaluated as 0.53 and 1.7 µm, respectively. the fabricated electrode showed good stability, reproducibility and sensitivity. the practical application of the developed sensor in determining l-dopa levels in pharmaceutical formulation and human serum samples were successfully monitored.