Electrochemical behavior of oxytocin was studied using differential pulse voltammetric technique coupled with electrochemical sensor based on glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes and polyfurfurylamine as working electrodes,1.5mm Pt-wire as an auxiliary electrode and silver / silver chloride, saturated potassium chloride ( Ag/AgCl.sat KCl ) as a reference electrode.
The electrochemical behavior of oxytocin was investigated on the GCE and modified GCE through its cysteine (oxytocin component) reduction peak. Cysteine gives well defiened reduction peak at (-0.4) V versus Ag/AgCl.sat.KCl
The optimum conditions were tested for the reduction peak of cysteine, the effect of pH and the stability of the reduction peak were examined and the calibration curves of cysteine on GCE and modified GCE were constructed, a plot of peak current versus concentrations gives a straight line with r2 values 0.9938, 0.9835 and 0.9924, 0.9791 for GCE, Glassy Carbon Electrode/Poly Furfurylamine (GCE/PFA) and Glassy Carbon / Multi-Walled Carbon Nanotubes / poly Furfurylamine (GCE/MWCNTs/PFA) modified electrodes respectively. The GCE/MWCNTs/ PFA gives about three folds as much current as the GCE for a given oxytocin concentration and the slope of calibration curve equation increase according to the following sequence GCE, GCE/PFA and GCE/MWCNTs/PFA that means the sensitivity of measurements also increase in the same order .