Figure 13: Cyclic voltammograms responses of: (a) bare GCE in PBS (pH 7.0), 10-2 M AA alone and 10-2 M AA + different volume of 10-4 M DA solutions; (b) GCE-MWCNT-ZnO, and (c) GCE-MWCNT-NiO in (i) 0.1M pH 7.0 PBS (ii) 10-2 M AA alone, (iii) mixture of 9.09 mM AA/9.09 µM DA, (iv) mixture of 8.33 mM AA/16.7 µM DA (v) mixture of 7.69 mM AA/23.0 DA µM (vi) 7.14 mM AA/28.6 µM DA (vii) 6.67 mM AA/33.0 µM DA (viii) 6.25 mM AA/37.5 µM DA (ix) 5.88 mM AA/41.2 µM DA (x) 5.56 mM AA/44.0 µM DA (xi) 5.2 mM AA/47.0 µM DA and (xii) 5 mM AA/50 µM DA concentrations.