Fig. 7

CVs obtained on PVP-GR/GCE in phosphate buffer solution PBS (0.1 M, pH 6.0) in the presences of 1.0 mM AA (a), 20 μM DA (b) and 50 μM UA (c) respectively by different scan rates (20, 40, 60, 80, 100, 120, 140, 160, 180, 200 mV s⁻¹)