Fig. 5
Second-order derivative linear scan voltammograms (SDLSVs) obtained at GCE (a), PVP/GCE (b), GR/GCE (c) and PVP-GR/GCE (d) in 0.1 M phosphate buffer solution (pH 6.0) containing 1.0 mM AA, 20 μM DA and 50 μM UA. (0.0 V for the accumulation potential; 60 s for the accumulation time; 0.1 V s−1 for the scan rate)