Fig. 2 shows the LSV responses of various concentrations
of DA in the presence of 50.0 mM ABSA pre-oxidized at
+0.65 V for 10 s. A linear dynamic range (0.1–1.0 mM)
was obtained (Fig. 2 inset) with a detection limit of
0.01 mM (S/N = 3). The determination of DA was also
examined, using square wave voltammetry (SWV) with
parameters of scan increment = 0.004 V, amplitude =
0.025 V and frequency = 15 Hz. A linear dependence with
the DA concentration (2.0–10.0 lM) was obtained (I/
lA = 0.134 [DA]/lM + 0.197; R2 = 0.9858) with a detection
limit of 0.26 lM. Note that both the linear range and
detection limit are comparable to the reported voltammetric
methods based on modified electrodes [10,11].