Preconcentration step is one of the necessary conditions for
enhancement of sensitivity determination. The accumulation time was
applied for preconcentration of BPR at the surface of CPE. The influence
of the accumulation time on the electrochemical response of BPR was
investigated.With increasing accumulation time, the response current
increased up to 120 s continuously. But then the more increase of accumulation
time has no remarkable effect on the oxidation peak current
due to saturation surface of electrode for BPR adsorption. So, by considering
the use of relatively short time, 120 swas selected as the optimum
accumulation time.
The effect of instrumental parameters such as pulse height (H step)
and scan rate on the sensitivity of BPR determination was also checked.
Fig. 3A illustrates the effect of H step on the electrochemical response of
BPR at CPE. As shown, themaximumpeak currentwas obtained at an H
step of 0.01 V and after that the peak current of BPR is almost independent
of H step. Therefore, this value was applied for the determination
of BPR in this work.
The effect of scan rate on the oxidation peak current of 0.08 μMBPR
was investigated in the 0.01–0.11 V s−1 range of scan rate (Fig. 3B). As
shown in the inset of Fig. 3B, the value of peak current reaches itsmaximum
at 0.09 V s−1, and then the peak current remains constant. Thus,
this value was selected as an optimum scan rate