The effect of ascorbic acid
The electrochemical determination of DA always suffers from the interference from ascorbic acid (AA). Cyclic vol- tammetric study showed that AA is irreversible oxidized at +0.25 V in pH 4.0 buffer solution. The shape of the voltam- mograms was not changed and no new waves were observed when ABSA was added, implying no reactions happened between the oxidized AA and ABSA. However, suppression of current signal was observed by the proposed LSV and FIA method when AA was co-
existed in solution. The amount of addition product P will decrease when the homogeneous reduction of the oxidized o-DQ with AA occurred [14]. By using stronger nucleo- philes, the homogeneous reaction of o-DQ and AA would be inhibited [7]. Although there is AA interference in this study, the working approach implies a promising applica- bility for the determination of the pharmaceutical medi- cines and bio-interests.