Objectives: The aim was to modify carbon electrodes with (p-aminobenzene sulfonic acid) and use them as a sensor for sensitive and reliable detection of methyldopa (MD) and ascorbic acid.
Materials and Methods: Electropolymerization was performed by cyclic voltammetry in 0.1 M KCl solution. The modified sensor has a high electrocatalytic effect for oxidation of MD, which appeared in the pH range of 2-11 by differential pulse voltammetry (DPV) techniques.
Results: For the voltammetric determination of MD, the best results were acquired by DPV in phosphate buffer solution (PBS) (pH 3). The calibration plot of the proposed sensor is linear in two concentration ranges of 1.0-30 and 30.0-300.0 mu M. The calibration equations over these ranges are I-pa (mu A)=1.21xC (mu M)+30.81, R-2=0.994 and I-pa (mu A)=0.53xC (mu M)+53.30, R-2=0.9975, respectively. In the sensitivity studies, the limit of quantification and the limit of detection were 10.6 nM and 5.0 nM, respectively. The modified sensor was used for the simultaneous determination of interfering substances such as MD and ascorbic acid in real samples.
Conclusion: The obtained results revealed that the prepared modified electrode and the proposed method have good sensitivity, repeatability, reproducibility, and stability.