Method development for determination of ascorbic acid, dopamine and uric acid using nanomaterial-modified screen-printed carbon electrode

Abstract

A novel electrochemical sensor was developed for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) using graphene quantum dots and ionic liquid modified screen printed carbon electrode (GQDs/IL-SPCE). GQDs were synthesized via Chen’s method and were characterized by UV-vis spectrophotometry, fluorescence spectrophotometry, and transmission electron microscopy (TEM). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed to study the electrochemical performance of the sensor. The optimum parameters for the determination of AA, DA and UA with GQDs/IL-SPCE were investigated. Well-defined oxidation peaks of the AA, DA and UA were completely separated exhibiting that GQDs/IL modifier provided excellent electrochemical catalytic activity for the oxidation of AA, DA and UA. The linear response ranges for AA, DA and UA were 25-400, 0.2-10 and 0.5-20 µM with detection limit of 6.64, 0.06 and 0.03 µM, respectively. The influence of various interferences on the selectivity of the sensor was studied. The relative standard deviations (RSD) in peak currents of AA, DA and UA were found to be 4.15%, 3.38% and 3.47%, respectively, indicating that the modified electrode had good reproducibility. The purposed method was applied to determine the amount of AA and DA in intravenous drugs with the relative error less than 5%. In addition, the satisfactory result of the sensor has been assessed in human serum sample with good recoveries (99 - 107%) using standard addition method.