A Carbon Paste Electrode Modified by Bentonite and l-Cysteine for Simultaneous Determination of Ascorbic and Uric Acids: Application in Biological Fluids

A novel modification of a paste carbon electrode by Bentonite (Bent) and l-Cysteine (l-Cyst) was carried out for uric acid (UA) and ascorbic acid (AA) detection and quantification. Morphological and compositional characterization of the electrode surface were carried out using electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopic analysis (EDS). Cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques were used to analyze UA and AA. The obtained sensor shows a good stability, sensibility, selectivity, and regeneration ability. Accordingly, the limit of detection (LOD) is found to be 0.031 mu m and 9.6 mu m for UA and AA, respectively. A good linearity in the range of 0.1 to 100 mu m for UA and 10 to 1000 mu m for AA was obtained. The peak-to-peak separation of UA-AA (Delta EUA-AA) was determined to be 330 mV. In addition, the sensor is applied successfully to monitor UA and AA in serum samples.

Automated summary

A novel modification of a paste carbon electrode using Bentonite and l-Cysteine was developed for the detection and quantification of uric acid and ascorbic acid. The electrode surface was characterized using electrochemical impedance spectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopic analysis. The sensor exhibited good stability, sensitivity, selectivity, and regeneration ability, with a limit of detection of 0.031 μm for uric acid and 9.6 μm for ascorbic acid. The sensor showed good linearity in the concentration range of 0.1-100 μm for uric acid and 10-1000 μm for ascorbic acid. The peak-to-peak separation of uric acid and ascorbic acid was determined to be 330 mV. The sensor was successfully applied for the monitoring of uric acid and ascorbic acid in serum samples.