Electrochemical detection of uric acid and ascorbic acid: Application in serum

• Good selectivity and sensitivity for ascorbic acid and uric acid in chemical environment and serum during the detection by the Sonogel electrodes modified with l-cysteine.
• The intensity of the current shows a linear increase with UA and AA concentration in the range from 10− 5M to 10− 4M for UA and 5 × 10− 5M to 10− 3M for AA, with a correlation coefficient of 0,9909 and a detection limit of 10− 5M for UA, and with a correlation coefficient of 0, 9958 and a detection limit of 5 × 10− 5M for AA
• The SWV peak currents obtained in mixture increased linearly on the UA and AA in the range of 1 × 10− 5 to 10 × 10− 5 mol/L and 6 × 10− 4 to 2.75 × 10− 3 mol/L respectively
• For UA and AA in mixture, one can separate one from the other with a potential difference of 295 mV, which is large enough to allow the determination of one in presence of the other

The detection and quantification of uric acid (UA) and ascorbic acid (AA) in different biological fluids such as serum is very important in clinical diagnosis. In this study, a sonogel–carbon electrode modified with l-cysteine was used for detection and quantification of these molecules by cyclic voltammetry (CV) and square wave voltammetry (SWV). These two methods are known for their suitability for monitoring of bioactive molecules in biological samples. Optimization of parameters affecting selectivity and sensitivity of these two methods is included. The peak current showed a linear relationship with the concentrations of UA and AA in the range of 10− 5 M to 10− 4 M for UA and 5 × 10− 5 M respectively. The detection limit was of 10− 5 M for UA and 5 × 10− 5 M for AA. In addition, the interference of UA and AA was also studied. A neat separation of the oxidation peaks of these two compounds with a peak-to-peak separation of 295 mV was registered. The results indicate that carbon electrode modified with l-cysteine can successfully be used for a selective and sensitive simultaneous determination of UA and AA in the serum.