Simultaneous Measurement of Tyrosine and Uric Acid Using a New Electrochemical Sensor Based on Modified Carbon Paste Electrode

A simple strategy for simultaneous determination of tyrosine (Tyr) and uric acid (UA) based on gold nanoparticles/graphene dot nanocomposite modified glassy carbon electrode (AuNPs/Graphene dot/CPE) is reported. Scanning electron microscopy (SEM), energy dispersive x-ray (EDX), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and square wave voltammetry (SWV) were used to characterize the performance and microstructure of the sensor. The AuNPs/Graphene dot/CPE displayed excellent electrochemical catalytic activities. SWV was carried out for the simultaneous determination of Tyr and UA in their mixture.Tyr and UA are biochemical compounds which have important roles in various biological processes. Usually, they are coexisting substances in biological matrices. Tyr is an amino acid and vital constituent of proteins, which is indispensable in human nutrition for establishing and maintaining a positive nitrogen balance [۱], Its absence could produce albinism, hypochondria, or depression. In contrast, high Tyr concentration in culture media increases sister chromatid exchange. Thus, Tyr has been of great interest [۲]. Tyr and other amino acids play roles in inducing dementia such as Alzheimer’s disease [۳]. Alteration of Tyr concentration is also related to atherosclerosis [۴] and lung diseases [۵]. UA is the primary final product of the purines metabolism in humans and abnormal levels in blood or urine cause diseases as hyperuricemia or gout [۶].The linear range of Tyr and UA were ۰.۲۴-۳۴۰ μM and ۰.۱۴-۱۴۱ μM, respectively. The limit of detection were ۰.۰۱۴ μM and ۰.۰۷ μM based on S/N=۳ by differential pulse voltammetry.The practical application of the modified electrode was demonstrated by measuring the concentrations of Tyr and UA in biological samples.The method described is a simple approach, low cost, high reproducibility, wide dynamic range, low detection limit, and high sensitivity, which makes this electrode an attractive candidate as a sensor for simultaneous measurement of Tyr and UA.