Investigation of Voltammetric Behavior of 3-Nitro-Tyrosine and Tyrosine at Glassy Carbon and Carbon Paste Electrodes

Nitro-tyrosine is produced via tyrosine nitration by reactive nitrogen species such as peroxynitrite and NO2. Nitrotyrosine presence in the body is an indicator for cell damage and inflammation issue. Hence, the monitoring of this biomarker is an important task. Since nitro-tyrosine is produced from tyrosine, these two molecules are present concurrently in the real samples. In this work electrooxidation of nitro-tyrosine and tyrosine was checked on glassy carbon and carbon paste electrodes (CPE) utilizing cyclic voltammetry and differential pulse voltammetry methods. It was found that nitro-tyrosine creates an oxidation signal at the GC electrode, whereas, no significant oxidation peak was found for tyrosine in the GC electrode. In the case of CPE, However, both nitro-tyrosine and tyrosine showed oxidation peaks which were separated by about 0.1 V/Ag/AgCl. Applying DPV led to better resolution of oxidation peaks of tyrosine and nitro-tyrosine. Moreover, the separation of the peaks was improved when DPV was replaced with CV.  Solution pH and the binder content of the carbon paste electrode were optimized in order to achieve maximum signal for both compounds. The calibration curves were established utilizing CPE and DPV techniques.