Separation and Detection of Tyrosine and Phenylalanine‐derived Oxidative Stress Biomarkers Using Microchip Electrophoresis with Electrochemical Detection

A method for the determination of selected aromatic amino acid biomarkers of oxidative stress using microchip electrophoresis with electrochemical detection is described. The separation of the major reaction products of phenylalanine and tyrosine with reactive nitrogen and oxygen species was accomplished using ligand exchange micellar electrokinetic chromatography with a PDMS/glass hybrid chip. Electrochemical detection was achieved using a pyrolyzed photoresist film working electrode. The system was evaluated for the analysis of the products of the Fenton reaction with tyrosine and phenylalanine, and the reaction of peroxynitrite with tyrosine.