Electrochemical behavior of 3,4-dihydroxyphenylalanine in aqueous solution

The electrochemical oxidation of 3,4-dihydroxyphenylalanine (l-DOPA) has been studied in various pHs using cyclic voltammetry. In this work, the effects of different parameters such as pH, l-DOPA concentration, time window of the chosen electrochemical method, and temperature on the electrochemical behavior of l-DOPA have been studied for understanding the oxidation mechanism of this compound. The experimental data presented in this work, indicate that the process of electrooxidation of l-DOPA follows an EqCiEq mechanism. The proposed following chemical reaction in EqCiEq mechanism, include a hydroxylation reaction in strong acidic pHs, both dimerization and intramolecular reactions in moderate acidic pHs and an intramolecular reaction in neutral and basic pHs. Also, the result has shown that in neutral and basic pHs, the rate of the intramolecular chemical reaction is more than that in moderate acidic pH.

► The electrochemical oxidation of l-DOPA has been studied in various pHs.
► The process of electrooxidation of l-DOPA follows an EqCiEq mechanism.
► The kinds of following chemical reactions in the EqCiEq mechanism are pH dependent.