Voltammetric determination of methionine in the presence of tryptophan based on a CeO2-ZnO nanocomposite/ethyl 2-(4-ferrocenyl[1,2,3]triazol-1-yl) acetate/1-butyl-3-methylimidazolium hexafluorophosphate modified carbon paste electrode

This study was designed to modify a carbon paste electrode (CPE) by CeO2-ZnO nanocomposite, ethyl 2-(4-ferrocenyl[1,2,3]triazol-1-yl) acetate (EFTA), and 1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6) ionic liquid. The prepared electrode (CeO2-ZnO/EFTA/BMIM-PF6) was used for the voltammetric determination of methionine (Met). The cyclic voltammetry, differential pulse voltammetry (DPV) and chrono-amperometric analyses were used respectively to evaluate and measure the electrochemical properties of Met. The CeO2-ZnO/EFTA/BMIM-PF6/CPE showed high electrocatalytic feature for Met oxidation. The obtained linear oxidation peak currents for Met ranged from 0.05 to 600.0 mu M, and the limit of detection of 0.015 mu M. Also, the modified CPE was used for the determination of Met in the presence of tryptophan (Trp). In co-existence system containing Met and Trp, the developed sensor exhibited well-defined and separate DPV peaks (i.e., 180 mV) for Met and Trp. Additionally, the applicability of this sensor was confirmed by the detection of Met and Trp in real specimens, with acceptable recoveries.