Electrochemical Detection of Underivatized Amino Acids with a Ni-Cr Alloy Electrode

A nickel-chromium (80:20) alloy is employed as electrode material in the amperometric detection of underivatized amino acids in flow injection and high performance liquid chromatographic experiments. Cyclic voltammetric results show that amino acids are oxidized by a surface catalyzed process, proposed to involve Ni(III) oxyhydroxides, which are formed on the electrode surface at approximately 0.43 V (Ag/AgCl reference electrode) in 0.10 N NaOH. The hydrodynamic voltammograms of different amino acids show current plateaus at potentials above ca. 0.48 V. Preliminary HPLC experiments show that the nickelchromium alloy is useful for the amperometric detection of underivatized amino acids following anion exchange separations.