Amino acid analysis using disposable copper nanoparticle plated electrodes

Abstract

A disposable copper nanoparticle-plated screen-printed carbon electrode (designated as Cuⁿ-SPE_100-nm) provides a new material for the determination of native amino acids. All 20 underivatized amino acids can be sensitively determined at 0.0 V vs. Ag/AgCl in pH 8 phosphate buffer solution. The precisely controlled copper nanoparticles can boost up the Cu^IIO/Cu^I₂O redox signal on the working surface without any prior pretreatment procedure. The formation of a reversible 1:1 Cu^IIO–amino acid complex on the Cuⁿ-SPE_100-nm was proposed to play a key role in the reaction mechanism. Stable detection responses were obtained for all amino acids by flow injection analysis with detection limits (S/N = 3) that lie in the range of 24 nM–2.7 µM. Selected amino acids from six representative chemical natures were separated by HPLC and detected at the Cuⁿ-SPE_100-nm with promising results.