Electrochemical oxidation of glycine by doped nickel hydroxide modified electrode

The electrocatalytic oxidation of glycine by doped nickel hydroxide modified electrodes and their use as sensors are described. The electrode modification was carried out by a simple electrochemical co-precipitation and its electrochemical properties were investigated. The modified electrode presented activity for glycine oxidation after applying a potential required to form NiOOH (∼0.45 V vs Ag/AgCl). In these conditions a sensitivity of 0.92 μA mmol−1 L and a linear response range from 0.1 up to 1.2 mmol L−1 were achieved in the electrolytic solutions at pH 12.6. Limits of detection and quantification were found to be 30 and 110 μmol L−1, respectively. Kinetic studies performed with rotating disk electrode (RDE) and by chronoamperometry allowed to determine the heterogeneous rate constant of 4.3 × 102 mol−1 L s−1, suggesting that NiOOH is a good electrocatalyst for glycine oxidation. NiOOH activity to oxidize other amino acids was also investigated.