Amperometric detection of amines and amino acids in flow injection systems with a nickel oxide electrode

The use and characteristics of a nickel oxide electrode as a detector for amines in a flow injection system are described. The anodic electrode reaction mechanism involves a higher oxidation state of nickel maintained by the applied potential (+0.49 V vs. SCE). The electroanalytical parameters are investigated and the currents for a series of amines and amino acids are compared. Two electrode configurations are compared. The flow injection technique is shown to be suitable for buffered 25-μl samples of pH as low as 3. The linear range for glycine is 10^-6–10^-3 M with detection limits of a few nanograms.