Studies on novel electrochemical detection in liquid chromatography

• Published in: BUNSEKI KAGAKU Vol. 51; no. 3; pp. 199 - 200
• Main Author: SATO, Kiyohito
• Format: Journal Article
• Language: Japanese
• Published: The Japan Society for Analytical Chemistry 05.03.2002
• Subjects: amino acids; carbon film ring-disk electrode; electrochemical detection; HPLC; integrated pulsed amperometry; Ni-Ti alloy electrode; pencil lead electrode
• ISSN: 0525-1931
• DOI: 10.2116/bunsekikagaku.51.199

Electrochemical detection offers advantages of simple instrumentation, inherent sensitivity and extreme selectivity for use in HPLC. However, most amino acids cannot be detected by constant-potential amperometry at conventional carbon electrodes. Therefore, to detect amino acids and related compounds electrochemically, novel direct and indirect detection systems have been developed. First, a Ni-Ti alloy was characterized and used as a detector for the analysis of amino acids. As a result, the Ni-Ti alloy electrode exhibited a high degree of reproducibility as an electrode material due to the stability of the oxide film. Secondly, an indirect electrochemical detection method has been developed based on the use of a carbon film ring-disk electrode. This method exhibited the lower limit of detection for amino acids with large aliphatic side chains, which were very poor in sensitivity at metal electrodes. Thirdly, from the viewpoint of providing a screening method for forensic and emergency toxicology, integrated pulsed amperometry was applied to detect phosphorus-containing amino acid-type herbicides (glufosinate, bialaphos and glyphosate). Finally, the ability of pencil leads has been exploited for the electrochemical detection of phenol and chlorophenols. These varied approaches provide numerous advantages, such as simplicity, high sensitivity and reproducibility, for detecting amino acids and related compounds without prior derivatization.