Polycrystalline diamond electrodes: basic properties and applications as amperometric detectors in flow injection analysis and liquid chromatography

Abstract

Diamond films, fabricated by chemical vapor deposition, provide electrochemists with an entirely new type of carbon electrode that meets the requirements of activity, conductivity, and stability for a wide range of applications. In this manuscript, the basic electrochemical properties of high quality diamond thin-films (3-6 μm thick) are highlighted. The films are polycrystalline, hydrogen terminated and doped with boron (ca. 10 19–10 20 cm −3). Some preliminary results using diamond in amperometric detection schemes, coupled with flow injection analysis and liquid chromatography, are presented for azide and nitrite, chlorpromazine, ascorbic acid and catecholamines. The use of diamond for the voltammetric detection of trace metal ions is also illustrated. The detector figures of merit (e.g., dynamic range, sensitivity, detection limit, response variability and response stability) for diamond are compared with freshly polished glassy carbon. Diamond exhibits as good or superior detector performance for each of these analytes. For example, the detection limit ( S/ N = 3) for chlorpromazine at diamond is 4 nM or 26 pg, and the response variability is 0.3%, while for glassy carbon the detection limit ( S/ N = 3) is 40 nM or 260 pg, and the response variability is 1%. The properties of diamond electrochemical interfaces are far from being fully understood, but the results reported herein portend the favorable possibilities for applications of diamond in electroanalysis.