Fast Wave Forms for Pulsed Electrochemical Detection of Glucose by Incorporation of Reductive Desorption of Oxidation Products

• Published in: Analytical chemistry (Washington) Vol. 69; no. 9; pp. 1776 - 1781
• Main Authors: Jensen, Mark B, Johnson, Dennis C
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.05.1997
• Subjects: Analytical chemistry; Chemistry; Chromatographic methods and physical methods associated with chromatography; Exact sciences and technology; Other chromatographic methods; Oxidation; Trace analysis; Waveform; Pulsed systems; Liquid chromatography; Desorption; Electrode pick up; Glucose; Optimization; Electrochemical storage; Electrochemical detector; Chemical reduction; Detection limit; Carbohydrate
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac960828x

The electrochemical activity of Au electrodes held at constant potential for anodic detection of carbohydrates in alkaline media eventually decays to zero. This loss of response is a consequence of the accumulation of adsorbed oxidation products on the electrode surface. Although it is well-known that these “poisons” can be removed by oxidative desorption simultaneously with formation of surface oxide, we have discovered that electrodes fouled during the detection of glucose yield a cathodic peak at −0.77 V vs SCE resulting from reductive desorption of these species. Incorporation of the reductive desorption process into wave forms for pulsed electrochemical detection (PED) permits a significant decrease in the time periods traditionally allowed for the oxidative and reductive reactivation of the electrode with a resulting increase in wave form frequency. A 6.7-Hz wave form using E red = −1.00 V (t red = 10 ms), E oxd = +0.60 V (t oxd = 10 ms), and E det = +0.10 V (t del = 50 ms, t int = 50 ms) is applied for detection of glucose in a LC-PED system and is demonstrated to yield a sub-picomole detection limit with a linear dynamic range extending over three decades.