Determination of Tryptophan, Glutathione, and Uric Acid in Human Whole Blood Extract by Capillary Electrophoresis with a One-Step Electrochemically Reduced Graphene Oxide Modified Microelectrode

Abstract

In this work, a modified carbon fiber microdisk electrode (CFME) was created via the one-step electrochemical reduction of graphene oxide (GO) in a film on the surface of the electrode. This one-step electrochemically reduced GO-modified electrode (ERGO/CFME) displayed improved voltammetric responses to tryptophan (Trp), uric acid (UA), and glutathione (GSH) compared with those afforded by an unmodified CFME. The ERGO/CFME was used as the detector in capillary electrophoresis–electrochemical detection (CE-ECD) to separate and determine these species, and linear concentration ranges of 0.6–600 µmol L−1 for Trp, 0.8–600 µmol L−1 for GSH, and 1–600 µmol L−1 for UA were obtained using this electrode. The detection limits of this system were found to be 0.1 µmol L−1 for Trp and 0.6 µmol L−1 for GSH and UA. The ERGO/CFME showed good reproducibility, stability, and durability, and was successfully used to determine Trp, UA, and GSH in human whole-blood extracts. These results demonstrate that ERGO is a promising electrode material for use in electrochemical sensing and CE-ECD.