Modified Screen-Printed Electrodes Based on Oxidized Graphene Nanoribbons for the Selective Electrochemical Detection of Several Molecules

摘要

An electrochemical study of several molecules has been carried out, using novel graphene-modified screen printed electrodes (GN-SPEs). Different analytical parameters have been optimized, as: the graphene concentration for a homogeneous coating of the electrode surfaces, the scan rates and the potential window for the electrochemical detection of potassium ferricyanide, catechol, hexaammineruthenium(III) chloride, sodium hexachloroiridate-(III) hydrate, dopamine, epinephrine, L-tyrosine, 3,4-dihydroxyphenylacetic acid (DOPAC), ascorbic acid, uric acid, 4-acetamidophenol (acetaminophen), NADH, H _2O _2, caffeic acid, guanine, and serotonin (5-HT) hydrochloride. In addition, different experimental conditions were tested, especially the solvents used to obtain a stable graphene nanoribbon dispersion. Among these various analytes, especially good results were obtained with NADH which was detected at an applied potential of +0.44V, vs.Ag/AgCl, compared to the +0.55V at pristine SWCNT paste electrodes, [7]), and with a detection limit (of 200μM), good sensitivity (1.70μA/mM mm ~2), and good reproducibility (RSD% ranging from 3 to 20 for different SPEs used for each single point of calibration plot). Also dopamine, has been successfully detected at GN- SPEs even in the presence of an electrochemical interfering compound. Results for dopamine showed a good detection limit (of 4μM), sensitivity (17.70μA/mM mm ~2) and reproducibility (RSD% ranging from 7 to 20 for different SPEs used for each single point of calibration plot).