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

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, H2O2, 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 +0.44 V, vs.Ag/AgCl, compared to the +0.55 V at pristine SWCNT paste electrodes, [7]), and with a detection limit (of 200 µM), good sensitivity (1.70 µA/mM mm2), 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 4 µM), sensitivity (17.70 µA/mM mm2) and reproducibility (RSD% ranging from 7 to 20 for different SPEs used for each single point of calibration plot).