Electrochemical Characterization of Melamine Electropolymerized in Deep Eutectic Solvents for Selective Detection of Dopamine

We report here for the first time the polymerization of melamine in three different type III deep eutectic solvents (DESs), namely ethaline, glyceline and reline. The novel DESs functionalized polymelamine (PME-DESs) modified glassy carbon electrode was compared with conventional electrolytes including sulphuric acid and neutral Cl- aqueous solution. The key effect of the potential window, the acidity of the electrolyte, concentration of melamine and Cl- and the temperature of electrolyte on the polymerization of melamine have been further studied to choose the best PME-DESs. The selected PME(ethaline) was further incorporated with hydroxyl functionalized multi-walled carbon nanotube (f-WMCNTs) and applied in selective sensing of dopamine. PME(ethaline)/f-MWCNTs/GCE demonstrated excellent electrocatalytic activity towards dopamine oxidation. The observed linear range for the detection of dopamine concentration, without interferences through differential pulse voltammetry (DPV), was from 1.0 mu M to 1.0 mM (R-2 = 0.9924), with a detection limit of 288 nM (S/N = 3). Studies proved that the modified electrode can be successfully applied for the quantitative determination of dopamine both with and without interferences.

Automated summary

This study reports, for the first time, the polymerization of melamine in three different type III deep eutectic solvents, and compares the modified electrodes with conventional electrolytes for dopamine sensing. The PME(ethaline)/f-MWCNTs/GCE showed excellent electrocatalytic activity towards dopamine oxidation, with a linear detection range from 1.0 mu M to 1.0 mM and a detection limit of 288 nM. These findings suggest that the modified electrode could be successfully applied for quantitative determination of dopamine with or without interferences.