Covalent organic framework film as an effective electrocatalyst for the simultaneous determination of dihydroxybenzene isomers in water samples

Abstract

Sensitive determination of environmentally hazardous dihydroxybenzene isomers (DHBIs) by both simultaneously and selectively using the 3,5-diamino-1,2,4-triazole-CO covalent organic framework (DAT-COF) film modified glassy carbon electrode (GCE/DAT-COF) was described. The DAT-COF was synthesized by refluxing DAT and terephthalaldehyde in DMF. It was then modified on GCE by potentiodynamic method in the presence of dispersed DAT-COF. The formed DAT-COF film was confirmed by XPS, SEM and cyclic voltammetry. The SEM study revealed that the electrodeposition of DAT-COF on GC substrate leads to the formation of agglomerated structure. The electrochemical impedance studies show that the electron transfer rate constant of [Fe(CN)6]3−/4− couple at GCE/DAT-COF was higher than bare GCE. The GCE/DAT-COF was then successfully used to resolve the voltammetric signals of DHBIs, hydroquinone (HQ), catechol (CC) and resorcinol (RC) in a mixture whereas bare GCE failed to separate them. The modified electrode was successfully used to determine the three isomers from 0.20 to 500 μM and the LOD was found to be 0.13, 0.07 and 0.08 μM for HQ, CC and RC (S/N = 3), respectively. The selective determination of one isomer containing the other two isomers and also in the presence of possible other interferences including nitro compounds were achieved. Finally, the three isomers were successfully determined in different water samples.