Comparative electrochemical study of new self-assembled monolayers of 2-{[(Z)-1-(3-furyl)methylidene]amino}-1-benzenethiol and 2-{[(2-sulfanylphenyl)imino]methyl}phenol for determination of dopamine in the presence of high concentration of ascorbic acid and uric acid

摘要

The comparative electrochemical behavior of self-assembled monolayers of two Schiff’s bases,n2-{[(Z)-1-(3-furyl)methylidene]amino}-1-benzenethiol (FMAB) and 2-{[(2-nsulfanylphenyl)imino]methyl}phenol (SIMP) on a bare gold electrode (Au FMAB SAM-modifiednelectrode and Au SIMP SAM-modified electrode, respectively), was investigated by means of cyclicnvoltammetry and electrochemical impedance spectroscopy in a 0.1 mol Lu00021 KCl solution that containsn5.0 u0003 10u00023 mol Lu00021 [Fe(CN)6]3u0002/4u0002. The results revealed that the modified electrodes showed annelectrocatalytic activity toward the anodic oxidation of dopamine by a marked enhancement in thencurrent response and lower overpotential (60 and 90 mV for the Au FMAB and Au SIMPnSAM-modified electrodes, respectively) in phosphate buffer solution at pH 6.0. The Au SIMPnSAM-modified electrode was applied successfully to the determination of dopamine in the presence ofna high concentration of ascorbic acid. Selective detection was realized in total elimination of ascorbicnacid response—a method different from the ones based on the potential separations. The detection limitnof dopamine was 5.0 u0003 10u00028 mol Lu00021 in a linear range from 1.0 u0003 10u00026 to 1.2 u0003 10u00024 mol Lu00021 in thenpresence of 1.0 u0003 10u00023 mol Lu00021 ascorbic acid. The interference studies also showed that the Au SIMPnSAM-modified electrode exhibited good selectivity in the presence of a large excess of uric acid andncould be employed for the determination of dopamine in pharmaceutical formulations, plasma samplesnand human urine with adequate selectivity and precision.