Selective Detection of Uric Acid in the Presence of Ascorbic Acid and Dopamine Using Polymerized Luminol Film Modified Glassy Carbon Electrode

Abstract

Electrochemically polymerized luminol film on a glassy carbon electrode (GCE) surface has been used as a sensor for selective detection of uric acid (UA) in the presence of ascorbic acid (AA) and dopamine (DA). Cyclic voltammetry was used to evaluate the electrochemical properties of the poly(luminol) film modified electrode. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) have been used for surface characterizations. The bare GCE failed to distinguish the oxidation peaks of AA, DA and UA in phosphate buffer solution (pH 7.0), while the poly(luminol) modified electrode could separate them efficiently. In differential pulse voltammetric (DPV) measurements, the modified GCE could separate AA and DA signals from UA, allowing the selective determination of UA. Using DPV, the linear range (3.0 Â 10 À5 to 1.0 Â 10 À3 M) and the detection limit (2.0 Â 10 À6 M) were estimated for measurement of UA in physiological condition. The applicability of the prepared electrode was demonstrated by measuring UA in human urine samples. Uric acid (UA) is the ultimate catabolite of purine metabolism in humans and higher primates. It is a weak organic acid that under physiologic conditions exists mainly as a monosodium salt. At a pH less than 5.75, as may occur in the urine, the predominant form is nonionized UA. The solubility of monosodium urate is about 18 times greater than UA in aqueous solutions. This solubility difference provides the therapeutic rationale for alkalinization of the urine pH to greater than 6.0 in patients forming UA stones. UA levels are influenced by age and sex. Many additional factors, including exercise, diet, drugs, and state of hydration, may result in transient fluctuations of UA levels. Extreme, abnormal levels of UA in body fluids will lead to some diseases. It is for this reason, that simple and rapid detection methods are required [1 -3].Detection of biological molecules using chemically modified electrodes is more attractive strategy since electrochemical sensors combines the specificity of biological or chemical recognition layers with the inherent advantages (sensitivity, speed, miniaturization, linearity) of electrochemical transduction [4 -6]. Polymer modified electrodes (PMEs) are received considerable attention among the researchers for sensing applications. Electropolymerization is a good approach to prepare PMEs as adjusting electrochemical parameters can control film thickness, permeation and charge transport characteristics [6 -8].Dopamine (DA), UA and ascorbic acid (AA) usually coexist in physiological samples and these molecules have a same oxidation potential on the unmodified solid electrodes. Therefore it is essential to develop a simple and rapid method for their determination in routine analysis. Among many methods for determination of UA in biological samples, voltammetric method has shown to be a powerful tool [9,10]. Recently, edge plane pyrolytic graphite electrodes [11], Ir-modified carbon working electrode with immobilizing uricase [12], hexacyanofe...

A Novel Electrochemical Sensor Based on a Mixed Diazonium/PEDOT Surface Functionalization for the Simultaneous Assay of Ascorbic and Uric Acids. Towards an Improvement in Amperometric Response Stability

“…For UA, our results were very close to those reported by Kumar et al. 24 who also used CV, but were found to be far below the ones found by using the more sensitive SWV and DPV as the detection mode. The limits of detection for both acids also compared well with literature data.…”

Voltammetric microsensor using PEDOT-modified gold electrode for the simultaneous assay of ascorbic and uric acids

“…In consequence, in contrast with several previous published papers indicating that AA induced no interference in the assay of UA (sometimes in contradiction with the experimental results presented, see for example Ref. [26,28,33]), an obvious change was observed in our case in the UA oxidation current depending on whether AA was present in the sample or not. Consequently two different protocols have to be practically adopted depending on the composition of the samples: in the case, where all samples contain AA (particularly if in large excess), the assay of UA would induce no bias provided that the calibration curve is performed in the presence of AA.…”

“…Chemically modified electrodes have been particularly developed to discriminate between the electrochemical responses of AA and UA oxidation. Several electrode modification processes have been tested, using highly oxidized metal electrodes [16], metal electrodeposition [17], metal complexes [18,19], electrochemical reduction of diazonium salts [20], mesoporous silica [21], single [22] or multiwalled carbon nanotubes [23], self-assembled thiol monolayer [24], ion-exchange Nafion membrane [25] or conducting polymers like poly vinyl alcohol [26], polypyrrole [27] or luminol [28] for measurements in rat brain [29] or in human urine and serum samples [30]. All these studies allowed the simultaneous detection and determination of AA and UA under similar concentrations [31][32][33] or the assay of UA in samples containing a large excess of AA [34][35][36].…”

Synthesis, characterization, and application of silver nanoparticle‐thiophenol nanocomposite film on the glassy carbon surface

“…Bare GC exhibited broad anodic peak and low peak current. At [39] Nafion/multi-wall carbon nanotubes composite film-modified electrode 0.1 M NaCl DPV 8.00E-05 [40] Poly(N,N-dimethylaniline) film-coated GC electrode 0.2 M phosphate buffer SWV 1.25E-6 [41] Polymerized luminol film modified glassy carbon electrode 0.1 M PBS DPV 2.00E-06 [64] Chitosan-multiwall carbon nanotube modified electrode 0.1 M phosphate buffer DPV 7.5E-7 [65] Carbon nanotube electrode 0.1 M PBS DPV 1.00E-07 [45] L-Cysteine self-assembled gold electrode 0.1 M phosphate buffer DPV 2,00E-06 [66] GC/TP/SNP/PhNH2 0. wileyonlinelibrary.com/journal/sia the GC/TP/SNP/PhNH 2 electrode, the peak currents were significantly higher than bare GC (Fig. 10).…”