Amperometric Determination Of Dopamine Research Articles

Molecularly imprinted silica films prepared by electroassisted deposition for the selective detection of dopamine

Dopamine (DA) can be detected by electrochemical oxidation in conventional electrodes. However, the presence of other oxidizable species (interferents) usually present in physiological fluids at high concentrations (like ascorbic acid) makes very difficult its electrochemical detection. In the present work, glassy carbon electrodes have been modified with molecularly imprinted silica (MIS) films prepared by electroassisted deposition of sol–gel precursors. The production of MIS films was performed by adding the template molecule (DA) to the precursor sol. The molecular impression of silica was assessed showing a high coherency allowing a filtering capacity in the molecular scale. The MIS-modified electrodes present a high selectivity for the detection of DA in neutral or acidic solutions. The MIS-modified electrodes allow the amperometric determination of dopamine in solutions containing ascorbic acid with molar ratios lower than 1:50,000.

Prussian Blue/Reduced Graphene Oxide Composite for the Amperometric Determination of Dopamine and Hydrogen Peroxide

Prussian blue has significant application for the construction of electrochemical biosensors. In this work, Prussian blue-reduced graphene oxide modified glass carbon electrodes were successfully fabricated using electrochemical deposition. The high surface area of graphene oxide enhanced the deposition of Prussian blue and the resulting electrocatalytic activity. Infrared spectroscopy and scanning electron microscopy showed that the relatively porous Prussian blue was on the surface of reduced graphene oxide. Cyclic voltammetry showed that Prussian blue-coated reduced graphene oxide composite films improved electron transfer compared to Prussian blue films. The Prussian blue-reduced graphene oxide composite film provided higher response for the reduction of hydrogen peroxide and the oxidation of dopamine compared with the Prussian blue film due to synergistic effects between the reduced graphene oxide and Prussian blue particles. The sensitivity of the electrode was 0.1617 µA µM−1 cm−2. The linear dynamic range extended from 0.5 µM to 0.7 mM dopamine with a limit of detection equal to 125 nM. This work provided a versatile strategy for the design and construction of sensitive amperometric sensors with robust electrocatalytic behavior.

A Novel Polyaniline–Poly(3-Methylthiophene)–Poly(3,3′-Diaminobenzidine) Electrode for the Determination of Dopamine in Human Serum

A polyaniline–poly(3-methylthiophene)–poly(3,3′-diaminobenzidine) film was deposited on a platinum disc electrode in dichloromethane containing tetrabuthylammonium perchlorate supporting electrolyte and used for the amperometric determination of dopamine. At a pH of 2.0, this electrode allowed successful determination at a lower potential than the oxidation potential of dopamine. The limit of detection, limit of quantification, and the linear dynamic range were determined to be 1.63 × 10−5 mM, 5.43 × 10−5 mM and 5.43 × 10−5 to 100.0 mM (R2 = 0.997), respectively. The reproducibility was investigated by using three different films and good analytical results were obtained. In addition, the modified electrode was successfully employed to determine dopamine in human serum with good recoveries.

Facile Synthesis of Graphene-poly(styrene sulfonate)-Pt Nanocomposite and Its Application in Amperometric Determination of Dopamine

Abstract Graphene-poly(styrene sulfonate)-Pt nanocomposite (GN-PSS-Pt) was synthesized with the mixture of graphene oxide and chloroplatinic acid by microwave treatment. The nanocomposite was characterized by Transmission electron microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy, respectively. The electrochemical behaviour of dopamine on the nanocomposite was investigated. A chronoamperometry method was developed for the determination of dopamine. The corresponding linear range was in 2.0 × 10−7–4.0 × 10−3 M and the detection limit was estimated as 4.0 × 10−8 M (S/N = 3). Moreover, the modified electrode was applied to the determination of dopamine in human urine and serum samples.

Synthesis and Application of Graphene-Poly(styrene sulfonate)-Pt Nanocomposite in Amperometric Determination of Dopamine

在微波辅助条件下,还原石墨烯氧化物和氯铂酸,一步反应制备了石墨烯-聚苯乙烯磺酸盐-铂纳米复合物.利用透射电镜技术,X射线衍射技术和拉曼光谱技术表征了该纳米复合物的形貌和结构.研究了多巴胺在此纳米复合物上的电化学行为,并探讨了计时安培法检测多巴胺的可行性.结果表明,检测多巴胺的线性范围为2.0×10-7 ～4.0×10-3 mol/L,检出限为4.0×10-8 mol/L（信噪比S/N=3）.此外,此纳米复合物修饰电极被用于检测人血清和尿液样品中的多巴胺.

Amperometric determination of dopamine on vegetal-tissue enzymatic electrodes. Analysis of interferents and enzymatic selectivity

Abstract The amperometric determination of phenol and catechol derivatives in general, and dopamine in particular, is studied, using enzymatically modified carbon paste electrodes. Both the electrochemical behaviour of the substrates and the enzymatic selectivity of polyphenol oxidase (PPO) according to the source are taken into account. In this way, the quantification of dopamine in the presence of metabolically related compounds is carried out with reasonable accuracy. Fresh tissues of pear, peach, mushroom and potato are used as the enzymatic source. For fresh mushroom PPO, apparent Michaelis-Menten constants ( K ′ M ) for each substrate are determined electrochemically. Purified mushroom PPO is used for comparative purposes. The effect of the substituent group of catechol derivatives on the enzymatic affinity was also analysed.

Amperometric determination of dopamine on an enzymatically modified carbon paste electrode

The amperometric determination of dopamine under controlled convective conditions on an enzymatically modified carbon paste electrode was studied using potato tissue as a source of polyphenol oxidase. Enzymatic kinetic constants and substrate diffusional-resistance parameters were determined and an analysis of the most common interferents was made. It is concluded that the electrode is suitable for the quantification of dopamine with a detection limit as low as 2.5 × 10−6 M when the hydrodynamic conditions are carefully controlled. The electrode is active towards dopac, ascorbic acid and pyrocatechol but not l-tyrosine, l-dopa, homovanillic acid, adrenaline, normetanephrine and vanilmandelic acid.