A Raman and UV-Vis study of catecholamines oxidized with Mn(III)

Barreto, Wagner José; Ponzoni, Silvia; Sassi, Paola

doi:10.1016/s1386-1425(98)00164-4

Cited by 124 publications

(100 citation statements)

References 20 publications

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“…The characteristic dependence on the potential is similar to that of 1564 cm -1 . The downward peak at 1339 cm -1 begins at 0.29 V, and is the ν(CC) contribution from the pyrrole ring, 9 which further confirms the formation of dopaminechrome. These bands show no isotopic change upon deuteration and are comparable with other reported results.…”

Section: In-situ Ftir Spectroscopymentioning

confidence: 69%

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In-situ FTIR Spectroelectrochemical Study of Dopamine at a Glassy Carbon Electrode in a Neutral Solution

2002

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IntroductionDopamine (DA) serves as a neurotransmitter in the central and sympathetic nervous systems, or as a hormone in vesicles of the adrenal medulla for regulating the heart beat rate and blood pressure. 1 A loss of DA-containing neurons may result in some serious disease, such as Parkinson's disease. Therefore, detailed information regarding its reaction at the molecular level and a determination of the concentration of DA are important.The fact that DA and other catecholamines are easily oxidizable compounds makes their detection possible by electrochemical methods based on anodic oxidation. Several studies of electrochemical redox processes of DA have been carried out. 2,3 However, the redox process of DA is very complicated due to the formation of a series of intermediates, and the mechanism is still uncertain.In situ Fourier transform infrared (FTIR) spectroelectrochemistry is one of the useful methods to characterize the intermediates in redox processes. To our knowledge, a study of the redox pathway of DA using the in situ FTIR spectroelectrochemical method has not been reported previously. In this work the electrochemical redox processes of DA were studied by thinlayer cyclic voltammetry and an in situ FTIR technique. It is our goal to identify the absorbance characteristics of any intermediates in the electrochemical oxidation of DA and to clearly understand the reaction pathway of DA in detail. Experimental ReagentsDopamine hydrochloride was obtained from Sigma Chemical Company (USA). KCl, K2HPO4 and KH2PO4 were purchased from Shanghai Chemical Company (Shanghai), Hongxing Chemical Company (Beijing), and Xilong Chemical Company (Guangdong), respectively. All chemicals were of analytical reagent grade. All solutions were prepared in D2O and oxygen was removed by purging high-purity nitrogen. Instruments and in-situ FTIR spectroelectrochemical measurementsThe in-situ FTIR experiments were carried out on a NicoletNexus 870 spectrometer equipped with a variable-angle specular reflectance accessory (VeeMax II) and an MCT-A detector cooled with liquid nitrogen. The electrochemical equipment used was an EG&G PAR Model 283 potentiostat/galvanostat. The in situ FTIR and voltammetric measurements were performed in a spectroelectrochemical cell. The working, counter and reference electrodes were a glassy carbon electrode (EG&G), a Pt wire and an Ag/AgCl electrode, respectively. The IR transparent window was a disk of calcium fluoride, and the angle of incidence on the CaF2 window was 50˚. A total of 50 interferometric scans with a resolution of 4 cm -1 were accumulated for the spectrum, and the current was recorded simultaneously. The spectra were successively taken while the electrode potential was scanned at a rate of 2 mV s -1 . All of the IR spectra obtained are represented as ∆R/R in the normalized form according to the formulawhere R(ES) and R(Eb) are the reflected intensities measured at the sample and base potentials, respectively. Results and Discussion Thin-layer cyclic voltammogramThe thin-layer c...

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Section: In-situ Ftir Spectroscopymentioning

confidence: 69%

“…In aqueous solutions at neutral pH, the predominant chrome form would be the dipolar ion (III) in acidbase equilibrium. 9 Thus, the appearance of downward bands at 1456 and 1418 cm -1 is due to the formation of the p-quinonemine-dopaminechrome and dipolar ion dopaminechrome.…”

Section: In-situ Ftir Spectroscopymentioning

confidence: 98%

In-situ FTIR Spectroelectrochemical Study of Dopamine at a Glassy Carbon Electrode in a Neutral Solution

2002

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“…As shown in Fig. 2B, in a 0.1 M phosphate buffer solution (pH 7.17) containing 2 mg/mL DA, an intense band was observed at 282 nm (curve a), which is directly related to the symmetryforbidden transitions (L a ÀL b ) of the DA molecule [23]. The time-dependent spectra obtained during the HAuCl 4 -catalyzed oxidation of DA were shown in Fig.…”

Section: Characterizations Of Modified Pdms Microchipsmentioning

confidence: 85%

PDMS microchip coated with polydopamine/gold nanoparticles hybrid for efficient electrophoresis separation of amino acids

et al. 2011

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In this paper, a novel, simple, economical and environmentally friendly method based on in situ chemically induced synthesis strategy was designed and developed for the modification of a poly(dimethylsiloxane) (PDMS) microchip channel with polydopamine/gold nanoparticles (PDA/Au NPs) to create a hydrophilic and biofouling resistant surface. Dopamine as a reductant and a monomer, and HAuCl(4) as an oxidant to trigger dopamine polymerization and the source of metallic nanoparticles, were filled into the PDMS microchannel to yield in situ a well-distributed and robust PDA/Au NP coating. Au NPs were highly and uniformly dispersed in/on the PDA matrix with a narrow size distribution, as verified by scanning electron microscopy and UV-vis spectra. Compared with the native PDMS microchannel, the modified surfaces exhibited much better wettability, high stability and suppressed electroosmotic mobility, and less nonspecific adsorption towards biomolecules. The water contact angle and EOF of PDA/Au NP-coated PDMS microchip were measured to be 13° and 4.17×10(-4) cm(2)/V s, compared to those of 111° and 5.33×10(-4) cm(2)/V s from the native one, respectively. Fast and efficient separations of five amino acids such as arginine, proline, histidine, valine and threonine suggested greatly improved electrophoretic performance of the PDA/Au NP-functionalized PDMS microchips. This one-step procedure offers an effective approach for a biomimetic surface design on microfluidic chips, which is promising in high-throughput and complex biological analysis.

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“…27 The initially colorless solution acquired a dark green color and bands at 290 and 330 nm with 48 h of oxidation, and showed the greatest reactivity ( Figure 4B). After 48 h the absorbance of the complex at 590 nm reduced indicating a progressive deactivation of the chromogenic reagent caused by a slowing polymerization of the dopa-semiquinone.…”

Section: Reactivity Of the Chromogenic Reagentmentioning

confidence: 99%

Determination of Ni(II) in metal alloys by spectrophotometry UV-Vis using dopasemiquinone

Barreto

Scarmínio

et al. 2010

Quím. Nova

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Recebido em 12/2/09; aceito em 10/7/09; publicado na web em 13/11/09 A spectrophotometric method was proposed for Ni(II) determination in alloys using a dopa-semiquinone (L. The optimal conditions for the determination were: wavelength 590 nm, temperature 25 °C, reaction time 45 min and pH 7.5. The Beer's law was obeyed for nickel from 3.33 x 10 -5 to 1.78 x 10 -4 mol L -1. The method was applied to complex samples, such as inox, nickel-titanium and cobalt-chromium alloys. A study of the potential interferents revealed that Mn was the major interferent. The limit of detection and quantification were 2.88 x 10 -5 mol L -1 and 3.06 x 10 -5 mol L -1 , respectively.

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A Raman and UV-Vis study of catecholamines oxidized with Mn(III)

Cited by 124 publications

References 20 publications

In-situ FTIR Spectroelectrochemical Study of Dopamine at a Glassy Carbon Electrode in a Neutral Solution

In-situ FTIR Spectroelectrochemical Study of Dopamine at a Glassy Carbon Electrode in a Neutral Solution

PDMS microchip coated with polydopamine/gold nanoparticles hybrid for efficient electrophoresis separation of amino acids

Determination of Ni(II) in metal alloys by spectrophotometry UV-Vis using dopasemiquinone

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