Spectroelectrochemical and Voltammetric Studies of <scp>L</scp>‐DOPA

Liu, Xiaoqiang; Zhang, Zheling; Cheng, Guangjin; Dong, Shaojun

doi:10.1002/elan.200390009

Cited by 48 publications

(56 citation statements)

References 12 publications

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“…The origin of the irreversible oxidation peak at about 0.6 V is presently not fully understood. In the latter case, a cathodic peak at about À 0.3 V was, however, seen on the reverse scan most likely due to the reduction of cyclodopa originating from a chemical reaction involving dopaquinone formed upon the oxidation of l-dopa [23].…”

mentioning

confidence: 86%

Voltammetric Determination of L‐Dopa on Poly(3,4‐ethylenedioxythiophene)‐Single‐Walled Carbon Nanotube Composite Modified Microelectrodes

Mathiyarasu

Nyholm

2010

Electroanalysis

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In the present communication, it is shown that platinum microelectrodes electrochemically coated with a composite of poly(3,4-)ethylenedioxythiophene and single-walled carbon nanotubes (PEDOT/SWNT) enable determinations of 3,4-dihydroxy-l-phenylalaines (l-dopa) in neutral phosphate buffer solutions containing an excess of ascorbic acid. The interpenetrated networked nanostructure of the composite was characterized by scanning electron microscope (SEM) and Raman spectroscopy. It is shown that the presence of the composite gives rise to an increase in the electroactive area of an order of magnitude in compared to the area for the bare microelectrodes. The composite filmcoated microelectrode, which yielded reversible cyclic voltammograms for the ferro/ferricyanide redox couple for scan rates between 0.01 and 0.10 V s À1, also gave rise to two well-resolved oxidation peaks for l-dopa and ascorbic acid (AA). The latter effect, which was not seen in the absence of the composite, enabled differential pulse voltammetric determinations of l-dopa in the concentration range between 0.1 to 20 mM with a detection limit of 100 nM.

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mentioning

confidence: 86%

Voltammetric Determination of L‐Dopa on Poly(3,4‐ethylenedioxythiophene)‐Single‐Walled Carbon Nanotube Composite Modified Microelectrodes

Mathiyarasu

Nyholm

2010

Electroanalysis

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“…It was found in the literature that the levodopa oxidation involves a two-electron process [29,30]. Carbidopa should obey a similar electrochemical oxidation mechanism, since its molecular structure resembles that one of levodopa and others catecholamines.…”

mentioning

confidence: 97%

Voltammetric Studies and Determination of Levodopa and Carbidopa in Pharmaceutical Products

2006

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In this paper, the possibility of analyzing levodopa and carbidopa by differential pulse voltammetry (DPV) utilizing a glassy carbon electrode in 0.1 mol L À1 HClO 4 is reported. Cyclic voltammograms of levodopa show a redox couple with anodic and cathodic peak potentials at 0.58 V and 0.52 V (vs. Ag/AgCl), respectively. For carbidopa, there are two oxidation waves with maximum currents at 0.53 V and 1.02 V, without any cathodic counterpart at slow enough scan rate. Since in such conditions, the oxidation product of carbidopa does not undergo reduction, it is possible to analyze levodopa without interference. On the other hand, carbidopa can be determined between 0.85 V and 1.1 V in the presence of levodopa, coating the electrode with a Nafion film, which is selective for carbidopa. The developed methodology was applied to two different commercial samples of pharmaceutical products. The obtained data were compared with the results of the analysis by high performance liquid chromatography (HPLC) with UV detection, showing good correlation (relative errors changing between 0.4% and 3.5%) and absence of interference of the other components that accompanied the pharmaceuticals.

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“…To convert DOPAquinone to L-DOPA again, the working potential was 129 mV for electroenzymatic L-DOPA synthesis. Liu et al [19] tested the electrochemical behavior of L-DOPA and reported the cathode and anode potential values as 576 mV and 610 mV, respectively. The authors did the experiment at an acidic pH.…”

Section: -2 Cyclic Voltammogram Of L-dopamentioning

confidence: 99%

L-DOPA Synthesis Using Tyrosinase-immobilized on Electrode Surfaces

Rahman

Gobikhrisnan

Gozan

et al. 2016

Korean Chemical Engineering Research

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− Levodopa or L-3,4-dihydroxyphenylalanine (L-DOPA) is the direct precursor of the neurotransmitter dopamine. L-DOPA is a well-known neuroprotective agent for the treatment of Parkinson's disease symptoms. L-DOPA was synthesized using the enzyme, tyrosinase, as a biocatalyst for the conversion of L-tyrosine to L-DOPA and an electrochemical method for reducing L-DOPAquinone, the product resulting from enzymatic synthesis, to L-DOPA. In this study, three electrode systems were used: A glassy carbon electrode (GCE) as working electrode, a platinum, and a Ag/ AgCl electrode as auxiliary and reference electrodes, respectively. GCE has been modified using electropolymerization of pyrrole to facilitate the electron transfer process and immobilize tyrosinase. Optimum conditions for the electropolymerization modified electrode were a temperature of 30 o C and a pH of 7 producing L-DOPA concentration 0.315 mM. After 40 days, the relative activity of an enzyme for electropolymerization remained 38.6%, respectively.

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Spectroelectrochemical and Voltammetric Studies of L‐DOPA

Cited by 48 publications

References 12 publications

Voltammetric Determination of L‐Dopa on Poly(3,4‐ethylenedioxythiophene)‐Single‐Walled Carbon Nanotube Composite Modified Microelectrodes

Voltammetric Determination of L‐Dopa on Poly(3,4‐ethylenedioxythiophene)‐Single‐Walled Carbon Nanotube Composite Modified Microelectrodes

Voltammetric Studies and Determination of Levodopa and Carbidopa in Pharmaceutical Products

L-DOPA Synthesis Using Tyrosinase-immobilized on Electrode Surfaces

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