Abstract
A selective and sensitive electrochemical sensor was studied for determination of levodopa (LD) in the presence of uric acid (UA) and ascorbic acid (AA) using poly-dianix blue and multi-walled carbon nanotubes (PDB/MWCNTs) modified glassy carbon electrode. Cyclic voltammetry, differential pulse voltammetry, and chronoamperometry methods were applied to investigate the electrocatalytic oxidation of LD, UA and AA in aqueous solutions. By DPV technique, LD, UA and AA give oxidation peaks at 0.380, 0.520 and 0.180 V, respectively. Under the optimized experimental conditions LD, UA and AA give a linear response in the range of 0.09-75 μmol L-1, 0.3-110 μmol L-1 and 10-160 μmol L-1, respectively. Accordingly, the obtained detection limits were 0.003, 0.002 and 0.023 μmol L-1. The method provides a simple electrochemical sensor for successful determination of LD in human blood serum samples.
Highlights
Parkinson’s disease (PD) is a progressive neurologic disorder that leads to a slowly increasing asthenia in movement
These results indicate that the electrochemical determination of three analytes in the presence of each other on the PDB/MWCNTs- modified GCE surface is possible independently
The human blood plasma samples were collected from clinical laboratory and diluted 4 times by 0.11 mol L–1 PBS solution without any treatment. The recoveries of these three analytes in blood serum were determined by the standard addition method (Table 1) and satisfactory results were obtained. These results show that the PDB/MWCNTs-glassy carbon (GC) modified electrode is an excellent sensitive tool for simultaneous determination of the analytes in physiological samples
Summary
Parkinson’s disease (PD) is a progressive neurologic disorder that leads to a slowly increasing asthenia in movement. Whereas LD, UA and AA play the main role in the human body and often coexist in biological fluids, the selective detection of these three compounds has always been the subject of many types of research.[15] As LD, UA and AA are all electroactive, electrochemical methods are often utilized to the determination of these three species.[23,24] the direct redox reactions of these species at the bare electrodes take place at very similar potentials[25,26,27,28] and often suffer from a pronounced fouling effect, which results in a poor selectivity and reproducibility.[29,30] the voltammetric sensing of neurotransmitter metabolites usually suffers from the interference of AA, which usually coexists in vivo as anion at high concentrations and possesses an oxidation potential close to that of neurotransmitter metabolites at the unmodified electrode.[31] one promising approach for minimizing overvoltage effects and facilitating the determination is through the use of an electrocatalytic process at chemically modified electrodes. The redox active sites shuttle electrons between the analytes and the electrode shows a significant reduction in activation overpotentials
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