Conducting Polymer and Zeolite Modified Carbon Electrodes for the Determination of Drugs and Biological Fluids
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Date
2013-05
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Addis Ababa University
Abstract
Electrochemical signals can be enhanced by specifically modifying electrode surfaces
with the aim of providing suitable environment to the analyte of interest. Poly(3,4-
ethylenedioxythiophene) and activated iron(JlI) doped zeolite were used to modify
carbon electrodes for the determination of drugs and biological fluids. 3,4-
Ethylenedioxythiophene was electropolymerized on glassy carbon electrode by running
multi-sweep cyclic voltammetry whereas iron(lIl) doped zeolite was coated on the
electrode surface. Both modified carbon electrodes were characterized by using cycl ic
voltammetry. The poly(3,4-ethylenedioxythiophene) modified electrodes were employed
for the determination of niclosamide and N-acetyl-p-aminophenol while the iron(JlI)
doped zeolite modified electrodes were used to determine pyridine-2-aldoxime
methochloride and uric acid. Cyclic voltammetry and differential pulse voltammetry were
used to investigate the electrochemical behavior of N-acetyl-p-aminophenol and its
degradation product, p-aminophenol at poly(3,4-ethylenedioxythiophene) modified
electrode in pH 7.0 buffer solution. Both N-acetyl-p-aminophenol and p-aminophenol
showed quasi-reversible redox reactions with formal potentials of 367 m V and 101 m V
(versus Ag/ AgCI), respectively. The significant peak potential difference (266 m V)
between N-acetyl-p-aminophenol and p-aminophenol enabled the simultaneous
III
determination of these species using differential pulse voltammetry. The voltammetric
responses gave linear ranges of 1.0- 100 /lM and 4.0- 320 /lM, with detection limits of
0.40 /lM and 1.2 /lM for N-acetyl-p-aminophenol and p-aminophenol, respectively.
Furthermore, the poly(3 ,4-ethylenedioxythiophene) modified electrode showed a very
good electrochemical behavior for niclosamide with a significant enhancement of the
peak current compared to the bare electrode. A linear voltammetric response for
niclosamide was obtained in the concentration range 0.075- 7.50 /lM, with a detection
limit of 0.01 /lM. When the iron(lll) doped zeolite modified glassy carbon electrode was
treated with sulfuric acid (2.5 mM), it showed a better electrochemical response
compared to the untreated zeolite modified electrode. Cyclic voltammetry and square
wave voltammetry were employed to investigate the electrochemical behavior of
pyridine-2-aldoxime methochloride and uric acid at the modified electrode. The
analytical performance of the modified electrode was evaluated using anodic stripping
voltammetry in a buffer solution (PH 7.0), and a linear response for pyridine-2-aldoxime
methochloride was obtained in the concentration range 0.5-100.0 /lM with a detection
limit of 0.16 /lM. The iron(IIl) doped zeolite was also responsible for the electrocatalytic
oxidation of uric acid in a buffer solution (PH 4.6). The analytical performance of the
iron(IIl) doped zeolite modified electrode was evaluated using square wave voltammetry.
A linear anodic response for uric acid in the concentration range 0.6-6.0.0 /lM, a
detection limit of 0.09 /lM and sensitivity of 0.64 /lA /lM- 1 were obtained. Finally, the
proposed methods were successfully applied for the determination of the analytes in
pharmaceutical formulations and/or biological samples.
Description
Keywords
Determination of Drugs and Biological Fluids