Journal
ELECTROCHIMICA ACTA
Volume 194, Issue -, Pages 187-198Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.electacta.2016.02.086
Keywords
Multiwalled carbon nanotubes; metal phthalocyanine complexes; modified electrode; pesticides
Categories
Funding
- CNPq [400223/2014-7, 303596/2014-7, 573636/2008-7]
- Sao Paulo Research Foundation (FAPESP) [2012/10947-2, 2014/06704-2]
- INCTMN [2008/57872-1]
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This study characterizes the electroanalytical behavior of the carbamate pesticide formetanate hydrochloride (FMT) at a cobalt phthalocyanine (CoPc) functionalized multiwalled carbon nanotubes (fMWCNT) modified glassy carbon electrode (CoPc-fMWCNT/GCE). Nafion (R) was used to improve solubility and dispersibility of fMWCNT. The construction of the developed electrode was characterized by high-resolution field-emission gun scanning electron microscopy, Raman spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. FMT exhibited a behavior consistent with a three-step reaction of the electrochemical-chemical-electrochemical mechanistic type at CoPc-fMWCNT/GCE (three anodic peaks at 0.26, 0.55 and 1.2 V, and two cathodic peaks at 0.35 and 0.50 V vs. Ag/AgCl/3 M KCl). Highly reproducible and well-defined peaks were obtained at the optimum experimental conditions (Britton-Robinson buffer at pH 5.0, accumulation potential 1.55 V, accumulation time 5 s, frequency 100 s(-1), amplitude 30 mV, and scan increment 3 mV). Peak currents were found to be proportional to the FMT concentrations in the range of 9.80 x 10(-8) to 3.92 x 10(-6) mol dm(-3) with a detection limit (LOD) of 9.7 x 10(-8) mol dm(-3). The modification of GCE with CoPc-fMWCNT enhanced the electrocatalytic activity and provided high sensitivity (3.51 A mol(-1) dm(3)). The developed electroanalytical methodology was successfully applied to FMT residue analysis in mango and grape samples with recoveries in the range of 94.2 +/- 4.5 to 105.7 +/- 1.8%. The proposed electroanalytical approach represents a reliable, sensitive and environmental friendly analytical alternative for determination of FMT. (C) 2016 Elsevier Ltd. All rights reserved.
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