Abstract

It is shown that iron(II) tetra-aminophthalocyanine complex electropolymerized onto a multi-walled carbon nanotube-modified basal plane pyrolytic graphite electrode greatly enhanced the electrocatalytic detetion of amitrole (a toxic herbicide), resulting in a very low detection limit (0.5 nM) and excellent sensitivity of 8.80±0.44 μA/nM, compared to any known work reported so far. The electrocatalytic detection of amitrole at this electrode occurred at less positive potential (∼0.3 V vs Ag|ACl) and also revealed a typical coupled chemical reaction. The mechanism for this response is proposed. The electrode gave satisfactory selectivity to amitrole in the presence of other potential interfering pesticides in aqueous solutions.

Highlights

  • Amitrole (3-amino-1,2,4-triazole, Figure 1a) is a toxic non-selective herbicide used to control weeds in agriculture and along railway tracks [1]

  • We explore the electrocatalytic response of amitrole at a basal plane pyrolytic graphite electrode pre-modified with acid-treated Multi-walled carbon nanotubes (MWCNTs) and electro-coated with the polymer of iron (II) tetra-aminophthalocyanine complex (FeTAPc, Figure 1b)

  • The most important observations obtained from the graphs are: (i) there is a broad and weak peak due to oxidation of amitrole on unmodified basal plane pyrolytic graphite electrode (BPPGE); (ii) the peak due to oxidation of amitrole is much larger on both BPPGE-MWCNT and BPPGE- MWCNT-poly-MTAPc and is observed at less positive potentials on the former showing that the former is a better catalyst than the MTAPc complexes for the oxidation of amitrole

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Summary

Introduction

Amitrole (3-amino-1,2,4-triazole, Figure 1a) is a toxic non-selective herbicide used to control weeds in agriculture and along railway tracks [1]. The search for highly sensitive methods for the detection of amitrole, and especially in Africa, where there is no accessible document for its regulation as herbicide in agriculture, is essential. Smart integration of carbon nanotubes with metallophthalocyanine complexes on electrode surfaces has the potential to improve the electrocatalytic response of certain analytes [5, 9,10,11]. In this communication, we explore the electrocatalytic response of amitrole at a basal plane pyrolytic graphite electrode pre-modified with acid-treated MWCNTs and electro-coated with the polymer of iron (II) tetra-aminophthalocyanine complex (FeTAPc, Figure 1b). We show that this carbon nanotube-metallophthalocyanine hybrid greatly enhances the electrocatalytic response of amitrole in the sub-nanomolar concentrations

Comparative Cyclic Voltammetric Responses Towards Amitrole
Effect of Varying Scan Rates
Chronoamperometric Studies
Selectivity Studies
Experimental Section
Apparatus
Electrode modification
Conclusions
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