Simultaneous Electrochemical Detection of Benzimidazole Fungicides

Jan 9, 2017 - used by planters to prevent the diverse pests and postharvest spoilage. For this reason, numerous legislations on maximum residue limits...
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Article

Simultaneous electrochemical detection of benzimidazole fungicides carbendazim and thiabendazole using a novel nano-hybrid material modi#ed electrode Yuanyuan Dong, Lijun Yang, and Lei Zhang J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.6b04675 • Publication Date (Web): 09 Jan 2017 Downloaded from http://pubs.acs.org on January 12, 2017

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Journal of Agricultural and Food Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

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Journal of Agricultural and Food Chemistry

Simultaneous electrochemical detection of benzimidazole fungicides

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carbendazim and thiabendazole using a novel nano-hybrid material

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modified electrode

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Yuanyuan Dong, Lijun Yang, Lei Zhang∗

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College of Chemistry, Liaoning University, 66 Chongshan Middle Road, Shenyang,Liaoning,

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110036, People’s Republic of China

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Abstract:

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In this work, a novel ZnFe2O4/SWCNTs nano-hybrid was successfully

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synthesized as electrode materials and applied to the simultaneous quantitative

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determination of carbendazim (CBZ) and thiabendazole (TBZ). The electrochemical

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behaviors of CBZ and TBZ on the ZnFe2O4/SWCNTs/GCE were investigated using

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cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The

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electrochemical active area of modified electrode was calculated, which is nearly 5.5

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times that of the bare electrode. The influence of various factors such as accumulation

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time, pH and scan rates, type of surfactant, and the electrochemical reaction

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mechanism were studied. The results showed that the reaction of CBZ/TBZ was

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controlled by adsorption/diffusion and was a quasi-reversible/an irreversible process

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at the ZnFe2O4/SWCNTs/GCE. In the pH 7.0 phosphate-buffered saline (PBS)

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containing 10.0 µg/mL CTAB, the electrochemical responses of CBZ and TBZ were

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separately investigated and were linearly dependent on their concentrations range

*

Corresponding author. Tel.: +86 24 62207809; Fax: +86 24 62202380. E-mail address: [email protected] (L. Zhang). 1

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from 0.5 to 100.0 µM, with relatively low detection limits of 0.09 µM and 0.05 µM,

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respectively. The concentration range for the simultaneous determination of CBZ and

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TBZ was 1.0-100.0 µM. Furthermore, with satisfactory results, the proposed

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electrochemical sensor was successfully applied to the determination of CBZ and

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TBZ in the real samples.

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Keywords:

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determination.

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Introduction

Carbendazim;

Thiabendazole;

ZnFe2O4/SWCNTs;

Simultaneous

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It is well known that there are a multitude of potential pollutants in foods,

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including different types of pesticides, mycotoxins and so on. CBZ and TBZ are

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primary compounds of the benzimidazole fungicides which are generally used in the

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crops to protect vegetables and fruits from a range of fungus and pests and provide

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quality preservation.1, 2 Most of these compounds are present in the environment after

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their use, and even some residues remain for a long time because it is difficult to

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break the ring structure of the benzimidazole.3 As a result, their residues can be also

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found in foods and environment water, which might pose a potential risk for human

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health due to their toxicity, as demonstrated by several studies.4 Hence, fungicides

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analysis in fruits/vegetables and water is of particular importance because different

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pesticides are used by planters to prevent the diverse pests and post-harvest spoilage.

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For this reason, numerous legislations on maximum residue limits (MRLs) for raw

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foods have been established, which range from 0.05 to 15.0 mg/kg for CBZ/TBZ

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depending on the different foods (such as fruits like oranges, apples, the MRL is 5.0 2

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Journal of Agricultural and Food Chemistry

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mg/kg, and the MRL of mushrooms is 1.0 mg/kg, etc.).5, 6 Consequently, the ability to

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accurately and rapidly detect trace amounts of pesticides has become more and more

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important for the health and environment protection.

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High sensitive high-performance liquid chromatography (HPLC) methods allow

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the determination of trace benzimidazole fungicides in foods.7-9 However, the HPLC

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method is more expensive and not suitable for the in situ analysis of benzimidazole

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fungicides. 10, 11 As an alternative to HPLC techniques, the electrochemical method

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has been accepted as one of the most effective tools due to its good sensitivity, low

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cost, short analytical time and easy portability.12,

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usually coexist in the same system and interfere with each other due to their similar

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structures, characteristics, and physicochemical property.14 Therefore, it is very

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interesting but it remains an important challenge for the highly sensitive and

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simultaneous electrochemical determination of CBZ and TBZ.

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Nevertheless, CBZ and TBZ

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In recent years, for the development of sensitive CBZ or TBZ, electrochemical

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sensors and some functional nanomaterials have been used. Among them, carbon

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nanotubes (CNTs) 15, 16 and their hybrids are typical examples, such as conducting

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polymer/MWCNTs modified GCE,17 mesoporous silica/MWCNTs modified-GCE,18

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MWCNT/polymeric methyl red modified-GCE,19 and cyclodextrin/graphene hybrid

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nanosheet modified GCE.20 The electrochemical response of CBZ or TBZ have been

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improved by the above mentioned sensors. However, these methods have only been

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used for the detection of individual compounds rather than for their simultaneous

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analysis. The rationally design of new sensing materials is still an urgent need to 3

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further improve the development of highly sensitive multi-pesticides sensing

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platform.

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Spinel ferrites nanoparticles (MFe2O4, M = Ni, Cu, Zn, Co, Mn) provide

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important levels of new functionality for electrochemistry owing to their greater

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electronic

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electrochemical activity.21 Among them, ZnFe2O4 might be a promising electrode

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modifier due to its low toxicity, low cost and easy preparation. Moreover, Zn and Fe

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have excellent electrocatalytic activity which can improve electrochemical properties

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of CNTs.22 Although many investigators have reported the preparation methods of

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magnetic CNTs and their applications in many fields, only a few of them have applied

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these composites to electrochemical sensors.23-25

conductivity,

effective

mass

transport,

high

surface

area

and

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In this work, ZnFe2O4/SWCNTs nano-hybrid has been successfully designed and

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synthesized through a facile one-step hydrothermal method and used as a modified

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electrode material for simultaneous determination of CBZ and TBZ. Meanwhile, the

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experimental results indicated that the voltammetric responses of CBZ and TBZ were

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found to be greatly enhanced in the presence of CTAB. The combination of SWCNTs

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with ZnFe2O4 can provide excellent electrochemical platforms for two benzimidazole

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fungicides due to the combination of strong adsorptive capability and enlarged active

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surface area in the real samples analysis.

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Experiment.

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Reagents and chemicals. SWCNTs (length: 5−30 µm; specific surface

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area: >380 m2/g; outer diameter: