Elsevier

Talanta

Volume 167, 15 May 2017, Pages 59-66
Talanta

Detection of trace levels of organophosphate pesticides using an electronic tongue based on graphene hybrid nanocomposites

https://doi.org/10.1016/j.talanta.2017.02.005Get rights and content
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Highlights

  • A free-enzyme electronic tongue based on reduced graphene oxide detects organophosphorate pesticides.

  • The system can identify different concentrations of pesticides at trace levels.

  • Mixtures with two organophosphate pesticides can be discriminated by the sensor array.

  • Variations in the concentration of pesticides in a mixture can be analyzed.

  • Real samples can be distinguished at a nanomolar concentration range.

Abstract

Organophosphate (OP) compounds impose significant strains on public health, environmental/food safety and homeland security, once they have been widely used as pesticides and insecticides and also display potential to be employed as chemical warfare agents by terrorists. In this context, the development of sensitive and reliable chemical sensors that would allow in-situ measurements of such contaminants is highly pursued. Here we report on a free-enzyme impedimetric electronic tongue (e-tongue) used in the analysis of organophosphate pesticides comprising four sensing units based on graphene hybrid nanocomposites. The nanocomposites were prepared by reduction of graphene oxide in the presence of conducting polymers (PEDOT:PSS and polypyrrole) and gold nanoparticles (AuNPs), which were deposited by drop casting onto gold interdigitated electrodes. Impedance spectroscopy measurements were collected in triplicate for each sample analyzed, and the electrical resistance data were treated by Principal Component Analysis (PCA), revealing that the system was able to discriminate OPs at nanomolar concentrations. In addition, the electronic tongue system could detect OPs in real samples, where relations between the principal components and the variation of pesticides in a mixture were established, proving to be useful to analyze and monitor mixtures of OP pesticides. The materials employed provided sensing units with high specific surface area and high conductivity, yielding the development of a sensor with suitable stability, good reproducibility, and high sensitivity towards pesticide samples, being able to discriminate concentrations as low as 0.1 nmol L−1. Our results indicate that the e-tongue system can be used as a rapid, simple and low cost alternative in the analyses of OPs pesticide solutions below the concentration range permitted by legislation of some countries.

Keywords

Electronic tongue
Impedance spectroscopy
Organophosphate pesticides
Reduced graphene oxide
Nanocomposite

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