Detection of trace levels of organophosphate pesticides using an electronic tongue based on graphene hybrid nanocomposites.
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 0.1nmolL-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.
National Laboratory for Nanotechnology in Agribusiness (LNNA), Embrapa Instrumentation, 13560-970 São Carlos, SP, Brazil; Center for Exact Sciences and Technology, Federal University of São Carlos (UFSCar), 13565-905 São Carlos, SP, Brazil.
Murilo H M
MHM
Facure
National Laboratory for Nanotechnology in Agribusiness (LNNA), Embrapa Instrumentation, 13560-970 São Carlos, SP, Brazil.
Luiza A
LA
Mercante
National Laboratory for Nanotechnology in Agribusiness (LNNA), Embrapa Instrumentation, 13560-970 São Carlos, SP, Brazil.
Luiz H C
LHC
Mattoso
National Laboratory for Nanotechnology in Agribusiness (LNNA), Embrapa Instrumentation, 13560-970 São Carlos, SP, Brazil; Center for Exact Sciences and Technology, Federal University of São Carlos (UFSCar), 13565-905 São Carlos, SP, Brazil. Electronic address: daniel.correa@embrapa.br.
Daniel S
DS
Correa
D062609:Electronic Nose; D006108:Graphite / Q000737:chemistry*; D057230:Limit of Detection; D053761:Nanocomposites / Q000737:chemistry*; D009943:Organophosphorus Compounds / Q000032:analysis*; D010575:Pesticides / Q000032:analysis*; D015203:Reproducibility of Results
D009943:Organophosphorus Compounds; D010575:Pesticides; D006108:Graphite
Electronic tongue; Impedance spectroscopy; Nanocomposite; Organophosphate pesticides; Reduced graphene oxide