Coulombimetric immunosensor for paraquat based on electrochemical nanoprobes This work is dedicated to the memory of Dr. Francisco Sanchez-Baeza.

Enrique Valera, Raül García-Febrero, Isabel Pividori, Francisco Sánchez-Baeza, M. Pilar Marco

Research output: Contribution to journalArticlepeer-review


A new electrochemical immunosensor has been developed to detect paraquat (PQ) pesticide residues in food samples. The immunosensor presented uses electrochemical nanoprobes prepared by labeling the PQ specific antibodies with CdS nanoparticles (CdSNP) and antigen biofunctionalized magnetic μ-particles. Electrochemical measurements are performed using graphite composite electrodes (GECs). After the immunochemical reaction, the CdSNP are dissolved and the metal ions released are reduced at the electrode and read in the form of current or charge signal, by the well-known anodic stripping technique. Due to the amplification effect produced by the CdSNP on the amperometric/coulombimetric signal, a very high detectability is reached. Thus, PQ can be detected with an IC50 current of 0.18 ± 0.31 μg L-1 (in PBST). The immunosensor has been implemented in analyzing PQ residues in potato samples. Combined with a suitable extraction procedure PQ can be detected with a LOD current of 1.4 μg kg-1, far below the maximum residue limit (MRL, 20 μg kg-1) established by the EU for this pesticide in most crops. Likewise, the working range was in the interval between 3.08 and 67.76 μg kg-1. Preliminary experiments demonstrate that the immunosensor presented here could be used as screening tool to distinguish between compliant and non-compliant food samples.

Original languageEnglish (US)
Pages (from-to)353-360
Number of pages8
JournalSensors and Actuators, B: Chemical
StatePublished - Apr 2014
Externally publishedYes


  • CdS nanoparticles
  • Electrochemical nanoprobes
  • Food safety
  • Immunosensor
  • Paraquat pesticide residues
  • Potato

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Instrumentation
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Electrical and Electronic Engineering
  • Materials Chemistry


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