title: An electrochemical magneto immunosensor (EMIS) for the determination of paraquat residues in potato samples.
abstract: An electrochemical magneto immunosensor for the detection of low concentrations of paraquat (PQ) in food samples has been developed and its performance evaluated in a complex sample such as potato extracts. The immunosensor presented uses immunoreagents specifically developed for the recognition of paraquat, a magnetic graphite-epoxy composite (m-GEC) electrode and biofunctionalized magnetic micro-particles (PQ1-BSAMP) that allow reduction of the potential interferences caused by the matrix components. The amperometric signal is provided by an enzymatic probe prepared by covalently linking an enzyme to the specific antibodies (Ab198-cc-HRP). The use of hydroquinone, as mediator, allows recording of the signal at a low potential, which also contributes to reducing the background noise potentially caused by the sample matrix. The immunocomplexes formed on top of the modified MP are easily captured by the m-GEC, which acts simultaneously as transducer. PQ can be detected at concentrations as low as 0.18 ± 0.09 μg L(-1). Combined with an efficient extraction procedure, PQ residues can be directly detected and accurately quantified in potato extracts without additional clean-up or purification steps, with a limit of detection (90% of the maximum signal) of 2.18 ± 2.08 μg kg(-1), far below the maximum residue level (20 μg kg(-1)) established by the EC. The immunosensor presented here is suitable for on-site analysis. Combined with the use of magnetic racks, multiple samples can be run simultaneously in a reasonable time.
authors.affiliation: Nanobiotechnology for Diagnostics (Nb4D) group, IQAC-CSIC, Jordi Girona 18-26, 08034, Barcelona, Spain.
authors.forename: Raul
authors.initials: R
authors.lastname: Garcia-Febrero
authors.forename: Enrique
authors.initials: E
authors.lastname: Valera
authors.forename: Alejandro
authors.initials: A
authors.lastname: Muriano
authors.forename: M-Isabel
authors.initials: MI
authors.lastname: Pividori
authors.forename: Francisco
authors.initials: F
authors.lastname: Sanchez-Baeza
authors.forename: M-Pilar
authors.initials: MP
authors.lastname: Marco
mesh_terms: D004563:Electrochemistry; D059022:Food Safety / Q000379:methods*; D006801:Humans; D008280:Magnetics; D010269:Paraquat / Q000032:analysis*; D010573:Pesticide Residues / Q000032:analysis*; D011198:Solanum tuberosum / Q000737:chemistry*
chemical_list: D010573:Pesticide Residues; D010269:Paraquat