Part per trillion determination of atrazine in natural water samples by a surface plasmon resonance immunosensor

8 pages, 5 figures.-- PMID: 17393154 [PubMed].-- Printed version published in May 2007.A new immunoassay for continuously monitoring atrazine in water has been developed. It uses a portable biosensor platform based on surface plasmon resonance (SPR) technology. This immunoassay is based on the binding inhibition format with purified polyclonal antibodies, with the analyte derivative covalently immobilized on a gold sensor surface. An alkanethiol self-assembled monolayer (SAM) was formed on the gold-coated sensor surface in order to obtain a reusable sensing surface. The low detection limit for the optimized assay, calculated as the concentration that produces a 10% decrease in the blank signal, is 20 ng/L. A complete assay cycle, including regeneration, is accomplished in 25 min. Additionally, a study of the matrix effects of different types of wastewater was performed. All measurements were carried out with the SPR sensor system (β-SPR) commercialised by the company Sensia, S.L. (Spain). The small size and low response time of the β-SPR platform would allow it to be used in real contaminated locations. The immunosensor was evaluated and validated by measuring the atrazine content of 26 natural samples collected from Ebro River. Solid-phase extraction followed by gas chromatography coupled to mass spectrometric detection (SPE–GC–MS) was used to validate the new immunoassay.This work was funded by the EU Project SWIFT WFD (Contract SSPI-CT-2003-502492) and the Ministry of Science and Technology (project number CTM2005-24255E and Contract number TEC20004-0121-E) and by the European Community (IST-2003-508774). The AMR group is a consolidated Grup de Recerca de la Generalitat de Catalunya and has support from the Departament d’Universitats, Recerca i Societat de la Informació de la Generalitat de Catalunya (expedient 2005SGR 00207). Marinella Farré thanks the Juan de la Cierva Program of the Ministerio de Educación y Ciencia, and Javier Ramón thanks the I3P program of the CSIC.Peer reviewe