Part per trillion level determination of isoproturon in certified and estuarine water samples with a direct optical immunosensor

An optical immunosensor coupled to a FIA system was developed and applied t o monitor isoproturon in various types of water samples. The assay is based on a solid phase fluorescence immunoassay with immobilised analyte derivat ive and free, fluorescence labelled antiisoproturon antibodies. Cross-react ivities (CRs) of linuron, diuron and chlortoluron were carried out to asses s the influence of structurally similar compounds on the response of the bi osensor. The highest CR Values were obtained for diuron, 93%, whilst chlort oluron and linuron showed values of 53 and 46%, respectively, at 0.1 mug l( -1) of cross-reactant, Detection limits of 0.01 and 0.14 mug l(-1) were ach ieved after the analysis of MilliQ and river water samples, respectively. T he validation of the biosensor was carried out analyzing Aquacheck certifie d river samples which contain different amounts of phenylurea pesticides. T his River Analyser (RIANA) prototype with an optical immunosensor can be ap plied for monitoring of isoproturon in natural river water samples. Individ ual assays are completed within 15 min including total regeneration of the transducer. (C) 2001 Elsevier Science B.V. All rights reserved.