Abstract: A reflectometric interference spectroscopy (RIFS; reflectance interferometry) system consisting of a halogen lamp, a flow cell and a diode array detector is described; diagram given. Water containing atrazine was mixed with PBS and K4E7 atrazine mAb and incubated for 5 min. The solution was injected into a FIA system which delivered the sample to the flow cell of the RIFS system for measurement of the optical thickness of a thin transparent film. The unoccupied antibodies bind to a atrazine modified transducer surface increasing the optical thickness; the lower the atrazine content the larger the number of unoccupied antibodies. The calibration graph was produced for 0.1-5 µg/l of atrazine with a detection limit of 0.35 µg/l. There was significant cross-reactivity from simazine and terbutylazine and humic acids interfered with the determination.

Abstract: A waveguide surface plasmon resonance biosensor, equipped with low-index glass waveguides and a 10 mW He-Ne laser (632.8 nm), was evaluated for determining simazine in natural waters. The interaction length (3 mm) of the biosensor was coated with a Au film (53±3 mm thickness) and a triazine derivative, 4-chloro-6-(isopropylamino)-1,3,5-triazine-2-(6'-amino)caproic acid. The biosensor was incorporated into a FIA system and PBS of pH 7.4 was used as the carrier stream. The assays were carried out by incubating the buffered sample with simazine antibodies for 5 min. A portion (100 µL) of the solution was injected into the FIA system and the carrier stream flow was stopped for 8 min when the sample plug reacted the detector cell to allow the free antibodies to react with the immobilized triazine derivative. After recording the signal the biosensor was regenerated by pumping 2 g/l pepsin in PBS of pH 1.9 and 1% propionic acid in aqueous 50% acetonitrile. The system was calibrated for up to 100 µg/l simazine, the detection limit was 0.2 µg/l and the day-to-day RSD (n = 5) were The cross reactivities of atrazine and terbutylazine were 61% and 62%, respectively. The method was applied to surface and ground water samples and the results were confirmed by chromatographic analysis. The method was not suitable for analyzing soil water samples due to the strong non-selective polyanion-polycation binding to the transducer surface.