Oriented antibody immobilization for atrazine determination by a flow-through fluoroimmunosensor

An atrazine flow-through fluoroimmunosensor was developed, based on an orie nted antibody covalently bound to Protein-A (Prot-A) immobilized on Control led Pore Glass (CPG). Atrazine was detected "in-situ" by placing the immobi lized antibody in the optical path of the flow cell. Immobilization of 30 m u g of polyclonal anti-atrazine antibody on 0.5 g of Prot-A-CPG provided th e highest sensitivity. The effect of several solvents on the covalently imm obilized antibodies regeneration was evaluated, the optimum conditions bein g achieved by pumping 5% acetonitrile (pH = 3) at 0.15 mL/min for 100 s. Th e detection limit of the immunosensor was 0.7 mu g/L and the reproducibilit y was 2% and 4% for 5 mu g/L and 40 mu g/L, respectively, in the optimum wo rking concentration range (0.7-50 mu g/L). This device allowed 12 samples p er hour to be analyzed and had a life-time of 200 assays. Simazine and desi sopropylatrazine (DIA) were not cross-reactive, desethylatrazine (DEA) has a cross-reactivity of 8% and propazine and prometryn of 44% and 27%, respec tively. The immunosensor was applied to the determination of atrazine in ta p and ground water samples spiked at the 10 and 30 mu g/L concentration lev el.