Immunochromatographic Assay with Photometric Detection for Rapid Determination of the Herbicide Atrazine and Other Triazines in Foodstuffs

An immunochromatographic system for detection of the herbicide atrazine and its structural analogues has been developed. The assay is based on the competition of atrazine and immobilized atrazine-protein conjugate for binding with anti-atrazine monoclonal antibodies. The antibodies are immobilized on colloidal gold particles with an average diameter of 30 nm under conditions providing stability of these complexes. Concentrations of reagents and regimens of their immobilization have been optimized in order to reach the minimal limit of atrazine detection. The assay is initiated by contact of the test strip with a liquid sample and does not need any additional reactants or treatment. Duration of the assay was 10 min. The colored line formed on the test strip was assessed quantitatively with a portable photometric device; the RSD in a series was 4.8-13.0%. The range of photometrically determined concentrations of atrazine was 1-30 ng/mL. Visual qualitative assay permitted detection of the disappearance of the colored line for atrazine concentrations starting at 100 ng/mL. Cross-reactivities of structurally similar herbicides correlated well for the proposed assay and traditional microplate ELISA. The applicability of the developed system for atrazine detection in milk and juices was confirmed.