Monoclonal antibody-based enzyme immunoassays for the sensitive detection of s-triazines in water

Immunoassays in pesticide residue analysis significantly profit from the monoclonal antibody (mAb) technology because a sufficient supply of standardised antibodies can be provided. For the production of atrazine-specific mAbs hybridoma cells were produced by fusion of mouse myeloma cells and spleen cells from mice which were immunised with 4-chloro-6-ethylamino-I ,3,5-triazine-2-(6-aminohexanoic acid) coupled to keyhole limped hemocyanin. After screening with a competitive enzyme immunoassay (EIA) a mAb with high binding affinity towards atrazine was selected. A sensitive EIA was developed detecting atrazine within a range from 0.05 to 1 jig/i with a test midpoint of 0. 1 jig/i. The mAb cross-reacts predominantly with propazine (136%). Since this herbicide is not used in most European countries, the test allows a rapid and inexpensive screening for atrazine in the ppt range. Another EllA has been constructed for the detection of terbuthylazine. The limiting factor in EIA development is the screening for cell lines secreting mAbs with high affinity and selectivity towards the analyte. Super paramagnetic beads being coated with suitable immunoconjugates are shown to bind to hybridomas presenting hapten-specific receptors on their surface. Hybndomas secreting hapten-specific mAbs can be removed by a magnet and be cloned subsequently by standard procedures. A considerable demand of mAbs is expected in the future due to new emerging techniques such as immunosensors.