IMMUNOLABELING OF ATRAZINE RESIDUES IN SOIL

An immunolabelling procedure was developed to detect bound pesticide residues in soil using atrazine as an example. Polyclonal antibodies directed against atrazine were raised in rabbits. Antigen-binding fragments (F(ab)) were prepared and coupled to the fluorescent stain Rose Bengal B. The dye conjugate produced a fluorescence signal which was related to the amount of atrazine found in native soil samples. Preincubation with unlabelled immunoglobulines (IgG) from preimmune sera proved to be essential for blocking unspecific binding of the antibodies which varied greatly between different samples of soil material. Labelled antibodies, whose specific binding sites had been blocked by free atrazine, were used as controls. Strong unspecific labelling, which also could be suppressed with IgG from preimmune sera, was observed in a soil under a barn. Changes due to the permanent dryness and the lack of aeration are discussed as possible causes.