Development of a compound-specific ELISA for flufenoxuron and an improved class-specific assay for benzoylphenylurea insect growth regulators

This study describes immunochemical approaches for the compound-specific de tection of flufenoxuron and class-specific detection of benzoylphenylurea ( BPU) insecticides. With the aim of developing a highly specific immunoassay for flufenoxuron, a hapten was synthesized by introducing a spacer arm at the 2,6-difluoro substituent aromatic ring of a flufenoxuron derivative. An IC50 value of 2.4 ppb was obtained for flufenoxuron, with detection of the other four BPUs being more than 4000-fold less sensitive. For the developm ent of class-specific ELISA for five BPUs, a new approach was used for the hapten preparation in which a butanoic acid linkage was introduced into the 3,5-dichloro-substitued aniline ring of chlorfluazuron analogue. Although the resultant ELISA still exhibited slightly differing cross-reactions for these five BPUs, this method had broader specificity than the previously re ported polyclonal antibody-based ELISA. Spike and recovery studies for five BPUs in soil and water indicated that both the compound- and class-specifi c ELISAs were able to quantitatively detect BPU residues in soil and water. This study also provided additional insights into the influence of the imm unizing hapten structure on the specificities of the antibodies obtained.