Submitted to: Analytica Chimica Acta
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/4/2003
Publication Date: 1/31/2004
Citation: Kim, H., Shelver, W.L., Li, Q.X. 2004. Monoclonal antibody-based enzyme-linked immunosorbent assay for the insecticide imidacloprid. Analytica Chimica ACTA 509:111-118. Interpretive Summary: Imidacloprid (a neonicotinoid) is rapidly replacing the traditional pesticide classes such as pyrethroid, organophosphate, and carbamate because of its low acute toxicity to mammals, and noncumulative long-term toxicity. An immortal antibody secretion cell line that recognize imidacloprid has been generated. This antibody was utilized to develop an enzyme linked immunoassay toward imidacloprid. The antibody is very sensitive and has a minimal detection level of 100 parts per trillion. With the middle inhibition concentration is at 800 parts per trillion, making this antibody the most sensitive monoclonal antibody known today. Solvent effect was investigated, and it was found that the antibody was very rugged, can tolerate up tp 15% of acetone and 20% of methanol. With it's sensitivity and tolerance toward solvents, this rapid immunoassay has a great potential to develop into a field portable, high throughput analytical method to detect imidacloprid.
Technical Abstract: An enzyme-linked immunosorbent assay (ELISA) was developed for the neonicotinoid insecticide imidacloprid, 1-[(6-chloro-3-pyridinyl)methyl]-N-nitro-2-imidazolidinimine based on monoclonal antibody (MAb). Three MAbs were raised from mice immunized with the hapten II-OVA conjugate. The dissociation constants (Kd), and association and dissociation rate constants (Kon, Koff) for binding of five neonicotinoids and one metabolite to MAb were studied with kinetic exclusion immunoassay (KinExA). KinExA revealed that acetamiprid and clothianidin have similar binding affinities to MAb, but bind much less than imidacloprid. Other compounds showed no affinity to MAb. Physicochemical effects on assay performance were also estimated. MAb was tolerant up to 15% of acetone and 20% of MeOH. Other parameters showed no significant effects on assay sensitivity in the tested range. Under optimized conditions, the half-maximal inhibition concentration (I50) and the limit of detection were approximately 0.8 and 0.1 micrograms/L, respectively, making it the most sensitive MAb toward imidacloprid known today. The ELISA analysis of water samples fortified with imidacloprid showed a good correlation between the fortified and determined concentration.