Development of competitive enzyme-linked immunosorbent assays (ELISAs) based on monoclonal antibodies for chloronicotinoid insecticides imidacloprid and acetamiprid Original Research Article

Enzyme-linked immunosorbent assays (ELISAs) based on monoclonal antibodies (MoAbs) for chloronicotinoid insecticides imidacloprid and acetamiprid were developed. The MoAbs for either imidacloprid or acetamiprid were obtained utilizing mice with 3-[5-(2-nitroiminoimidazolidin-1-ylmethyl)-2-pyridylthio]propionic acid or 3-[5-(N-(1-cyanoiminoethyl)-N-methylaminomethyl)-2-pyridylthio] propionic acid haptens conjugated to bovine serum albumin, respectively. Both MoAbs (33C3-1-1 for imidacloprid and 45E10-1-1 for acetamiprid) characterized by an indirect competitive ELISA showed high sensitivity and low cross-reaction to related compounds. Direct competitive ELISAs (DC-ELISAs) with 33C3-1-1 for imidacloprid or with 45E10-1-1 for acetamiprid were tested on spiked vegetable and fruit samples without clean-up procedures. The mean recovery of the either assay measured by DC-ELISA ranged from 80 to 120% for imidacloprid or from 80 to 100% for acetamiprid, respectively. Both recovery tests for imidacloprid and acetamiprid showed good performance by DC-ELISA at the permitted level (0.5 ppm for imidacloprid and 1 ppm for acetamiprid) in vegetable and fruit. The result demonstrates that these assays could be easier to handle and as well as lesser expensive than usual high-performance assays such as gas chromatography (GC), high performance liquid chromatography (HPLC) and GC-mass spectrometry (GC-MS).