Evaluation of the toxicity of imidacloprid in wild birds. A new high performance thin layer chromatography (HPTLC) method for the analysis of liver and crop samples in suspected poisoning cases

Several accidents were reported in France, in domestic and wild animals, involving the potential ingestion of imidacloprid-coated seeds. Imidacloprid is a new insecticide which acts as a nicotinic blocker. Since there was very limited published information regarding this compound, its toxicity to wild birds, and potential routine analytical techniques, this study was designed to set up and validate a method for the detection and quantification of imidacloprid and its primary metabolite, 6-chloronicotinic acid, in tissues and organs of affected animals. A high performance thin layer chromatography (HPTLC) technique was developed to quantify both compounds. The method is repeatable, reproducible, and sensitive enough to investigate potential poisoning cases (limits of quantification between 0.25 and 0.5 mu g/g). The technique was also applied successfully to birds found dead after a known exposure to the compound and indicates that imidacloprid accounts for the majority of the toxic residues detected in the liver of affected pigeons.