Use of Cobalt Thiocyanate for Thin-Layer Chromatographic Detection of Neonicotinoid Insecticide Imidacloprid

Abstract

Imidacloprid is a member of chloronicotinyl neonicotinoid compounds. It is the most important systemic insecticide and has a wide diversity of uses: in agriculture, on turfs, on pets, and for household pests. During the last decade, Forensic Science Laboratories of Maharashtra State, India, detected a large number of human poisoning cases with imidacloprid. Since a large number of biological samples were received for toxicological analysis, thin-layer chromatography (TLC) was the method of choice. This study reports that cobalt thiocyanate was found to be a selective and sensitive spray reagent for imidacloprid in routine analysis by TLC. Imidacloprid reacts with cobalt thiocyanate which gives intense blue-colored compound. The cobalt thiocyanate reagent does not react with the organochlorine insecticides, organophosphorus insecticides, and pyrethroids. Visceral constituents (amino acids, peptides, proteins, etc.) do not interfere.