Determination of spinosad and its metabolites in meat, milk, cream, and eggs by high-performance liquid chromatography with ultraviolet detection

Spinosad is a naturally derived insect-control agent for use on cotton and a variety of other crops. A method is described for the determination of spinosad and its major metabolites in beef and poultry meat, milk, cream, and eggs. The method determines residues of the active ingredients (spinosyns A and D) and two metabolites (spinosyn B and N-demethylspinosyn D). For chicken fat, the method has a limit of quantitation (LOQ) of 0.02 mu g/g and a limit of detection (LOD) of 0.006 mu g/g. For all other chicken tissues, beef tissues, milk, cream, and eggs, the method has an LOQ of 0.01 mu g/g and an LOD of 0.003 mu g/g. The analytes are extracted from the various sample types using appropriate solvents, and the extracts are purified by liquid-liquid partitioning and solid-phase extraction. All four analytes are determined simultaneously in the purified extracts by reversed-phase highperformance liquid chromatography with ultraviolet detection at 250 nm.