Application of empore disk extraction for trace analysis of spinosad and metabolites in leafy vegetables, peppers, and tomatoes by high-performance liquid chromatography with ultraviolet detection

Residue methods were developed for the quantitation of spinosad and metabolites in leafy vegetables, peppers, and tomatoes. The compounds were extracted with a solution of acetonitrile/water. The extract was purified and concentrated by C-18 Empore disk extraction, followed by silica and cyclohexyl solid-phase extraction. All five analytes in the purified extract were determined simultaneously by reversed-phase high-performance liquid chromatography with ultraviolet detection. For all analytes in six different commodities, the average recoveries ranged from 77 to 97% with standard deviations ranging from 2 to 7%. The Limits of quantitation and detection were 0.01 and 0.003 mu g/g, respectively, These results compare favorably with those obtained by replacing the Empore disk extraction with liquid-liquid partitioning in the method. Analysis of cabbages sprayed with [C-14]spinosyn A from a residue study indicated that the Empore disk extraction provided a cleaner final extract, Confirmation of analytes was performed by using liquid chromatography/mass spectrometry.