Extraction and clean-up methods for the determination of amitraz total residues in beeswax by gas chromatography with electron capture detection

A comparative study on several extraction/clean-up procedures to determine total amitraz residues in beeswax is presented. The procedures are tested on samples spiked with amitraz, N-(2,4-dimethylphenyl)-Nʹ-methylformamidine (DPMF) and 2,4-dimethylaniline (DMA) at two concentration levels. The extraction with methanol followed by a partitioning with n-hexane seems to be the most adequate procedure in terms of recovery (about 80%) and precision (R.S.D. lower than 15%). The analytes in the extracts are determined by GC/ECD after their hydrolysis to DMA and subsequent formation of the heptafluoro-N-(2,4-dimethylbenzene)butanamide.