Determination of fluvalinate residues in beeswax by gas chromatography with electron-capture detection.

A simple, rapid, and accurate method is described for the determination of residual fluvalinate in beeswax. The procedure consists of partitioning on a disposable column of diatomaceous earth (Extrelut), followed by chromatographic cleanup on a Florisil cartridge. The final extract is analyzed by capillary gas chromatography with electron-capture detection (GC-ECD). Briefly, wax samples were dissolved in n-hexane, and the solutions were sonicated and transferred to Extrelut columns. The fluvalinate was extracted with acetonitrile, and a portion of the extract was cleaned up on a Florisil cartridge. The fluvalinate was eluted with diethyl ether-n-hexane (1 + 1) and directly determined by GC-ECD. Recoveries from wax samples spiked at 5 fortification levels (100-1500 microg/kg) ranged from 77.4 to 87.3%, with coefficients of variation of 5.12-8.31%. The overall recovery of the method was 81.4 +/- 3.2%, and the limit of determination was 100 microg/kg.