Determination of residues of deltamethrin in milk and butter.

A method is described for the determination of deltamethrin, particularly in mild and dairy products. Residues and fat were co-extracted with acetone and light petroleum, partitioned with acetonitrile-methylene chloride and centrifuged (-10 degrees C). The extract was purified by gel permeation chromatography. A Florisil clean-up method was tested but did not seem effective enough. Analysis was performed by gas-liquid chromatography with a 63Ni electron-capture detector on 3% SE-30 using a short column (40 cm). Confirmation was effected by gas chromatography-mass spectrometry with an SE-30 capillary column (10 m). Recoveries from fortified samples ranged from 72 to 88% for milk spiked with 0.06 ppm and butter spiked with 2 ppm and was 94% for milk spiked with 0.016 ppm of deltamethrin.