Determination of Dephosphate-bromophenophos Excreted in Cow's Milk by Gas-Liquid Chromatography Using an Electron Capture Detector

Abstract

A method for the determination of dephosphate-bromophenophos (TBB) in cow's milk by gas-liquid chromatography using an electron capture detector is described. TBB was extracted with acetonitrile and re-extracted into ethyl acetate-n-hexane (2:1). The crude extract was purified by partition into n-hexane under alkaline and acidic conditions and was then converted into the trimethylsilyl derivative. This derivative was separated on an OV-1 column, exhibiting a single peak on the chromatogram without any interference. A calibration graph was constructed by plotting the peak height ratio of TBB to the internal standard against the amount of TBB, and satisfactory linearity was observed in the range of 25 to 350pg. TBB added to cow's milk specimens was recovered at the rate of 100.1±1.18%. The proposed method was applied to quantitation of TBB in cow's milk after oral administration of bromophenophos (12mg/kg). TBB in cow's milk reached a maximum level (0.12-0.18ppm) at 24-48hr and then disappeared within 84hr.