Extraction and determination by gas chromatography of S,S,S-tri-n-butyl phosphorotrithioate (DEF) in fish and water

A simple, low-cost, fast method for the extraction and cleanup of DEF (S,S,S-tri-n-butyl phosphorotrithioate) from fish tissues and water samples was developed. The method combines extraction and cleanup in one step. The basis of the method is passing water samples or aqueous tissue homogenates containing DEF through a C-18 disposable cartridge. DEF is eluted from the cartridge by acetone or ethyl acetate. The eluates are analyzed by gas chromatography using a thermionic-specific detector. The method detects levels as low as 100 parts per trillion (ppt) in water samples; recovery efficiency from spiked fish tissues was greater than 95%. In addition, detectable levels of DEF were recovered from liver, brain, and muscle tissue of fish exposed to this compound. The method has a potential for use with other pesticides.