Each concentration of the pesticides in water
samples was determined by the following procedure.
A measured volume (100 ml) of water
was shaken with 50 ml of hexane after addition
of 10 g of NaCl. The organic layer was injected
into a gas chromatograph equipped with a flame
photometric detector (FPD-GC) after rotaryvacuum
evaporation to 5 ml. Average recoveries
(n = 3) were 92% for IBP, 94% for parathion
and 93% for EPN at a spiked level of 5 pg ll’.