Determination of the pesticides in fish
samples was carried out by the method of Goto
and Kato (1980) modified as follows. In brief, a
fish sample (c. 1 g) was homogenized twice with
each 30 ml of acetonitrile after addition of 3 g of
anhydrous Na,SO, and the organic layer was
filtered. The combined filtrate was rotaryvacuum
evaporated just to dryness at 40°C. The
residue was dissolved in 10 ml of hexane and
shaken twice with each 30ml of acetonitrile
saturated with hexane. The combined acetonitrile
layer was rotary-vacuum evaporated just
to dryness at 40°C. The residue was dissolved
with 5 ml of acetone and passed through a
column (a mixture of activated charcoal 0.2 g
and microcrystalline cellulose 2.0 g). Each pesticide
was eluted with 100 ml of acetone and
analyzed by FPD-GC after rotary-vacuum
evaporation to l-5 ml at 40°C. Average recoveries
(whole body of fish 1 g, n = 3) were 90% for
IBP, 96% for parathion and 95% for EPN at a