Determination of organochlorine pesticide residues in river sediments by soxhlet extraction with hexane-acetone

Soxhlet extraction with hexane + acetone (1 + 1 by volume) was used for the extraction of organochlorine pesticide residues from river sediments, followed by Florisil column chromatography clean‐up and determination by gas chromatography with an electron‐capture detector. Average recoveries exceeding 90 % were obtained using this technique. Organochlorine pesticide residue levels in sediment samples from two major rivers flowing through predominantly rice‐growing areas were determined by this method. Relatively high residue levels of organochlorine pesticides such as HCH, heptachlor and endosulfan were found in the sediments.