Abstract
Organochlorine insecticides were extracted from water using a C-18 solid phase extraction cartridge. The concentrated pesticide residues were spotted directly for silica gel TLC separation, followed by detection with ammoniacal AgNO3 solution and quantification by densitometric scanning. When removal of interfering constituents was required, the extract was chromatographed on a water-deactivated silica gel column. Recoveries of methoxychlor and p, p′-DDT were greater than 90% at fortification concentrations of 2.5 and 0.25 ppb for waters not requiring silica gel cleanup and greater than 85% when this step was included.

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