Preconcentration of organophosphorus pesticides from aqueous solutions with graphitized carbon black column.

A procedure has been developed for determining organophosphorus pesticides at μg/1 levels in aqueous solutions after preconcentration on graphitized carbon black (GCB). Six organophosphorus pesticides (methyl demeton, diazinon, methyl parathion, MEP, parathion, and EPN) were adsorbed on a GCB column from 500 ml of aqueous solution. The pesticides were then eluted with acetone and dichloromethane (5 ml of total volume). Without further purification and concentration, the effluent was analyzed by gas chromatography using a flame photometric detector (FPD). The recoveries (n=9) and the relative standard deviations at 4 μg/1 each of pesticides were in the ranges of 94 to 97 % and 2.2 to 3.9 %, respectively. Effects of many foreign substances were examined. The proposed procedure was applied to tap water and wastewater.