1990 Volume 15 Issue 2 Pages 205-209
A simple and efficient cleanup procedure for gas chromatographic determination of pesticide residues was examined by the chromatographic technique using a charcoal-Florisil minicolumn. Samples were extracted with methanol, partitioned into toluene, and cleaned up with the minicolumn prior to the determination of pesticide residues by a GC-ECD and a GC-FTD. Recovery data were obtained by fortifying 15 crops with 25 pesticides at the tolerance level of each pesticide. Recoveries of 23 pesticides were higher than 90%, but those of dimethoate and oxadixyl were poor, which seemed to be due to their high polarities and an inefficient partitioning into toluene and a strong adsorption with Florisil in the elution system. Detection limits by the method were 0.01-0.02ppm for organophosphorus pesticides, 0.05ppm for carbamate and synthetic pyrethroid pesticides and 0.005ppm for organochlorine pesticides. The method was simple and applicable to the routine surveillance of various pesticide residues in many kinds of crops.
