PESTICIDE STABILITY STUDIES UPON STORAGE IN A GRAPHITIZED CARBON-BLACK EXTRACTION CARTRIDGE

The stability of 34 selected pesticides extracted from water onto the graphitized carbon black (GCB) surface was evaluated under various storage conditions. The best results were obtained by first minimizing the water content into the GCB extraction cartridge by a suitable methanol washing and then freezing the cartridge. Under these conditions and over a storage period of 3 weeks, the stability of pesticides extracted from four river water samples onto the GCB surface was assessed and compared with that in water at 4 degrees C with and without an inhibitor of biological degradation, such as HgCl2. Results indicated that storage on the GCB-material was a far better preservation procedure than storage in water at 4 degrees C. Several of the pesticides considered were completely degraded when stored in water in the presence of HgCl2.