|MEETING SITE HOME SCHEDULE AUTHOR INDEX SUBJECT INDEX PROGRAM # INDEX ITINERARY SIGNUP|
MP5 Agrochemicals and Pesticides
(BON-1117-749339) Evaluation of Kd for Synthetic Pyrethroids Using Solid Phase Microextraction and Solvent Extraction.
Bondarenko, S1, Qin, S1, Gan, J1, 1 UC Riverside, Riverside, CA, USA
ABSTRACT- Sorption on sediment regulates the fate and bioavailability of contaminants in the aquatic environment. A common way to measure adsorption capacity of organic compounds in soil or sediment is to use the batch equilibration-solvent extraction method in which the solid and aqueous phases are separated by centrifugation and the aqueous phase concentration Cw is determined after exhaustive solvent extraction. However, this method may give artificially depressed Kd for strongly adsorbing compounds such as pyrethroids, as small colloidal particles and dissolved organic matter are not eliminated from the aqueous phase and may increase Cw. Solid phase microextraction (SPME) selectively detects the freely dissolved concentration and thus may be used to improve Kd measurement. Kd values for eight pyrethroid insecticides were determined using both solvent extraction (LLE) and SPME to measure Cw. Kd obtained with SPME was 2-100 times greater than that with the solvent extraction method. For instance, Kd values for cypermethrin measured by SPME and LLE were 1.16×104 L/kg and 0.85×103 L/kg, respectively. The difference was more significant for sediments with higher organic matter content. Kd measured with SPME is expected to be useful for predicting the bioavailability or toxicity of sediment-borne pyrethroids, as it correlates with the free or bioavailable concentration.
Key words: adsorption, synthetic pyrethroids, SPME
Internet Services provided by|
Allen Press, Inc. | 810 E. 10th St. | Lawrence, Kansas 66044 USA
e-mail email@example.com | Web www.allenpress.com
All content is Copyright © 2005 SETAC