|Smith Jr, Sammie|
Submitted to: Bulletin of Environmental Contamination and Toxicology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2000
Publication Date: 6/1/2000
Interpretive Summary: New technologies in analytical chemistry have resulted from an increased demand for rapid extraction and cost-effective, multiple analysis of pesticide-associated samples. Unfortunately, newer analytical equipment is not always available; therefore, older methods using traditional equipment must be re-evaluated. This research reports the development of a rapid and sensitive method using standard chemistry equipment for extraction of a common herbicide and a pyrethroid insectide in sediment and aquatic plants. The method requires lower solvent volumes and reduced sample weights relative to the traditional methods. This research also demonstrated the need for extraction within 24 hours of natural water samples containing pesticide residues.
Technical Abstract: A rapid and sensitive method was developed for the simultaneous extraction (via sonication) and analysis (via gas chromatography) of the triazine herbicide atrazine (2-chloro-4-ethylamino-6-isopropylamino- 1,3,5-triazine) and the synthetic pyrethroid insecticide lambda- cyhalothrin [RS-alpha-cyano-3-phenoxybenzyl 3-(2-chloro-3,3,3- trifluoropropenyl)-2,2,-dimethylcyclopropanecarboxylate] in sediment and aquatic macrophytes. The method requires lower solvent volumes and reduced sample weights relative to the traditional EPA sonication method and Soxhlet methods. In addition to method development, a storage stability test was performed to determine acceptable storage times for natural water samples containing pesticide residues. Natural water samples were fortified with atrazine, l-cyhalothrin, and the chloroacetamide herbicide metolachlor [2-chloro-6'-ethyl-N-(2-methoxy-1- methylethyl)acet-o-toluidide]. These three pesticides represent three of the major classes of pesticides used extensively in row crop production in the area of the lower Mississippi River Basin known as the Mississippi Delta. Results from native sediment and plant samples sonicated using three different solvents indicate that ethyl acetate was the most effective extraction solvent. Results from comparison tests with traditional Soxhlet methods show that the present sonication method, which requires considerably less organic solvent, is as effective as Soxhlet extraction. Results from the storage stability tests with natural water samples containing pesticide residues demonstrated the need for extraction within 24 hours of collection.