Submitted to: Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/19/1996
Publication Date: N/A
Interpretive Summary: The use of solid phase extraction (SPE) techniques for determination of pesticides in surface and ground water has reduced the amount of potentially hazardous organic solvents compared to traditional liquid- liquid extraction (LLE) procedures. Additionally, SPE techniques are usually faster and less labor intensive than LLE techniques. Summarized briefly, SPE procedures include conditioning the disk with solvent, slow vacuum filtration of the sample through the disk, and elution from the disk. Results from these studies demonstrate that immersion of SPE disks directly into the sampling flasks, followed by decanting the water, and elution of the pesticide in the sample flask achieved adequate quantitative recoveries of the tested herbicides. While this approach continues the trend of reducing organic solvent usage and simplifying the procedural steps in SPE, individuals considering using this approach must recognize the lower analyte recoveries (approximately 12% less) as compared to vacuu filtration, and weigh that compromise with the benefits of simplicity and labor and costs reduction achieved. This technique has potential for in- field extraction of some pesticides which may be a significant advantage in some studies and mobile laboratories.
Technical Abstract: Pressures to reduce hazardous solvent use in traditional procedures for pesticide extractions from water have increased the use of solid phase extraction (SPE) technology. We have expanded the use of SPE disks beyond the procedural techniques previously used. By placing the SPE disks directly into the water in the sample collection bottle and allowing sorption through diffusion, we bypass the laboratory extraction process an reduce costs by eliminating the need for expensive vacuum filtering glassware. We determined atrazine (6-chloro-N-ethyl-N'-(1-methylethyl)-1, 3,5-triazine-2,4-diamine), acetochlor (2-chloro-N-(ethoxymethyl)-N-(2- ethyl-6-methylphenyl)acetamide), and alachlor (2-chloro-N-(2,6- diethylphenyl)-N-(methoxymethyl)acetamide) sorption from water as a function of contact time, degree of mixing, and disk size. Results are comparable to sample recovery achieved with traditional vacuum filtering extraction. This research suggests a simpler approach for pesticide extraction from water samples compared to current methods, and may allow for in-field extraction of some pesticides.