A novel approach using solid phase extraction disks for extraction of pesticides from water

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. Pesticides are sorbed onto preconditioned SPE disks placed directly into the water in the sample collection bottle and then eluted off the disks by solvents in the same bottle, bypassing the laboratory extraction process and reducing 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), [2-ethyl-6-methylphenyl]acetamide), and alachlor (2-chloro-N-[2,6-diethylphenyl]-N-[methylmethyl]acetamide) recovery from water as a function of contact time, degree of mixing, and disk size. Shaking 47-mm C8 extraction disks in 500 mL water for 20 h, follow ed by elution with ethyl acetate in the same sample collection bottle, resulted in >70% recovery of the three herbicides (1 mu g L(-1)) compared to >90% recovery for atrazine achieved with traditional vacuum-filtering er;traction. 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.