Solid-phase extraction of carbaryl and malathion from pond and well water

An analytical method was developed using C8 solid-phase extraction columns to extract carbaryl and malathion from well and pond water. Mean percent recovery over a concentration range of 1 μg/L to 10,000 μg/L was consistently between 80 and 100. Well-water samples fortified with carbaryl and malathion were solid-phase extracted, and analytes were stored on solid-phase extraction columns at —4°C for 30 d without significant decomposition. The method was field-tested by collecting pond water before and after an application of malathion. It provided significantly higher recovery of malathion than a liquid-liquid extraction procedure.