Supercritical fluid extraction of chlorpyrifos and 3,5,6-trichloro-2-pyridinol from garden compost

A method was developed for the simultaneous supercritical carbon dioxide ex traction of chlorpyrifos and its primary degradate, 3,5,6-trichloro-2-pyrid inol (TCP), from garden compost. In situ derivatization with N,O-bis( trime thylsilyl)trifluoracetamide was necessary for extraction of TCP. Recoveries for TCP and chlorpyrifos were quantitative for spiked compost samples. Sod ium chloride was used as the packing material in extractions with in situ d erivatization. Optimum results were obtained for air-dried samples containi ng 4-7% moisture. No sample cleanup was required prior to analysis by CC-fl ame ionization detection. The effects of compost moisture content and agein g were investigated for chlorpyrifos recovery. No significantly negative ef fect on recovery for up to 20% (w/w) moisture for chlorpyrifos was observed . Effects of ageing showed a decrease in extraction efficiency over time wi th 52% recovery after 10 days. (C) 1999 Elsevier Science B.V. All rights re served.