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Gas ch romatog ra phy SPME Pesticides Plants and soil SummaryPesticides volatilised from plants and soil were determined by headspace SPME and gas chromatography with electron-capture and mass spectrometric detection. SPME analyses were carried out with polydimethylsiloxane (PDMS) and polyacrylate (PA) fibres. A mixture of endosulfan, chlorpyrifos, hndane and pendimethalin was used in these assays. Fortified soil and plant samples were maintained at 30 ~ for 2 h and 1 h, respectively, before SPME sampling. Pesticides were extracted by SPME by inserting the sheathed fibre through the cap and exposing it to the headspace for 1 h.GC-ECD analysis was performed after thermal desorption of pesticides from the fibre for 5 minutes. Pesticide identily was confirmed by mass spectrometry operating in the electron impact mode (El). The SPME fibres assayed gave good results, the response obtained with the PDMS fibre being somewhat belter in the concentration range studied. Detection limits for the compounds studied varied from 1 to 8 ng L 1.