Solid-phase microextraction of pyrethroid pesticides from water at low andsub-ppt levels at different temperatures

Synthetic pyrethroids are increasingly being used for insect control on fie ld crops because of their advantageous environmental properties such as sho rt field life, broad spectrum of insecticide activity, and relatively low m ammalian toxicity. In the present work, experimental conditions were optimi zed for trace analysis of pyrethroids in water by using solid-phase microex traction followed by capillary gas chromatography. Effects of temperature, SPME-fiber diameter, and matrix were studied. SPME used off-line with a gas chromatograph electron-capture detection (GC-ECD) showed a linear response over a wide concentration range. Our results showed a strong temperature e ffect on pyrethroid extraction yield. The detection limit after 5 min of SP ME-fiber exposure to the samples changed from 1 ppb (at 30 degrees C) to 0. 1 ppt (at 90 degrees C), which is a 10000 increase in pyrethroid detection. The standard deviations of the analyte peak area ratios were typically in the range of 1-7% at 30 degrees C and of 3 to 15% at 90 degrees C. Best con ditions for pyrethroids analysis were achieved using high temperature solut ion and a 100 mu m polydimethylsiloxane fiber. No matrix (river water) infl uence was observed on detection of the investigated pyrethroids.