PARENT SESSION

PH04 Advances in Analysis and Measurements
Exhibit Hall
8:00 AM - Thursday

(PH007) Solid phase micro-extraction of pyrethroid, organophosphate and organochlorine pesticides in water and sediment.

You, J¹, Lydy, M¹, ¹ Southern Illinois University, Carbondale, IL, USA

ABSTRACT- Simultaneous determination of seven pyrethroid, one organophosphate and 20 organochlorine pesticides in water and sediment was achieved with headspace solid phase micro-extraction (HS-SPME) followed by gas chromatography - electron-capture detection. Without direct contact of the SPME fiber and the matrix, HS-SPME provided the advantages of low background contamination, long life expectancy of the fiber, and short equilibrium time. A 100m polydimethylsiloxane fiber was chosen for SPME extraction due to its high affinity to non-polar target pesticides. Other parameters affecting HS-SPME extraction efficiency from water were optimized, including extraction temperature, extraction time, sample and headspace volumes, salt and organic solvent amount, adsorption temperature, adsorption time and position of the fiber in the GC inlet. Extraction temperature was the most important factor affecting the recoveries of analytes, and the optimized temperature for pyrethroids was much higher than that for OCs and the OP. The method detection limits were in the ng/L level with a linearity range of 50-1000ng/L for OCs and 50-20000ng/L for pyrethroids, respectively. With the standard addition calibration, sediment samples were also assessed with the HS-SPME method. Sediment samples were heated in a 40mL vial at 90°C with continuous agitation, and the fiber was exposed to the headspace over the sediment slurry for 30min. Analytes were immediately desorbed by inserting the fiber into GC inlet at 260°C for 10min. Sediment samples aged for different periods of time were evaluated with this HS-SPME method, and the HS-SPME method was compared with an early established sonication - Florisil column chromatography cleanup method for the analysis of field-collected sediment collected from California.

Key words: pyrethroid, headspace solid phase micro-extraction, organochlorine pesticide, sediment