Application of solid-phase microextraction in the monitoring of priority pesticides in the Kalamas River (N.W. Greece)

A solid-phase microextraction (SPME) method was applied to an extended monitoring survey of priority pesticides for the European Union for a period of 12 months in water of the Kalamas River (Epirus region of northwestern Greece) in order to determine their concentrations and seasonal variations. Polydimethylsiloxane-coated fiber (100 μm) was used. The samples were screened using gas chromatography with flame thermionic detection. Detection was confirmed by gas chromatography–mass spectroscopy. The most frequently detected pesticides were some of the more commonly used herbicides, such as S-ethyl-N,N-di-n-propylthiol carbamate (EPTC), trifluralin, atrazine, deethylatrazine, terbuthylazine and alachlor, and insecticides, such as carbofuran, diazinon, disulfoton, parathion methyl, parathion ethyl, fenthion and ethion. Concentrations of individual compounds ranged from 0.020 to 0.3 μg/L. Greater pesticide concentrations occurred during the seasons of application. A comparison with a well-established solid-phase extraction (C18 disks) procedure was performed for samples of high-season application (May–September) in order to confirm the effectiveness of the SPME technique. The results demonstrate the suitability of the SPME method for routine screening multiresidue analysis in natural waters.