Abstract
The analytical procedure based on stir‑bar sorptive extraction technique, for the determination of selected pesticide residues (diazinon, malathion, cyprodinyl, penconazole, fludioxonyl, pyriproxyfen, boscalid, pyraclostrobin) is described. Analysis was performed using the commercial TwisterTM stir bar for sorptive extraction. It consists of a 2.0‑cm‑long glass‑encapsulated magnetic stir bar externally coated with PDMS. The extracts were off‑line analyzed using fast GC‑MS in SIM mode. Optimized conditions were established as follows concerning extraction time, stirring speed, aqueous medium characteristics (ionic strength and polarity) respectively: 120 min (700 rpm), addition of 4 g of sodium chloride, no addition of methanol as organic modifier, and 30 min ultrasonic desorption in acetonitrile. Recoveries ranged from 38 % to 58 % (RSD < 15 %, n = 6). Validated limits of quantification in matrix were between 1.6 ngL−1 and 548.8 ngL−1, depending on the compound.
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