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Development and validation of a SPE-GC-MS method for the determination of pesticides in surface water

A method for analysis of 20 commonly used pesticides in surface water based on solid-phase extraction and gas chromatography-mass spectrometry was proposed. During method development the key parameters that can affect SPE extraction and determination such as selection of efficient SPE sorbent, pH of water sample, type and volume of elution solvent, breakthrough volume and matrix effects were investigated. The method was validated using spring water spiked with appropriate concentration of pesticides. The obtained correlation coefficients were in range 0.9972–1.000, limits of detection (LOD) were 0.001–0.5 µg L−1 and the limits of quantification (LOQ) were 0.005–1 µg L−1 depending on a pesticide. Much higher LOD (20 µg L−1) and LOQ (50 µg L−1) values were obtained for bentazone. The influence of matrix was assessed using real water samples spiked with appropriate concentration of pesticide standards solution. Both signal enhancement and suppression were observed, depending on a pesticide, therefore standard addition method was used for pesticides determination. The developed method was applied on real water samples taken in close vicinity of agricultural fields. Many of the targeted pesticides were found in the samples and the results are presented in this article.