A rapid, low-cost, and simple method is proposed based on a miniaturized solid-phase extraction named microextraction in packed syringe coupled with gas chromatography and mass spectrometry for the preconcentration and determination of some organophosphorous pesticides including diazinon, ethion, and malathion. For the first time, natural nanoperlite is used as a safe sorbent. Based on this technique, the analytes are adsorbed on the solid phase and then eluted by a desorbing solvent. The influence of some important parameters such as the solution pH, type, and volume of the organic desorption solvent on the microextraction efficiency of the selected pesticide technique is investigated. The proposed method showed a good linearity in the range of 1.0-35.0 μg/L for ethion and 0.4-30.0 μg/L for both diazinon and malathion. The limits of detection in the range of 0.1-0.38 μg/L were obtained using the selected ion-monitoring mode of the mass spectrometer. The reproducibility of the method was found to be in the range of 2.8-8.9% for the studied pesticides. To evaluate the matrix effect, the developed method is also applied to the preconcentration and determination of the selected pesticides in real water samples.
Keywords: gas chromatography; microextraction; nanoperlite; organophosphorus pesticides.
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