Optimization of Membrane-Protected Micro-solid-Phase Extraction Coupled with Dispersive Liquid-Liquid Microextraction for Determination of Organochlorine Pesticides in Soil Media

摘要

A novel and efficient method has been developed for the determination of organochlorine pesticides in soil using gas chromatography-electron capture detection. To achieve the optimum performance for simultaneous analysis of the selected analytes, the most important experimental parameters: extraction time, added water volume, salting-out effect, desorbing solvent type and volume, and desorption time were studied. The micro-solid-phase extraction sorbent consisted of 10 mg of multi-walled carbon nanotube packed within polypropylene envelope and immersed for 50 min inside the soil-water mixture (1.0 g of dried and sieved soil and 3.0 mL of water). After solvent desorption using 1.5 mL of methanol, the final extract was further processed through a dispersive liquid-liquid microextraction procedure to improve the method sensitivity. The limits of detection of the targeted analytes ranged between 0.11 and 1.07 ng g(-1) and the analytical responses were linear from 5 to 400 ng g(-1). The reproducibility of the method (as RSD) was also evaluated to be less than 14% (50 ng g(-1) level). The figures of merit of the entire procedure showed that the presented technique was capable of satisfactorily analyzing organochlorine pesticides in the environmental soil samples through an inexpensive and straightforward procedure.