Microfunnel-filter-based emulsification microextraction followed by gas chromatography for simple determination of organophosphorus pesticides in environmental water samples.

A simple and fast method named microfunnel-filter-based emulsification microextraction is introduced for an efficient determination of some organophosphorus pesticides including diazinon, malathion, and chlorpyrifos in the environmental samples including the river, sea, and well water. This method is based upon the dispersion of a low-toxicity organic solvent (dihexyl ether), as the extractant, in a high volume of an aqueous sample solution (45 mL). It is implemented without a centrifugation step, and using a syringe filter and a micro-funnel, the phase separation and transfer of the enriched analytes to the gas chromatograph are simply achieved. By filtration of the extractant phase, a suitable sample clean-up is obtained, and the total extraction time is just a few minutes. The factors influencing the extraction efficiency are optimized, and under the optimal conditions, the proposed method provides a good linearity (in the range of 15-1500 ng/mL (R2  > 0.996). A high enrichment factor is obtained (in the range of 306-342), and the method provides low limits of detection and quantification (in the ranges of 4-8 and 15-25 ng/mL, respectively).