Poly（vinylidene fluoride） membrane based thin film microextraction for enrichment of benzoylurea insecticides from water samples followed by their determination with HPLC

Thin-film microextraction（TFME）,a new geometry for solid-phase microextraction,has become an attractive sample-preparation technique.Compared to other microextraction approaches,the sensitivity of this technique was enhanced without sacrificing the sampling time due to the high surface area-tovolume ratio together with the increase of extraction-phase volume.In this paper,a new TFME method based on poly（vinylidene fluoride） membrane was developed for the extraction of benzoylurea insecticides（diflubenzuron,triflumuron,hexaflumuron and teflubenzuron） from water samples followed by their determination with high performance liquid chromatography-diode array detection.Under the optimal conditions,good linearity was observed over the concentration range of 0.5-100.0 ng/mL with correlation coefficient greater than 0.9994.The limits of detection（S/N = 3） of the method for the target analytes were 0.1 ng/mL.Mean recoveries ranged from 87.7% to 103.9% with relative standard deviations lower than 6.5%.The results indicated that the developed TFME method is simple,efficient,and cost effective.