Development and application of vortex-assisted membrane extraction based on metal-organic framework mixed-matrix...

A vortex-assisted membrane extraction (VA-ME) method based on several metal-organic framework mixed-matrix membranes (MOF-MMMs) was firstly developed and applied for the analysis of four estrogens in human urine. The MOF-MMMs, with high MOF loading (∼67 wt%), were prepared using a facile approach by embedding the MOFs in a polyvinylidene difluoride matrix. The method was suitable for a wide variety of MOF materials, and the incorporated MOFs retained their unique properties. Being model analytes, the estrogens became adsorbed on the MOFs in the vortex-stirred sample solutions and were subsequently desorbed in methanol and analyzed using high-performance liquid chromatography with fluorescence detection. The performance and durability of MIL-53(Al)-MMM was particularly noteworthy and was therefore selected to extract estrone, 17β-estradiol, estriol, and ethinylestradiol from the urine of children and postmenopausal women. Various extraction conditions were optimized, and the analytical method showed good linearity in the range of 0.02-200 ng mL^-1, recoveries ranging from 80.4% to 102.7% (RSD≤11.4%), and low limits of detection (0.005-1 ng mL^-1). VA-ME is a simple, accurate, and cost-effective pretreatment method, and its advantages such as good adsorption performance, simple operation, and straightforward removal and separation from solution highlight its broad utility for aqueous sample pretreatment.