Cyano-functionalized ionic porous polymer: A novel adsorbent for effectively enriching trace estrogens in water and milk

Estrogens have been recognized as a class of endocrine disruptors. It is of utmost significance to develop a sensitive analytical method for the reliable determination of estrogen in environmental and food samples. Herein, a series of cyano-functionalized ionic porous organic polymers (CN-iPOPs) were successfully prepared for the first time using (1-imidazolyl)acetonitrile and biphenyl dichlorobenzene as building blocks via Friedel-Crafts alkylation reaction. The optimized CN-iPOPs (CN-iPOP3) displayed exceptional sorption capacity for estrogens, making it an advanced adsorbent for solid phase extraction (SPE) of estrogens. In combination, CN-iPOP3 based SPE with high performance liquid chromatography, a sensitive and reliable method was developed for deter-mination of four estrogens in lake water and milk samples. Under optimal conditions, good linear response was obtained to be 0.09-100.0 ng mL-1 for lake water and 0.90-1000.0 ng mL-1 for milk, with detection limits (S/N = 3) of 0.03-0.05 ng mL-1 and 0.30-0.70 ng mL-1 respectively. The method recoveries were in the range of 85.0%-119.0% with the relative standard deviations lower than 7.8%. The synergistic effect of electrostatic force, hydrogen bond, 7c-7c stacking interaction and hydrophobic interaction was proved to be the main adsorption mechanism. This research provides a promising approach to design iPOP-based adsorbents for effectively enriching or removing organic pollutants.