Tetrafluoroterephthalonitrile-crosslinked β-cyclodextrin polymer as a binding agent of diffusive gradients in thin-films for sampling endocrine disrupting chemicals in water

beta-Cyclodextrin (beta-CD) is an inexpensive and reproducible material derived from corn starch. It is possible that tetrafluomterephthalonitrile-crosslinked beta-cyclodextrin polymer (TEN-CD), a cheap but efficient adsorbent, could be a suitable binding agent for use in the passive sampling technique, diffusive gradients in thin-films (DGT). Herein, the TFN-CD binding gel was prepared and then evaluated as the binding phase of DGT to sample six endocrine disrupting chemicals (EDCs) in water. The TFN-CD dispersed uniformly in the binding gel due to its hydrophilicity. The quantitative recoveries (99.3%-106%) of EDCs from the TFN-CD binding gel could be conveniently achieved by ultrasonic extraction using 5 mL methanol for 10 min. Compared with the excellent HLB (hydrophilic-lipophilic-balanced resin) binding gel, the TFN-CD binding gel had comparable or even faster adsorption kinetics, although the equilibrium adsorption capacity was slightly lower. The effective adsorption capacities of TFN-CD-based DGT (TFN-CD-DGT) were roughly estimated to enable a 7-days deployment in EDC solution of 25.7-30.0 mu g L-1. Studies of influencing factors showed that the ionic strength (0-0.5 M), pH (3.73-9.13), dissolved organic matter (0-20 mg L-1) and long-term storage (204 days) had negligible influence on the performance of TFN-CD-DGT. Finally, the TFN-CD-DGT was successfully used to record sudden increases in bulk concentrations during simulated discharge events in pond water. These results demonstrate that TFN-CD is a suitable binding agent for sampling of EDCs, and the low cost of TFN-CD could be conducive to the application of DGT in large-scale sampling.