Preparation of carboxylatocalix[4]arene functionalized magnetic polyionic liquid hybrid material for the pre-concentration of phthalate esters.

In this work, we designed a novel hybrid material based on the polymerization of an ionic liquid on a magnetic core and further functionalized with carboxylatocalix[4]arene. Scanning electron microscope, transmission electron microscope, Fourier transform infrared spectroscopy, thermal gravimetric-derivative thermogravimetric analysis, energy dispersive X-ray spectroscopy, X-ray diffractometer, and vibrating sample magnetometer were utilized to examine the physicochemical properties of the hybrid material obtained. The material was used as the adsorbent for magnetic solid-phase extraction of phthalate esters. To obtain the maximum pre-concentration efficiency, a series of parameters influencing the extraction efficiency, including sample pH, adsorbent amount, adsorption time, eluent type as well as salt addition, was examined systematically. Under the optimum conditions, a fast and feasible pre-concentration protocol for phthalate esters was established with satisfactory enrichment factors between 158.7 and 191.3. The limits of detection from high-performance liquid chromatographic analysis for the target analytes were in the range of 0.02-0.31 ng mL. The wide linear ranges varying from 0.1 to 100 ng mL were achieved with correlation coefficients greater than 0.9977. To evaluate the feasibility of this method, it was successfully applied to analyse phthalate esters in multiple kinds of real samples including tap water, lake water, drinks, tonic lotions, and human serum samples. The results obtained demonstrated that the synthesized magnetic material had potential as a candidate in the pre-concentration field for phthalate esters due to the special properties stemming from its structure and components.