A β-cyclodextrin sorbent based on hierarchical mesoporous silica for the determination of endocrine-disrupting chemicals in urine samples

Efficient recovery of bisphenol A from aqueous solution using K2CO3 activated carbon derived from starch-based polyurethane

Endocrine-disrupting compounds (EDCs) are increasingly polluting water, making it of practical value to develop novel desirable adsorbents for removing these pollutants from wastewater. Here, a simple cross-linking strategy combined with gentle chemical activation was demonstrated to prepare starch polyurethane-activated carbon (STPU-AC) for adsorbing BPA in water. The adsorbents were characterized by various techniques such as FTIR, XPS, Raman, BET, SEM, and zeta potential, and their adsorption properties were investigated comprehensively. Results show that STPU-AC possesses a large surface area (1862.55 m²·g^-1) and an abundance of functional groups, which exhibited superior adsorption capacity for BPA (543.4 mg·g^-1) and favorable regenerative abilities. The adsorption of BPA by STPU-AC follows a pseudo-second-order kinetic model and a Freundlich isotherm model. The effect of aqueous solution chemistry (pH and ionic strength) and the presence of other contaminants (phenol, heavy metals, and dyes) on BPA adsorption was also analyzed. Moreover, theoretical studies further demonstrate that hydroxyl oxygen and pyrrole nitrogen are the primary adsorption sites. We found that the efficient recovery of BPA was associated with pore filling, hydrogen-bonding interaction, hydrophobic effects, and π-π stacking. These findings demonstrate the promising practical application of STPU-AC and provide a basis for the rational design of starch-derived porous carbon.

Room temperature fabrication of magnetic covalent organic frameworks for efficient enrichment of parabens in water

A novel 4 + 2 covalent magnetic organic framework (COF) with core-shell structure was synthesized for the first time with N, N, N', N'-Tetrakis (4-aminophenyl)-1, 4- benzenediamine (TPDA) and 2, 6-Pyridinedicarboxaldehyde (PCBA) at room temperature. The synthesized magnetic TPDA-PCBA-COF has a large specific surface area and superparamagnetism, which makes it an ideal sorbent for trace analytes enrichment. To this end, we combined it with magnetic solid phase extraction (MSPE) to enrich trace parabens in environmental water. The parameters affecting the enrichment efficiency of magnetic solid phase extraction, such as the amount of Fe₃O₄@TPDA-PCBA-COF, extraction time, pH of samples, salt concentration, desorption solvent volume and desorption time, were optimized. A simple method for extraction and determination of parabens in water samples by MSPE combined with high performance liquid chromatography (HPLC) was established under optimized conditions. The validation results revealed that the linear ranges were at 1.0-5.0 × 10² ng mL^-1 with R value between 0.9915 and 0.9999, the spiked recoveries were in the range of 82.8% to 99.9% and RSDs were lower than 10%. The method was further applied to the determination of parabens in water samples, with recoveries in the range of 82.2% to 110.0% and RSDs ≤ 7.7%. These results suggest that the magnetic TPDA-PCBA-COF could be used as a promising adsorbent for efficient extraction and quantitation of parabens in environmental water samples.

Improved method for the determination of endocrine-disrupting chemicals in urine of school-age children using microliquid-liquid extraction and UHPLC-MS/MS

The presence of endocrine-disrupting chemicals in our daily life is increasing every day and, by extension, human exposure and the consequences thereof. Among these substances are bisphenols and parabens. Urine is used to analyze the exposure. The determination of 12 bisphenol homologues and 6 parabens is proposed. A procedure based on a method previously developed by our research group in 2014 is improved. The extraction yield is higher, because the new protocol is 5 times more efficient. Also, a comparison between calibration with pure standards and matrix calibration, to calculate the matrix effect, was also made. A high grade of matrix effect for all analytes was observed. In terms of validation, the limits of detection (LOD) were between 0.03 and 0.3 ng mL^-1 and limits of quantification (LOQ) 0.1 to 1.0 ng mL^-1, respectively, and the recovery is higher than 86.4% and lower than 113.6%, with a RSD lower than 13.5% in all cases. A methodology for accurate and sensitive quantification of bisphenol homologues together with parabens in human urine using UHPLC-MS/MS was developed. The method was successfully applied to 30 urine samples from children.