Preparation of deep eutectic solvent modified magnetic graphene oxide/metal organic framework nanocomposites for the extraction of three estrogens in cosmetics.

A novel magnetic dispersive solid phase extraction (MDSPE) procedure based on the deep eutectic solvent (DES) modified magnetic graphene oxide/metal organic frameworks nanocomposites (MGO@ZIF-8@DES) was established and used for the efficient enrichment of estradiol, estrone, and diethylstilbestrol in cosmetics (toner, lotion, and cream) for the first time. Then, the three estrogens were separated and determined by UHPLC-UV analysis method. In order to study the features and morphology of the synthesized adsorbents, various techniques such as FT-IR, SEM, and VSM measurements were executed. The MGO@ZIF-8@DES nanocomposites combine the advantages of high adsorption capacity, adequate stability in aqueous solution, and convenient separation from the sample solution. To achieve high extraction recoveries, the Box-Behnken design and single factor experiment were applied in the experimental design. Under the optimum conditions, the method detection limits for three estrogens were 20-30 ng g-1. This approach showed a good correlation coefficient (r more than 0.9998) and reasonable linearity in the range 70-10000 ng g-1. The relative standard deviations for intra-day and inter-day were beneath 7.5% and 8.9%, respectively. The developed MDSPE-UHPLC-UV method was successfully used to determine  three estrogens in cosmetics, and acceptable recoveries in the intervals of 83.5-95.9% were obtained. Finally, three estrogens were not detected in some cosmetic samples. In addition, the Complex GAPI tool was used to evaluate the greenness of the developed pretreatment method. The developed MDSPE-UHPLC-UV method is sensitive, accurate, rapid, and eco-friendly, which provides a promising strategy for determining hormones in different complex samples.

Diethylstilbestrol Modifies the Structure of Model Membranes and Is Localized Close to the First Carbons of the Fatty Acyl Chains.

The synthetic estrogen diethylstilbestrol (DES) is used to treat metastatic carcinomas and prostate cancer. We studied its interaction with membranes and its localization to understand its mechanism of action and side-effects. We used differential scanning calorimetry (DSC) showing that DES fluidized the membrane and has poor solubility in DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) in the fluid state. Using small-angle X-ray diffraction (SAXD), it was observed that DES increased the thickness of the water layer between phospholipid membranes, indicating effects on the membrane surface. DSC, X-ray diffraction, and 31P-NMR spectroscopy were used to study the effect of DES on the Lα-to-HII phase transition, and it was observed that negative curvature of the membrane is promoted by DES, and this effect may be significant to understand its action on membrane enzymes. Using the 1H-NOESY-NMR-MAS technique, cross-relaxation rates for different protons of DES with POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) protons were calculated, suggesting that the most likely location of DES in the membrane is with the main axis parallel to the surface and close to the first carbons of the fatty acyl chains of POPC. Molecular dynamics simulations were in close agreements with the experimental results regarding the location of DES in phospholipids bilayers.

Preparation of magnetic molecularly imprinted polymers for the rapid detection of diethylstilbestrol in milk samples.

BACKGROUND: Diethylstilbestrol (DES) residues are harmful to human health because of their potential carcinogenic properties. Therefore, it is important to develop a fast and efficient pretreatment method to prevent their harmful effects on human health and the environment. RESULTS: In this paper, two types of magnetic molecularly imprinted polymers (MMIPs) of DES were prepared by bulk polymerization and the sol-gel method, respectively. The synthetic materials were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy and thermogravimetric analysis. Adsorption capacities of the bulk and sol-gel MMIPs were investigated. A rapid detection method was developed using the two types of MMIPs as sorbents, coupled to high-performance liquid chromatography, for the determination of DES residues in milk samples. Under optimized conditions, the limit of detection (S/N = 3) of both methods for DES was 2.0 µg L-1 ; and the linear response range to DES was 0.1-500 mg L-1 . The milk samples were analyzed according to this method with good recoveries of 88.3-97.6 and 90.5-103.5% for the two types of MMIPs, respectively. CONCLUSIONS: The method described had high sensitivity and high selectivity, and could prove to be a new method for the rapid determination of DES residues in milk samples. © 2019 Society of Chemical Industry.

Multi-Residue Method for the Analysis of Stilbene Estrogens in Milk.

The rapid analysis of stilbene estrogens is crucially important in the environment, food and health sectors, but quantitation of lower detection limit for stilbene estrogens persists as a severe challenge. We herein described a homologous and sensitive fluorescence polarization (FP) assay based on estrogen receptor α ligand binding domain (ER-LBD) to monitor stilbene estrogens in milk. Under optimal conditions, the half maximal inhibitory concentrations (IC50) of the FP assay were 9.27 nM, 12.94 nM, and 22.38 nM for hexestrol, dienestrol and diethylstilbestrol, respectively. And the corresponding limits of detection (LOD) values were 2.94 nM, 2.89 nM, and 3.12 nM. Finally, the assay was applied to determine the stilbenes in milk samples where the mean recoveries ranged from 95.76% to 112.78% and the coefficients of variation (CV) below 12.00%. Furtherly, we have focused our study on high cross-reactivity phenomena by using two in silico approaches, including molecular docking analysis and topology analysis. Overall, docking results show that several residues in the hydrophobic pocket produce hydrophobic interactions with the tested drug molecules, which contribute to the stability of their binding. In this paper, we conclude that the FP method is suitable for the rapid detection of stilbenes in milk samples, requiring no expensive analytical equipment or time-consuming sample preparation. This work offers a practical approach that applies bioscience technology in food safety testing and improves analytical speed and laboratory efficiency.

[Determination of four phenolic estrogens in water samples by pressure-assisted electrokinetic injection coupled with capillary electrophoresis].

A capillary electrophoresis (CE) method was developed for the simultaneous separation and determination of four phenolic estrogens (PEs), in which pressure-assisted electrokinetic injection (PAEKI) was adopted as the on-line concentration method to enrich the PEs. Several parameters affecting PAEKI conditions such as injection voltage and injection time, were systematically investigated and compared with the usual parameters. Under the optimized PAEKI conditions (-9 kV, 0.3 psi (ca. 2.1 kPa), 0.4 min), the four PEs separated completely within 7 min. Good linearities were attained in the range of 0.05-5 mg/L for hexestrol and dienestrol, and 0.1-10 mg/L for bisphenol A and diethylstilbestrol, with correlation coefficients (r) over 0.9936. The limits of detection (S/N=3) were 0.0071-0.017 mg/L, and enrichment factors ranged from 11 to 15 compared to normal hydrodynamic injection. The combined micellar electrokinetic chromatographic-PAEKI method developed was used to determine the PEs in tap water and lake water samples; limits of quantification (S/N=10) of 0.029-0.064 mg/L and 0.033-0.079 mg/L were attained, respectively, by the two sample types. Furthermore, recoveries ranged from 75.6% to 110.1% with relative standard deviations (n=5) within 4.6%-11.8%. To use this PAEKI method, researchers would only need to adjust the parameters of the CE apparatus to perform on-line enrichment of analytes, without using other reagents; this demonstrates the simplicity, rapidity, and highly automated nature of this method.

A novel electrochemical sensor based on Fe3O4-doped nanoporous carbon for simultaneous determination of diethylstilbestrol and 17ß-estradiol in toner.

In this paper, Fe3O4-doped nanoporous carbon (Fe3O4-NC) was synthesized through the carbonization of Fe-porous coordination polymer (Fe-PCP), which are also known as metal-organic framework (MOF), and fabricated into an electrochemical sensor for simultaneous analysis of diethylstilbestrol (DES) and 17ß-estradiol (E2) in toner. Fe3O4-NC was characterized by scanning electron microscope (SEM), powder X-ray diffraction (pXRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, N2 adsorption-desorption and so on. It is of great practical significance to achieve the simultaneous determination of the two estrogens because estrogens are co-existing in many real samples. The simultaneous determination of two common estrogens, DES and E2, was achieved through electro-catalytically oxidization at a Fe3O4-NC modified glassy carbon electrode (Fe3O4-NC/GCE). The peak currents of DES and E2 increased linearly as their concentrations increasing from 0.01 to 12 µmol/L and from 0.01 to 20 µmol/L, with detection limits of 4.6 nmol/L and 4.9 nmol/L (S/N = 3), respectively. This work was focused on the simultaneous determination of the two estrogens in toner. Furthermore, the recoveries of DES and E2 were 91.2-110%, in actual toner samples. The experimental results manifest that the sensor with a stronger anti-interference ability can be used for the simultaneous detection of DES and E2 in the actual toner sample.

Simultaneous determination of environmental estrogens: Diethylstilbestrol and estradiol using Cu-BTC frameworks-sensitized electrode.

It is quite important to monitor environmental estrogens in a rapid, sensitive, simple and cost-effective manner due to their wide existence and high toxicity. Using 1,3,5-Benzenetricarboxylic acid (H3BTC) as the ligand and copper ions as the center, Cu-BTC frameworks with surface area of 654.6m(2)/g were prepared, and then used to construct a novel electrochemical sensing platform for diethylstilbestrol (DES) and estradiol (E2). On the surface of Cu-BTC frameworks, two oxidation waves at 0.26V and 0.45V are observed for DES and E2, and the oxidation signals are improved greatly. The prepared Cu-BTC frameworks not only enhance the accumulation efficiency of DES and E2, but also improve their electron transfer ability. The influences of pH value, modification amount of Cu-BTC and accumulation time were examined. As a result, a highly-sensitive, rapid and convenient electrochemical method was developed for the simultaneous determination of DES and E2, with detection limit of 2.7nM and 1.1nM. The practical applications manifest this new sensing system is accurate and feasible.

Evaluation of graphene-based sorbent in the determination of polar environmental contaminants in water by micro-solid phase extraction-high performance liquid chromatography.

A facile method of extraction using porous membrane protected micro-solid phase extraction (µ-SPE) with a graphene-based sorbent followed by high performance liquid chromatography-ultraviolet detector was developed. The reduced graphene oxide (r-GO) (1mg), synthesized from graphite oxide, was enclosed in a polypropylene bag representing the µ-SPE device, which was used for the extraction of estrogens such as estrone, 17ß-estradiol, 17α-ethynylestradiol and diethylstilbestrol in water. The r-GO obtained was identified and characterized by Fourier transform infrared, transmission electron microscopy, scanning electron microscopy and thermogravimetric analysis. The sorbent was loaded with sodium dodecyl sulfate by sonication to prevent agglomeration in aqueous solution. With this method, low limits of detection of between 0.24 and 0.52 ng L(-1) were achieved. For estrogen analysis a linear calibration range of 0.01-100 µg L(-1) was obtained, with the coefficients of determination (r(2)) higher than 0.992. This proposed method was successfully applied to determine estrogens in water.

Determination of Estrogens in Milk Samples by Magnetic-Solid-Phase Extraction Technique Coupled With High-Performance Liquid Chromatography.

A magnetic-solid-phase extraction method coupled with high-performance liquid chromatography and diode array detection has been developed for simultaneous determination of 3 estrogens in milk samples. In this work, Fe3O4 NPs were synthesized by a simple chemical co-precipitation reaction, and the surface of Fe3O4 was modified with cetyltrimethyl ammonium bromide (CTAB; designed as Fe3O4@CTAB). The synthesized Fe3O4@CTAB NPs were characterized by Fourier transformed infrared spectroscopy, scanning electron microscopy, and transmission electron microscope. Fe3O4@CTAB NPs have high binding affinity toward estrone (E1), 17ß-estradiol (17ß-E2), and diethylstilbestrol (DES). Fe3O4@CTAB NPs can be easily separated from sample solutions using an external magnet due to the high super-paramagnetic property. The separation, preconcentration procedure is fast and will be completed in 2 min. Estrogens linear dynamic ranges were achieved in the range of 10 to 1000 ng/mL with regression coefficients (R(2)) higher than 0.9992. The limits of detection were between 0.26 and 0.61 ng/mL. Parameters influencing the recoveries were investigated and optimized. The proposed method was used for the determination of E1, 17ß-E2, and DES in milk samples, and recoveries were ranged from 91.3% to 105.0%, with the relative standard deviations in the range of 2.7% to 4.0%.

Performance of metal-organic framework MIL-101 after surfactant modification in the extraction of endocrine disrupting chemicals from environmental water samples.

The research presented in this paper explored the modification and application of a metal-organic framework, MIL-101, with nonionic surfactant-Triton X-114 in dispersive solid-phase extraction for the preconcentration of four endocrine disrupting chemicals (estrone, 17α-ethynylestradiol, estriol and diethylstilbestrol) from environmental water samples. Triton X-114 molecules could be adsorbed by the hydrophobic surface of the MIL-101 crystals, and thus improved the dispersibility of MIL-101 in aqueous solution by serving as a hydrophilic coating. Cloud point phase separation from Triton X-114 accelerated the separation of extracts from the aqueous matrix. The proposed method combines the favorable attributes of strong adsorption capacity resulting from the porous structure of MIL-101 and self-assembly of Triton X-114 molecules. Post-extraction derivatization using N-methyl-N-(trimethylsilyl)trifluoroacetamide was employed to facilitate the quantitative determination of the extracts by gas chromatography-mass spectrometry. The main factors affecting the preparation of modified MIL-101, and extraction of the analytes, such as the amount of surfactant, the ultrasonic and vortex durations, solution pH and desorption conditions, were investigated in detail. Under the optimized conditions, the present method yielded low limits of detection (0.006-0.023 ng/mL), good linearity from 0.09 to 45 ng/mL (coefficients of determination higher than 0.9980) and acceptable precision (relative standard deviations of 2.2-13%). The surface modified MIL-101 was demonstrated to be effective for the extraction of the selected estrogens from aqueous samples, giving rise to markedly improved extraction performance compared to the unmodified MIL-101.

Dietary exposure to endocrine disrupting chemicals in metropolitan population from China: a risk assessment based on probabilistic approach.

The intake of contaminated foods is an important exposure pathway for endocrine disrupting chemicals (EDCs). However, data on the occurrence of EDCs in foodstuffs are sporadic and the resultant risk of co-exposure is rarely concerned. In this study, 450 food samples representing 7 food categories (mainly raw and fresh food), collected from three geographic cities in China, were analyzed for eight EDCs using high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Besides estrone (E1), other EDCs including diethylstilbestrol (DES), nonylphenol (NP), bisphenol A (BPA), octylphenol (OP), 17ß-estradiol (E2), 17α-ethinylestradiol (EE2), and estriol (E3) were ubiquitous in food. Dose-dependent relationships were found between NP and EE2 (r=0.196, p<0.05), BPA (r=0.391, p<0.05). Moreover, there existed a correspondencebetween EDCs congener and food category. Based on the obtained database of EDCs concentration combined with local food consumption, dietary EDCs exposure was estimated using the Monte Carlo Risk Assessment (MCRA) system. The 50th and 95th percentile exposure of any EDCs isomer were far below the tolerable daily intake (TDI) value identically. However, the sum of 17ß-estradiol equivalents (∑EEQs) exposure in population was considerably larger than the value of exposure to E2, which implied the underlying resultant risk of multiple EDCs in food should be concern. In conclusion, co-exposure via food consumption should be considered rather than individual EDCs during health risk evaluation.

Liquid-phase exfoliated graphene as highly-sensitive sensor for simultaneous determination of endocrine disruptors: diethylstilbestrol and estradiol.

It is quite important to develop convenient and rapid analytical methods for trace levels of endocrine disruptors because they heavily affect health and reproduction of humans and animals. Herein, graphene was easily prepared via one-step exfoliation using N-methyl-2-pyrrolidone as solvent, and then used to construct an electrochemical sensor for highly-sensitive detection of diethylstilbestrol (DES) and estradiol (E2). On the surface of prepared graphene film, two independent and greatly-increased oxidation waves were observed at 0.28V and 0.49V for DES and E2. The remarkable signal enlargements indicated that the detection sensitivity was improved significantly. The influences of pH value, amount of graphene and accumulation time on the oxidation signals of DES and E2 were discussed. As a result, a highly-sensitive and rapid electrochemical method was newly developed for simultaneous detection of DES and E2. The values of detection limit were evaluated to be 10.87 nM and 4.9 nM for DES and E2. Additionally, this new method was successfully used in lake water samples and the accuracy was satisfactory.

Vortex-assisted hollow fibre liquid-phase microextraction technique combined with high performance liquid chromatography-diode array detection for the determination of oestrogens in milk samples.

A rapid, simple, sensitive and environmentally friendly method has been developed for the determination of three oestrogens (17ß-estradiol (17ß-E2), estrone (E1), and diethylstilbestrol (DES)) in milk samples by using vortex-assisted hollow fibre liquid-phase microextraction (VA-HF-LPME) and high performance liquid chromatography. Method is based on the microextraction of oestrogens from sample solution into 15 µL of nonanoic acid as extracting agent, which is placed inside the hollow fibre followed by vortex-mixing. Vortex provided effective and mild mixing of sample solution and increased the contact between analytes and boundary layers of the hollow fibre, thereby enhancing mass transfer rate and leading to high recovery of target analytes. The extraction equilibrium is achieved within 2 min. Parameters influencing the recovery were investigated and optimized. The proposed technique provided good linearity (>0.9984), repeatability (RSD = 2.56-4.38), low limits of detection (0.06-0.17 ng mL(-1)), and high enrichment factor (330).

Comparison of two thin-film microextractions for the analysis of estrogens in aqueous tea extract and environmental water samples by high performance liquid chromatography-ultraviolet detection.

Two thin-film microextractions (TFME), octadecylsilane (ODS)-polyacrylonitrile (PAN)-TFME and polar enhanced phase (PEP)-PAN-TFME have been proposed for the analysis of bisphenol-A, diethylstilbestrol and 17ß-estradiol in aqueous tea extract and environmental water samples followed by high performance liquid chromatography-ultraviolet detection. Both thin-films were prepared by spraying. The influencing factors including pH, extraction time, desorption solvent, desorption volume, desorption time, ion strength and reusability were investigated. Under the optimal conditions, the two TFME methods are similar in terms of the analytical performance evaluated by standard addition method. The limits of detection for three estrogens in environmental water and aqueous tea extract matrix ranged from 1.3 to 1.6 and 2.8 to 7.1 ng mL(-1) by the two TFME methods, respectively. Both approaches were applied for the analysis of analytes in real aqueous tea extract and environmental water samples, presenting satisfactory recoveries ranged from 87.3% to 109.4% for the spiked samples.

Hollow-fiber-supported liquid-phase microextraction using an ionic liquid as the extractant for the pre-concentration of bisphenol A, 17-ß-estradiol, estrone and diethylstilbestrol from water samples with HPLC detection.

A new method for the determination of four endocrine disrupting compounds (EDCs) (bisphenol A, 17-ß-estradiol, estrone and diethylstilbestrol) in water samples has been developed using polypropylene hollow-fiber-supported ionic liquid (IL, 1-Octyl-3-methylimidazolium hexafluorophosphate, [C8MIM][PF6]) microextraction [HF-liquid-phase microextraction (LPME)] combined with high-performance liquid chromatography (HPLC)/UV. This method was used to investigate pollutants in surface water, on the Neijiang River, located at Zhenjiang, Jiangsu Province. Several parameters (sample pH, volume of accepter phase, ionic strength) were investigated. Under the optimum extraction conditions (sample pH, 2.0; volume of extraction solvent, 2.5 µL; ionic strength, 2.57) the proposed method offered: good linearity range, 0.15-100 µg L(-1), with the correlation coefficients (r(2)) of 0.9996, 0.9994, 0.9990 and 0.9984, respectively; low limits of detection, 0.03, 0.05, 0.10, 0.05 µg L(-1) (S/N = 3) for bisphenol A, 17-ß-estradiol, estrone and diethylstilbestrol, respectively; good reproducibility (relative standard deviation (RSD), 8.41, 7.61, 9.00, 7.22%, respectively, n = 5); satisfactory recoveries (80.2-107.1%, n = 5); and high enrichment factors, 5,240, 3,693, 2,425 and 2,086, were achieved, for the four chemicals, respectively. Using the proposed HF-LPME, among 15 sampling sites along Neijiang River, bisphenol A, diethylstilbestrol and 17-ß-estradiol were detected in some sites, all of which were the near suburban sampling sites. The results indicate that the role of municipal sewage is an important source of EDC contamination.

An automated solid-phase microextraction method based on magnetic molecularly imprinted polymer as fiber coating for detection of trace estrogens in milk powder.

A new automated solid-phase micro extraction (SPME) sampling method was developed for quantitative enrichment of estrogens (ES) from milk powder, using magnetic molecularly imprinted polymer (MMIP) as fiber coating. The method (MMIP-SPME) was built with several electromagnetic stainless steel fibers, placed in parallel for simultaneously extraction. The MMIP was synthesized using core-shell Fe3O4@SiO2 nanoparticles (NPs) as magnetic support. Estradiol (E2) was employed as the template molecule, acrylamide (AA) as functional monomer, and ethylene glycol dimethacrylate (EGDMA) as cross-linker. MMIP can be easily absorbed or desorbed from fibers when the current is turned on or off, creating magnetism. Compared to traditional MIP-SPME, the prepared procedure of MMIP-SPME is time-saving and organic solvent-free. The proposed device significantly improved the efficiency of separation and enrichment of estrogens from complex matrices thereby and facilitating the pretreatment steps by electromagnetically controlled extraction fibers to achieve full automation. Several experimental parameters were studied, including extraction and desorption kinetics, solution pH, desorption solution, ratio, and shuttle rate. The newly developed MMIP-SPME showed good sensitivity and high binding capacity, fast adsorption kinetics and desorption kinetics for estrone (E1), estradiol (E2), estriol (E3) and diethylstilbestrol (DES) under optimized conditions. The detection limits for the four estrogens were 1.5-5.5ngg(-1) with excellent reproducibility (RSD values less than 7.1%) when milk powder samples spiked with analytes at 20, 100 and 250ngg(-1) were studied.

Estrogen receptor affinity chromatography: a new method for characterization of novel estrogenic disinfection by-products.

To identify the unknown estrogenic disinfection by-products (DBPs) from the chlorination extract, an effective method based on affinity chromatography with immobilized human recombinant estrogen receptor α (ERα) was developed, which has an advantage in targeting different potential estrogenic compounds from mixed sample simultaneously by comparing their relative binding activities to ER. The new method worked well for six known environmental estrogens. To further test the validity of this method for unknown chemicals, six DBPs of diethylstilbestrol (DES) with relatively strong ER binding affinity after chlorination were isolated and identified. It was found that except for 2-chloro-DES which showed 1.36 times stronger binding affinity than DES, most of the by-products bound to ER much more weakly than DES. All these seven by-products induced a dose-dependent transcriptional activation in two-hybrid-yeast assays. Z,Z-dienestrol (DE) and 2-chloro-DES, which exhibiting the weakest and the strongest binding affinity, were further tested for their transcriptional potential as 0.00243 and 0.014 compared to DES, respectively. However, they were still potential harmful environmental estrogenic disruptors as their estrogenic activities were much stronger than that of bisphenol A (BPA). These results demonstrated that the new method can help to screen unknown estrogenic compounds from mixture more efficiently.

Determination of estrogens and estrogenic activities in water from three rivers in Tianjin, China.

Studies on estrogenic disrupting compounds (EDCs) occurrence and identification of main responsible compounds in river water discharged into the sea are of significance. In the present research, we screened estrogenic activities of 10 river water samples from 3 main rivers discharged into Bohai Sea in Tianjin using a recombinant two-hybrid yeast assay and chemical analysis by gas chromatography-mass spectrometry. All sample extracts induced significant estrogenic activity, with 17beta-estradiol equivalents (EEQ) of raw water ranging from 5.72 to 59.06 ng/L. Six most concerned EDCs in the river water samples including estrone, 17beta-estradiol, 17alpha-ethinylestradiol, estriol, diethylstilbestrol and estradiol valerate were determined, with their concentrations up to 50.70, 31.40, 24.40, 37.20, 2.56, and 8.47 ng/L, respectively. Through causality analysis by comparing the EEQ values of yeast assay and chemical analysis, 17alpha-ethinylestradiol and 17beta-estradiol were identified as the main contributors to the estrogenic effects of the river samples, accounting for the whole estrogenic activities (62.99% to 185.66%), and estrogen antagonistic compounds might presented in the heavy polluted water samples. The proposed approach using both chemical analysis and bioassay could be used for identification and evaluation of the estrogenic activity of EDCs in river water.

Risk assessment of xenoestrogens in a typical domestic sewage-holding lake in China.

Release of domestic sewage leads to accumulation of xenoestrogens in holding waters, especially in closed or semi-enclosed waters such as lakes. In the study, the occurrence, distribution, estrogenic activity and risk of eight xenoestreogens were evaluated in Lake Donghu, China. Nonylphenol (NP), octylphenol (OP), and bisphenol A (BPA) were identified as the main xenoestrogens ranging from tens of ngL(-1) (in the surface water) or ng g(-1)dw (in the suspended particles and sediment) to tens of µgL(-1) or µg g(-1)dw. The sum of 17ß-estradiol equivalents (∑EEQs) ranged from 0.32 to 45.02 ngL(-1) in the surface water, 0.53 to 71.86 ng g(-1)dw in the suspended particles, and 0.09 to 24.73 ng g(-1)dw in the sediment. Diethylstilbestrol (DES) was determined as the main contributor to ∑EEQs followed by NP. The risk assessment showed a higher risk in the surface water than in the suspended particles and sediment in such domestic sewage-holding lake.

An imprinted crystalline colloidal array chemical-sensing material for detection of trace diethylstilbestrol.

Based on a combination of the molecular imprinting technique and polymerized crystalline colloidal array, we have developed an imprinted crystalline colloidal array (ICCA) chemical-sensing material for the real-time and label-free detection of diethylstilbestrol (DES) in aqueous solution. This novel sensing material was prepared by a noncovalent and self-assembly approach using liquid monodispersed DES-imprinted colloidal spheres and was characterized by a three-dimensional (3D) ordered opal structure in which numerous nanocavities were derived from DES imprinting. Thus, the inherent high affinity of the nanocavities allowed ICCA to recognize DES with high specificity, and changes of the ordered periodic structure enabled ICCA to transfer the recognition events into readable optical signals (label-free). Owing to the special opal structure and without interference from the bulk hydrogel film, the ICCA enabled the rapid and sensitive detection of the target analyte. The understanding of the recognizing response has also been advanced by using molecular modeling software to compute rational interaction between the template molecules and the function monomers. After careful optimization of the assay conditions, the ICCA could decrease its diffraction intensity within just 7 min according to the DES concentration from 2 ng mL(-1) to 8.192 µg mL(-1), whereas there were no obvious diffraction intensity changes for the DES analogues. The adsorption results showed that the homogenous structure and large surface area of ICCA could improve its adsorption capacity. Therefore, such a sensing material with high selectivity, high sensitivity, high stability, and easy operation might offer an attractive alternative for establishing optical sensors for the rapid real-time monitoring of different residues in food and the environment.