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

Design and preparation of novel magnetic covalent organic framework for the simultaneous preconcentration and sensitive determination of six aflatoxins in food samples

An innovative core-shell covalent organic framework (COF), Fe3O4@COF (ETTBA-ND), was synthesized through a facile and energy-efficient method. This adsorbent facilitated magnetic solid phase extraction (MSPE) of six AFs prior to LC-MS/MS analysis, achieving one-step purification and enrichment in food matrices. The successful synthesis of the adsorbent was confirmed using various techniques, with adsorption capacities ranging from 46.7 mg/g to 52.3 mg/g. The adsorbent exhibited exceptional adsorption performance in real samples, with recoveries ranging from 80.3 % to 105.6 %, and notable reusability for more than seven cycles. The adsorption mechanism was investigated by density-functional theory and attributed to synergetic effects involving electrostatic and π-π stacking interactions. HPLC-MS/MS quantification revealed strong linear relationships within the 0.01-100 μg/kg range (R2 > 0.9983). The limits of detection ranged from 0.0016 μg/kg to 0.0099 μg/kg, indicating high sensitivity. The newly constructed COF adsorbents exhibit considerable potential for diverse applications in analytical fields that target various hazardous substances.

Magnetic conjugated microporous polymer for rapid extraction and sensitive analysis of environmental endocrine disruptors in environmental waters and dairy products

BACKGROUND

Environmental endocrine disruptors (EEDs) are a class of new pollutants that are diffusely used in the medical industry and animal husbandry. In view of toxicity concerns, elevated levels of EEDs in the environment and food, which cause potential harm to human beings and ecosystems, must be monitored. Determination of EEDs contaminants to ensure environment and food safety has became a major concern worldwide, it is also a challenging task because of their trace level and probable matrices interference. Thus, developing rapid adsorption and efficient analysis methods for EEDs is apparently necessary.

RESULTS

A magnetic conjugated micro-porous polymer (Fe3O4@TbDt) was designed and synthesized, which was endowed with large specific surface area, rich functional groups and magnetic responsiveness. The material showed high extraction efficiency for EEDs via magnetic solid-phase extraction (MSPE). The quantum chemistry calculations showed the adsorption mechanism of Fe3O4@TbDt on EEDs mainly included electrostatic interactions, van der waals forces (N-H … π interaction, C-H … π interaction), and multiple hydrogen bonds. Finally, a trace analysis method for nine EEDs was established combined with HPLC-MS/MS under optimized MSPE conditions. The method showed a good linearity (R2 ≥ 0.996), low limits of detection (0.25-5.1 ng L-1), high precision (RSD of 1.1-8.2 %, n = 6). The applicability of this method was investigated by analyzing four water samples and two dairy products, and satisfactory recovery rates (82.1-100.7 %) were obtained. The proposed method showed the potential for the analysis of EEDs residues in food and environmental samples.

SIGNIFICANCE

The developed MSPE method based on conjugated micro-porous polymers (CMPs) is simple, green, and efficient compared to existing techniques. The application of CMPs provides a new idea for preparing versatile sample pre-treatment materials. What's more, this work has certain reference value for addressing of EEDs residues in the environment and food.

17β-estradiol biosensors based on different bioreceptors and their applications

17β-Estradiol (E2) is a critical sex steroid hormone, which has significant effects on the endocrine systems of both humans and animals. E2 is also believed to play neurotrophic and neuroprotective roles in the brain. Biosensors present a powerful tool to detect E2 because of their small, efficient, and flexible design. Furthermore, Biosensors can quickly and accurately obtain detection results with only a small sampling amount, which greatly meets the detection of the environment, food safety, medicine safety, and human body. This review focuses on previous studies of biosensors for detecting E2 and divides them into non-biometric sensors, enzyme biosensors, antibody biosensors, and aptamer biosensors according to different bioreceptors. The advantages, disadvantages, and design points of various bioreceptors for E2 detection are analyzed and summarized. Additionally, applications of different bioreceptors of E2 detection are presented and highlight the field of environmental monitoring, food and medicine safety, and disease detection in recent years. Finally, the development of E2 detection by biosensor is prospected.

Methacrylate bonded covalent organic framework monolithic column online coupling with high-performance liquid chromatography for analysis of trace estrogens in food

Covalent organic frameworks (COFs) are a burgeoning class of crystalline porous materials with unique properties and have been considered as a promising functional extraction medium in sample pretreatment. In this study, a new methacrylate-bonded COF (TpTh-MA) was well designed and synthesized via the aldehyde-amine condensation reaction, and the TpTh-MA was incorporated into poly (ethylene dimethacrylate) porous monolith by a facile polymerization reaction inside capillary to prepare a novel TpTh-MA monolithic column. The fabricated TpTh-MA monolithic column was characterized with scanning electron microscope, Fourier transform infrared spectrometer, X-ray diffraction, and N₂ adsorption-desorption experiments. Then, the homogeneous porous structure, good permeability and high mechanical stability of TpTh-MA monolithic column was used as separation and enrichment media of capillary microextraction, which was coupled with high-performance liquid chromatography fluorescence detection for online enrichment and analysis of trace estrogens. The main experimental parameters influencing the extraction efficiency were systematically investigated. The adsorption mechanism for three estrogens was also explored and discussed based on hydrophobic effect, π-π affinity and hydrogen bonding interaction, which contributed to its strong recognition affinity to target compounds. The enrichment factors of the TpTh-MA monolithic column micro extraction method for the three estrogens were 107-114, indicating a significant preconcentration ability. Under optimal conditions, a new online analysis method was developed and exhibited good sensitivity and wide linearity range of 0.25-100.0 µg·L^-1 with a coefficient of determination (R²) higher than 0.9990 and a low limit of detection with 0.05-0.07 µg·L^-1. The method was successfully applied for online analysis of three estrogens of milk and shrimp samples and the recoveries obtained from spiking experiments were in range of 81.4-113% and 77.9-111%, with the relative standard deviations of 2.6-7.9% and 2.1-8.3% (n = 5), respectively. The results revealed the great potential for the application of the COFs-bonded monolithic column in the field of sample pretreatment.

A magnetic relaxation switch sensor for determination of 17β-estradiol in milk and eggs based on aptamer-functionalized Fe3 O4 @Au nanoparticles

BACKGROUND

A simple and rapid detection method for 17β-estradiol (E₂ ) in complex food matrix is greatly desirable. A magnetic relaxation switch (MRS) sensor for detecting E₂ based on the aptamer-functionalized gold-coated iron oxide (Fe₃ O₄ @Au) nanocomposite was designed in this study. Fe₃ O₄ @Au nanoparticles (NPs) played as a 'switch' between dispersed and aggregated states, while aptamer served as the recognition unit.

RESULTS

According to the sensing effect of monocomponent relaxation time (T_2W ) for E₂ , the volume ratio of aptamers to Fe₃ O₄ @Au, the sodium chloride (NaCl) concentration, the concentration of Fe₃ O₄ @Au@Apt, and reaction time were optimized to be 4:1, 0.03 mol L^-1 , 4 μmol L^-1 and 15 min, respectively. For the analysis of food sample, the E₂ was quantified over a concentration range of 1 to 100 nmol L^-1 with a detection limit of 7.6 nmol L^-1 for milk samples, while a linearity range of 20 to 100 nmol L^-1 and a detection limit of 8.57 nmol L^-1 for egg samples.

CONCLUSION

These results exhibited that the MRS sensor could be a promising platform for the rapid detecting of E₂ in food sample. © 2021 Society of Chemical Industry.

Preparation, surface functionalization and application of Fe3O4 magnetic nanoparticles

This paper reviews recent developments in the preparation, surface functionalization, and applications of Fe₃O₄ magnetic nanoparticles. Especially, it includes preparation methods (such as electrodeposition, polyol methods, etc.), organic materials (such as polymers, small molecules, surfactants, biomolecules, etc.) or inorganic materials (such as silica, metals, and metal oxidation/sulfide, functionalized coating of carbon surface, graphene, etc.) and its applications (such as magnetic separation, protein fixation, magnetic catalyst, environmental treatment, medical research, etc.). In the end, some existing challenges and possible future trends in the field were discussed.

Detection of four phenolic oestrogens by a novel electrochemical immunosensor based on a hexestrol monoclonal antibody

A novel HEX monoclonal antibody/MACA/nanogold electrochemical immunosensor was constructed to detect four phenolic oestrogens by a nanosized effect, layer by layer self-assembly and antigen–antibody specific immune technology.

Determination of 17β-estradiol in commercial pasteurized and sterilized milk samples in Mashhad, Iran

Due to nutritional facts of milk in human life, the quality assessment of dairy products is of the utmost importance. The aim of the current study was to determine the 17β-estradiol level in commercial pasteurized and sterilized milk brands in Mashhad, Iran. In this regard, 160 samples including 80 pasteurized (40 high-fat and 40 low-fat) and 80 sterilized milk (40 high-fat and 40 low-fat) of widely used brands from different supermarkets were collected. The mean level of 17β-estradiol was 8.2 ± 0.59 pg/ml. The mean amount of estradiol was found to be 7.6 ± 0.47, 7.9 ± 0.45, 8.6 ± 0.63, and 8.9 ± 0.54 pg/ml for the low-fat pasteurized, low-fat sterilized, high-fat pasteurized and high-fat sterilized milk, respectively. There was no significant difference between the amount of estradiol in pasteurized and sterilized milk. As expected, the level of estradiol was statistically higher in high fat milks than that of low-fat milks. Considering the levels of 17β-estradiol measured here and the maximum permissible daily level of external estradiol entered to body through edible products recommended by EU and CAC (3.5 µg), at least in the short term, there will be no remarkable impact on the endocrine system. However, judging the long-term effects of using these products is not easy and simple at all, as cancers develop during a long period of time and has a multifactorial etiology.

Recent advances in the detection of 17β-estradiol in food matrices: A review

Pollution of endocrine disrupting chemicals has become a global issue. As one of the hormonally active compounds, 17β-estradiol produces the strongest estrogenic effect when it enters the organism exogenously including food intakes, bringing potential harmfulness such as malfunction of the endocrine system. Therefore, in order to assure food safety and avoid potential risks of 17β-estradiol to humans, it is of great significance to develop rapid, sensitive and selective approaches for the detection of 17β-estradiol in food matrices. In this review, the harmfulness and main sources of 17β-estradiol are firstly introduced, followed by the description of the principles and applications of different approaches for 17β-estradiol detection including high performance liquid chromatography, electrochemistry, Raman spectroscopy, fluorescence and colorimetry. Particularly, applications in detecting 17β-estradiol in food matrices over the years of 2010-2018 are discussed. Finally, advantages and limitations of these detection methods are highlighted and perspectives on future developments in the detection methods for 17β-estradiol are also proposed. Although many detection approaches can achieve trace or ultratrace detection of 17β-estradiol, further studies should be focused on the development of in-situ and real-time methods to monitor and evaluate 17β-estradiol for food safety.

Trace analysis of estrogens in milk samples by molecularly imprinted solid phase extraction with genistein as a dummy template molecule and high-performance liquid chromatography-tandem mass spectrometry

Dummy molecularly imprinted polymer microspheres (DMIPMS) towards estrogens were synthesized by Pickering emulsion polymerization employing genistein (GEN) as a dummy template molecule. The FTIR analysis indicated the successful preparation of the imprinted polymers, and the characterization results of scanning electron microscopy and nitrogen adsorption desorption measurement indicated that the obtained DMIPMS are in possess of regular spherical shapes, porous structures and narrow diameter distribution, a BET surface area of 402.74 m² g^-1, a total pore volume of 0.568 cm³ g^-1 and a pore diameter of 3.62 nm. The binding capacity and selectivity of DMIPMS were investigated in equilibrium binding experiments and chromatographic evaluation experiments through scatchard analysis and molecular imprinting factor (IF) analysis, respectively. The MIPs showed high binding capacity and excellent selectivity towards seven selected natural and synthetic estrogens, which are Estrone (E1), 17β-estradiol (βE2), estriol (E3), ethinylestradiol (EE2), dienestrol(DS), diethylstilbestrol (DES), and hexestrol (HEX). A method for selective determination of seven estrogens in milk samples via dummy molecularly imprinted solid phase extraction coupled with HPLC-MS/MS was developed, which showed good linearity from 2 to 500 µg L^-1 with a correlation coefficient (R2) of more than 0.999. The detection limits were within the range of 0.10-0.35 µg L^-1 and the recoveries of the seven estrogens at three spiking levels (10,100,250 µg L^-1) ranged from 88.9% to 102.3% with relative standard deviation (RSD, n = 5) for intra-day and inter-day assays varied from 0.8% to 4.5%. The developed method is thus proven to be efficient and reliable for regular monitoring of trace estrogens in complex matrices such as milk samples.

Determination of Mirabegron in rat plasma by UPLC-MS/MS after oral and intravenous administration

Mirabegron is a kind of β3 adrenergic receptor agonist which is an effective drug for the treatment of overactive bladder. In this research, a UPLC-MS/MS method is developed and validated for the study of mirabegron pharmacokinetic in rats. A protein precipitation method is applied for sample preparation with acetonitrile. m/z 397.3→379.6, m/z 326.4→121.0 for mirabegron, tolterodine (IS), respectively in the positive ion mode was performed for quantitation. The method is reliable and reproducible in our study (intra-day precision≤11.06%, inter-day precision≤11.43%) with concentration curves linear from 5 to 2500 ng/mL(R2>0.999). Stability studies demonstrated that mirabegron was stable under a variety of storage conditions. This method was successfully applied for determining mirabegron in rats after oral and intravenous administration.