Dummy molecularly imprinted magnetic nanoparticles for dispersive solid-phase extraction and determination of bisphenol A in water samples and orange juice

Assessing dietary bisphenol A exposure among Koreans: comprehensive database construction and analysis using the Korea National Health and Nutrition Examination Survey

Bisphenol A (BPA) exposure primarily occurs through dietary intake. This study aimed to estimate the extent of dietary BPA exposure among Koreans. A thorough literature search was conducted to establish a BPA content database encompassing common foods consumed in Korea, including various food raw materials and processed food products. Dietary exposure levels were estimated by integrating the constructed BPA database with comprehensive nationwide 24 h-dietary recall datasets. The finding revealed that dietary BPA exposure was low for most Koreans, with a mean of 14.5 ng/kg bw/day, but was higher for preschool-age children (over 23 ng). Canned foods accounted for 9-36% of the total dietary exposure of the highest dietary exposure groups; while across all age groups, a considerable amount was derived from canned tuna, contribution of canned fruits and canned coffee (milk-containing) was high for preschool-age children and adults, respectively. Notably, for adults, a substantial proportion also stemmed from beer packaged in cans. While diet contributed over 80% of aggregate exposure for most age groups, preschool-age children experienced 60% exposure through diet due to additional exposure from indoor dust. Even at the high exposure scenario, aggregate BPA exposure levels remained lower than the current tolerable daily intake (TDI) set by the Korean agency (20 μg/kg bw/day). Nevertheless, most Koreans were exposed to BPA levels surpassing the strictest TDI (0.2 ng/kg bw/day) set by the European Food Safety Authority.

Acid induced dispersive liquid-liquid microextraction based on in situ formation of hydrophobic deep eutectic solvents for the extraction of bisphenol A and alkylphenols in water and beverage samples

This study describes the development of an acid induced dispersive liquid-liquid microextraction method based on the in situ formation of hydrophobic deep eutectic solvents for the extraction of bisphenol A and alkylphenols from environmental water and beverage samples. Hydrochloric acid altered the hydrophilic-hydrophobic state of fatty acid salts to obtain hydrophobic fatty acids, which formed hydrophobic deep eutectic solvents with analytes in situ to extract the analytes. Under optimized conditions, the limits of detection and limits of quantitation were 0.03-0.1 μg L-1 and 0.12-0.3 μg L-1, the intraday and interday relative standard deviations were less than 3.9 %, and the enrichment factor was 29-32. The recoveries of bisphenol A and alkylphenols were 95.9-104.9 % and 86.9-105.0 %, respectively. The extraction process used only hydrochloric acid and fatty acid salts, and the extraction process required less than 1 min. This method has the advantages of simplicity, speed, low cost and environmental friendliness.

Potential application of 2D nano-layered MXene in analysing and remediating endocrine disruptor compounds and heavy metals in water

With the advancement of technologies and growth of the economy, it is inevitable that more complex processes are deployed, producing more heterogeneous wastewater that comes from biomedical, biochemical and various biotechnological industries. While the conventional way of wastewater treatment could effectively reduce the chemical oxygen demand, pH and turbidity of wastewater, trace pollutants, specifically the endocrine disruptor compounds (EDCs) that exist in µg L-1 or ng L-1 have further hardened the detection and removal of these biochemical pollutants. Even in small amounts, EDC could interfere human's hormone, causing severe implications on human body. Hence, this review elucidates the recent insights regarding the effectiveness of an advanced 2D material based on titanium carbide (Ti3C2Tx), also known as MXene, in detecting and removing EDCs. MXene's highly tunable feature also allows its surface chemistry to be adjusted by adding chemicals with different functional groups to adsorb different kinds of EDCs for biochemical pollution mitigation. At the same time, the incorporation of MXene into sample matrices also further eases the analysis of trace pollutants down to ng L-1 levels, thereby making way for a more cleaner and comprehensive wastewater treatment. In that sense, this review also highlights the progress in synthesizing MXene from the conventional method to the more modern approaches, together with their respective key parameters. To further understand and attest to the efficacy of MXene, the limitations and current gaps of this potential agent are also accentuated, targeting to seek resolutions for a more sustainable application.

The construction of highly selective surface molecularly imprinted polymers based on Cu(II) coordination for the detection of bisphenol A

Herein, we designed and constructed a highly selective MIPs for bisphenol A (BPA) named Cu-MIPs@CS based on Cu(II) coordination. The synthesis of Cu-MIPs@CS employed a dummy template strategy and surface imprinting technology, with chitosan (CS) as the substrate linked to imprinted layers via Cu2+ bridging. 4-vinylpyridine acted as the functional monomer, capable of forming a complex with the template ketoprofen, while ethylene glycol dimethacrylate served as the cross linker. Cu-MIPs@CS exhibited a significantly enhanced imprinting factor of 14.78 for BPA, which was approximately 6.6 times higher than that of imprinted materials without Cu2+ (MIPs@CS). Cu-MIPs@CS exhibited a selective factor of 12.74 towards resorcinol, which possessed identical functional groups but a smaller size than BPA, representing an enhancement of selectivity by 12.25-fold compared to MIPs@CS. More importantly, Cu-MIPs@CS exhibited a superior discrimination ability between BPA and its structural analogue, diphenolic acid, with an excellent selective factor of 2.93, highlighting its significance in distinguish the structural analogue of BPA. In contrast, MIPs@CS lack sufficient selectivity to differentiate between them. Through exploration of adsorption mechanism of Cu-MIPs@CS, it was demonstrated that the incorporation of Cu2+ significantly reduced nonspecific adsorption, but also facilitated the creation of more selective imprinted cavities by introducing metal coordination, thereby notably enhancing the selectivity of Cu-MIPs@CS. Finally, the developed Cu-MIPs@CS were applied as the solid phase extraction adsorbent and combined with HPLC-DAD detection to establish an analytical method towards BPA in drinking water samples. The limit of detection of the method was 0.14 μg L-1 and recoveries ranged from 95.6 % to 101 %. This work provided broad prospects for construction of highly selective MIPs and accurate quantification of trace amounts of BPA.

Synthesis and characterization of pH-responsive deep eutectic solvent followed by HPLC for trace determination of bisphenol A in water samples

A microextraction based on pH-responsive deep eutectic solvent combined with high-performance liquid chromatography was developed for the separation, preconcentration, and determination of bisphenol A in water samples. Five deep eutectic solvents were prepared using thymol (hydrogen bond acceptor) and 6-, 8-, 9-, 10-, and 12-carbon carboxylic acids (hydrogen bond donor), and were used as extraction solvent. Herein, by alkalinizing the environment, phase transition takes place, and by adding acid, phase separation and extraction of analytes occur simultaneously. Some important parameters on the extraction such as deep eutectic solvent type, molar ratio of deep eutectic solvent components, deep eutectic solvent volume, potassium hydroxide concentration, hydrochloric acid volume, extraction time, and salt addition were optimized. Under the optimum conditions, intra- and interday precisions of the method based on seven replicate measurements of 10 μg L-1 of bisphenol A in water samples were 2.2% and 4.3%, respectively. The analytical performance of the method showed linearity over the concentration of 0.05-50 μg L-1 with the detection limit of 0.02 μg L-1 . The accuracy of the method was confirmed by spiking different concentrations of bisphenol A in real water samples and obtaining relative recoveries in the range of 92.5%-105.2%.

Preparation of amino-functionalized triazine-based hyper-crosslinked polymer for efficient adsorption of endocrine disruptors

Herein, two novel amino-functionalized triazine-based hyper-crosslinked porous polymer (NH2-HCPs) (named as DPT-BB, DPT-DX) were designed and synthesized by direct crosslinking of 2,4-diamino-6-phenyl-1,3,5-triazine (DPT) with 4,4'-bis(chloromethyl)-1,1'-biphenyl (BB) or α, α'-dichloro-p-xylene (DX). Thanks to the amino functional group and hyper-crosslinked porous structure, NH2-HCPs displayed remarkable adsorption ability for phenolic EDCs. The adsorption mechanism mainly involved hydrogen bond, π-π interaction, hydrophobic interaction and pore filling. Thus DPT-BB was applied as solid phase extraction sorbent to extract phenolic EDCs from water and orange juice samples prior to quantitative analysis by high performance liquid chromatography. Under the optimal conditions, detection limit as low as 0.07-0.2 ng mL-1 for water and 0.1-0.27 ng mL-1 for orange juice was achieved. Good recoveries spanned the range of 83.5%-114% were obtained for spiked samples, with relative standard deviations below 8.9%. The results demonstrated that the developed method displayed excellent practicability for sensitive analysis of EDCs.

Synthesis of composite materials combining magnetic metal-organic frameworks and conjugated organic frameworks for selective extraction of carbendazim and thiabendazole residues from Chinese herbal medicine samples

A magnetic metal-organic framework MIL-68(Al) and a covalent organic framework were used as magnetic solid-phase extraction (MSPE) adsorbents in combination with high-performance liquid chromatography ultraviolet detection (HPLC-UV) to detect carbendazim (CBZ) and thiabendazole (TBZ). The main parameters affecting the extraction in the MSPE process were studied and optimized. Fe3O4@MIL-68(Al) coated with 1,3,5-tris(4-aminophenyl)benzene and terephthaldehyde (Fe3O4@MIL-68(Al)@TAPB-PDA-COF) was analyzed and verified. The material was proven to be suitable for adsorbing CBZ and TBZ. Various adsorption models were used to study its adsorption mechanism. The adsorption results were in good agreement with the pseudo-second-order kinetic model and Langmuir isotherm model. The maximum adsorption capacities of Fe3O4@MIL-68(Al)@TAPB-PDA-COF over CBZ and TBZ were 54.24 and 67.87 mg g-1, respectively, and the equilibrium adsorption time was 200 min. Fe3O4@MIL-68(Al)@TAPB-PDA-COF with excellent recyclability showed higher adsorption capacity and selectivity. A method based on Fe3O4@MIL-68(Al)@TAPB-PDA-COF combined with HPLC-UV was established under the optimal extraction conditions and used to separate and detect trace imidazole drugs in Chinese herbal samples, achieving a low limit of detection (0.65-1.30 μg L-1) with excellent linear correlation (r > 0.999). The recovery rate and relative standard deviation were 86.05-99.78 % and 0.15-4.90 %, respectively. Therefore, the Fe3O4@MIL-68@TAPB-PDA-COF can be regarded as an effective adsorbent for the pretreatment of CBZ and TBZ drugs in Chinese herbal samples.

Ultrasound-assisted adsorption approach for desulfurization of n-heptane using nitrogen-doped magnetic carbon dot nanocomposite

Desulfurization is an important process that not only affects the quality and performances of fuels but also is of great importance from environmental aspects. In this research, nitrogen-doped magnetic carbon dots nanocomposite was synthesized and characterized, and it's potential in adsorptive removal of thiophenes (i.e., thiophene, benzothiophene, and dibenzothiophene) from n-heptane (i.e., as model fuel) was investigated. After optimization of adsorption process, the removal efficiency was obtained above 95% for all of studied thiophenes. Besides that, it was concluded that using ultrasound during the adsorption process could enhance the maximum adsorption capacity. Langmuir model was able to appropriately describe the adsorption isotherm data, where the maximum equilibrium adsorption capacities for thiophene, benzothiophene and dibenzothiophene were obtained as 90.22, 96.51 and 100.38 mgg-1, respectively. The analysis of kinetic data also revealed that all thiophenes were being adsorbed following Pseudo-second-order model. To regenerate the adsorbent, the desorption process was also investigated using different solvents under different conditions, methanol was found as effective solvent for regeneration. The proposed adsorbent was used successfully for the removal of pollutants in a gasoline sample.

Synthesis of amine-functionalized magnetic porous organic polymers for effective extraction of phenolic endocrine disrupting chemicals

Amine-functionalized porous organic polymers (EDA-POP-PC and EDA-POP-BT) were prepared by post-modification of POP-PC and POP-BT with ethylenediamine (EDA) for the first time. The POP-PC and POP-BT were obtained through Friedel-Crafts acylation reaction of potassium tetraphenylborate with p-phthaloyl chloride (PC) and 1,3,5-benzenetricarbonyl trichloride (BT), respectively. The EDA-POPs exhibited superior adsorption capacity for phenolic endocrine disrupting chemicals (EDCs). After magnetically functionalization, the obtained M-EDA-POP-PC was employed as a magnetic adsorbent for enrichment of phenolic EDCs from real samples prior to high performance liquid chromatography-ultraviolet detection. The current strategy showed low detection limits (S/N = 3) of 0.02-0.07, 0.04-0.08 and 0.04-0.10 ng mL-1 for river water, white peach juice and lychee juice, respectively. The method recoveries were 81.7%-115% with relative standard deviations below 8.6%. The proposed strategy showed good practicality for sensitive determination of phenolic EDCs in real samples.

Small nanofibrous disks for preconcentration of environmental contaminants followed by direct in-vial elution and chromatographic determination

A novel method for the extraction of river water contaminants as model analytes of ranging polarities, including bisphenols A, C, S, Z, fenoxycarb, kadethrin, and deltamethrin, using small compact fibrous disks has been developed and validated. Polymer nanofibers and microfibers prepared from poly(3-hydroxybutyrate), polypropylene, polyurethane, polyacrylonitrile, poly(lactic acid), and polycaprolactone doped with graphene were evaluated in terms of extraction efficiency, selectivity, and stability in organic solutions. Our novel extraction procedure comprised preconcentration of analytes from 150 mL river water to 1 mL of eluent using a compact nanofibrous disk freely vortexed in the sample. Small nanofibrous disks with a diameter of 10 mm were cut from a compact and mechanically stable 1-2 mm thick micro/nanofibrous sheet. After 60 min extraction in a magnetically stirred sample located in a beaker, the disk was removed from the liquid and washed with water. Then, the disk was inserted into a 1.5 mL HPLC vial and extracted with 1.0 ml methanol upon short intensive shaking. Our approach avoided the undesired problems related to the manual handling typical of "classical" SPE procedure since the extraction was carried out directly in the HPLC vial. No sample evaporation, reconstitution, or pipetting was required. The nanofibrous disk is affordable, needs no support or holder, and its use avoids creation of plastic waste originating from disposable materials. Recovery of compounds from the disks was 47.2-141.4% depending on the type of polymer used and the relative standard deviations calculated from 5 extractions ranged from 6.1 to 11.8% for poly(3-hydroxybutyrate), 6.3-14.8% for polyurethane, and 1.7-16.2% for polycaprolactone doped with graphene. A small enrichment factor was obtained for polar bisphenol S using all sorbents. A higher preconcentration reaching up to 40-fold was achieved for lipophilic compounds such as deltamethrin when using poly(3-hydroxybutyrate) and graphene-doped polycaprolactone.

Determination of trace bisphenols in milk based on Fe3O4@NH2-MIL-88(Fe)@TpPa magnetic solid-phase extraction coupled with HPLC

Herein, a covalent organic framework (COF) was grown on a magnetic metal-organic framework (MOF) by a solvothermal method for the efficient extraction of bisphenols (BPs). The magnetic solid-phase extraction (MSPE) of four bisphenols (bisphenol A, bisphenol B, bisphenol AF and bisphenol C) was carried out without adjusting the pH and salt concentration. When 30 mg Fe₃O₄@NH₂-MIL-88(Fe)@TpPa was used to adsorb for 25 min, 6 mL methanol was used to elute for 20 min, and the extract was detected by high-performance liquid chromatography (HPLC). The proposed method has a low detection limit of 0.011-0.036 ng mL^-1, a wide linear range of 0.05-100 ng mL^-1, and a correlation coefficient (R²) of 0.9980-0.9998. The intra-day and inter-day precisions are 0.74-2.54% and 1.68-3.72%, respectively. Bisphenol A was determined by applying the proposed method to the determination of actual milk samples. The standard addition experiment showed that the relative recovery of the four bisphenols was 85.70-119.7%. Pseudosecond-order, first-order, Langmuir and Freundlich models were applied to explore the adsorption characteristics of Fe₃O₄@NH₂-MIL-88(Fe)@TpPa. In general, the established Fe₃O₄@NH₂-MIL-88(Fe)@TpPa-MSPE-HPLC-UV method exhibits attractive sensitivity, simple manipulation, and excellent reusability, and it has excellent prospects for the detection of trace BPs in complex milk matrices.

Solid phase extraction with rotating cigarette filter for determination of bisphenol A in source and drinking water: computational and analytical studies

An ultrasound assisted solid phase extraction method using rotating cigarette filter is developed herein to preconcentrate and determine trace amount of bisphenol in source and drinking water. Qualitative and quantitative measurements were performed using high-performance liquid chromatography coupled with ultra violet detector. Sorbent-analyte interactions were thoroughly investigated computationally and experimentally using molecular dynamics simulations; and attenuated total reflectance Fourier transform infrared spectroscopy, and Raman spectroscopy, respectively. Various extraction parameters were investigated and optimized. Under the optimal conditions, the results were linear in a low scale range of 0.01-55 ng/mL with correlation coefficient of 0.9941 and a low limit of detection (0.04 ng/mL, signal/noise = 3:1). A good precision (intra-day relative standard deviation ≤ 6.05%, inter-day relative standard deviation ≤ 7.12%) and recovery (intra-day ≥ 98.41%, inter-day ≥ 98.04%)) are obtained. Finally, the proposed solid phase extraction method offered a low cost, simple, fast, and sensitive analytical method to determine trace amount of bisphenol A in source and drinking water samples with chromatographic detection.

Comparison of three cyclodextrins to optimize bisphenol A extraction from source water: Computational, spectroscopic, and analytical studies

Computationally and spectroscopically assisted analytical comparative investigation into the extraction of bisphenol A using three cyclodextrins, that is, α, β, and γ respectively, were performed. A simple, self-tailored μ-solid-phase extraction podium was used to extract bisphenol A from water samples, and high-performance liquid chromatography-ultraviolet was used for the qualitative and quantitative analysis of bisphenol A. Density functional theory first principle calculations, attenuated total reflectance Fourier-transform infrared spectroscopy and Fourier-transform Raman spectroscopy data supports the analytical selection of β-cyclodextrin as the adsorbent for bisphenol A extraction. Analytical optimization of various parameters including sample volume, sample pH, eluting solvent and its volume was performed to discover the most proper conditions for maximum extraction. Under the optimized conditions, a limit of detection value of 0.70 ng/ml and a limit of quantification value of 2.31 ng/ml was achieved with β-cyclodextrin, with recovery (%) values over 98.40-102.50 in real source water samples. Overall, well assisted by comprehensive computational and spectroscopic studies, a novel, simple, sensitive and economic analytical method was developed for the extraction of bisphenol A from source water using cyclodextrin.

Recent molecularly imprinted polymers applications in bioanalysis

Molecular imprinted polymers (MIPs) as extraordinary compounds with unique features have presented a wide range of applications and benefits to researchers. In particular when used as a sorbent in sample preparation methods for the analysis of biological samples and complex matrices. Its application in the extraction of medicinal species has attracted much attention and a growing interest. This review focus on articles and research that deals with the application of MIPs in the analysis of components such as biomarkers, drugs, hormones, blockers and inhibitors, especially in biological matrices. The studies based on MIP applications in bioanalysis and the deployment of MIPs in high-throughput settings and optimization of extraction methods are presented. A review of more than 200 articles and research works clearly shows that the superiority of MIP techniques lies in high accuracy, reproducibility, sensitivity, speed and cost effectiveness which make them suitable for clinical usage. Furthermore, this review present MIP-based extraction techniques and MIP-biosensors which are categorized on their classes based on common properties of target components. Extraction methods, studied sample matrices, target analytes, analytical techniques and their results for each study are described. Investigations indicate satisfactory results using MIP-based bioanalysis. According to the increasing number of studies on method development over the last decade, the use of MIPs in bioanalysis is growing and will further expand the scope of MIP applications for less studied samples and analytes.

Application of a modified MWCNT-based d-µSPE procedure for determination of bisphenols in soft drinks

Herein, a facile dispersive micro-solid phase extraction (d-µSPE) procedure using carboxylated multi-walled carbon nanotubes modified with silver nanoparticles (Ag/MWCNTs-COOH) was successfully developed for the adsorption and subsequent determination of low levels of two well-known contaminants, namely bisphenol A and S (BPA and BPS) in water and soft drink samples. The detection and measurement of the above-mentioned compounds were performed by HPLC-UV instrument. The applied d-µSPE procedure has several advantages such as rapidity, high degree of sensitivity, precision and efficiency. A combination of polar/non-polar interactions seems to play a key role in the adsorption process. Under the optimized conditions, the calibration curves were linear over the concentration range of 1-500 µg/L for the both targets. The practical limit of quantifications (LOQ) for the both analytes were determined to be 1.0 µg/L. The average relative recoveries obtained from the fortified samples varied between 92 and 110% with the relative standard deviations (RSD%) of 2.9-9.5%.

Association of serum bisphenol AF concentration with depressive symptoms in adolescents: A nested case-control study in China

BACKGROUND

As an important alternative to bisphenol A (BPA), bisphenol AF (BPAF) is widely used and can be detected in multiple human biological samples. However, there are few studies on neurotoxicity of BPAF at present. In particular, no epidemiological studies have investigated BPAF in relation to depressive symptoms in adolescents. Here, our study aimed to evaluate the associations between serum BPAF concentrations and depressive symptoms in adolescents.

METHODS

A nested case-control study within an ongoing longitudinal prospective adolescent cohort that was established in Huaibei, China was conducted. A total of 175 participants who had new-onset depressive symptoms (cases) and 175 participants without depressive symptoms (controls) were included. Serum BPAF concentrations was measured using ultra-high-performance liquid chromatography-tandem mass spectrometry. The associations between BPAF exposure and the risk of depressive symptoms in adolescents were assessed using conditional logistic regression. The dose-response relationship between BPAF level and depressive symptoms was estimated using restricted cubic spline analyses.

RESULTS

In this study, the detection rate of serum BPAF was 100%, and the median (interquartile range, IQR) serum BPAF concentration was 5.24 (4.41-6.11) pg/mL in the case group and 4.86 (4.02-5.77) pg/mL in the control group (P = 0.009). Serum BPAF exposure was a risk factor for depressive symptoms (odds ratio (OR)= 1.132, 95% confidence interval (CI):1.013-1.264). After adjustment for all for confounders, compared with the low-exposure group, the high-exposure group had a 2.806-fold increased risk of depressive symptoms (OR=2.806, 95% CI: 1.188-6.626). Stratified analysis by sex revealed that males were more vulnerable to BPAF exposure than females. After adjustment for all confounders, compared with the low-exposure group, the relative risk of depressive symptoms in the high-exposure group was 3.858 (95% CI: 1.118-12.535) for males, however, no significant association between BPAF exposure and depressive symptoms was found in females. In addition, there was a marked linear association between BPAF exposure and the risk of depressive symptoms in the total population and in males.

CONCLUSIONS

The adolescents in this study were widely exposed to low levels of BPAF. A significant positive association was found between serum BPAF levels and the risk of depressive symptoms. The association was significantly modified by sex, and males were more vulnerable to BPAF exposure than females.

Preparation of Magnetic Metal-Organic Frameworks@Molecularly Imprinted Nanoparticles for Specific Extraction and Enrichment of Bisphenol A in Food

Metal-organic frameworks (MOFs) with systematically tailored structures have been suggested as promising precursors to the preparation of diverse functional materials. Herein, a facile and versatile layer-by-layer strategy without any special surface modifications has been proposed for the preparation of magnetic metal-organic frameworks (MMOFs) supported molecularly imprinted polymer nanoparticles (MMOFs@MIP), which are based on a magnetically susceptible core conjugated with an imidazole-derived self-assembled layer and a silane-based imprinted shell. The obtained MMOFs@MIPs, which integrated the advantages of Fe₃O₄, MOFs, and MIPs, were characterized and exhibited good magnetic properties, a rapid mass transfer rate, and an excellent adsorption selectivity as well as capacity for the targeted molecular - bisphenol A (BPA). Moreover, the MMOFs@MIPs were employed as adsorbents in magnetic solid phase extraction (MSPE) to selectively bind and rapidly separate BPA from real samples with satisfactory recoveries ranging from 88.3% to 92.3%. More importantly, the desirable reusability of MMOFs@MIP was also evaluated, and the recoveries still maintained above 88.0% even after five re-use cycles. Furthermore, combined with high-performance liquid chromatography (HPLC) analysis, a novel MSPE-HPLC method was developed, enabling the highly selective and sensitive detection of BPA in a wide linear range of 0.5–5000 μg L⁻¹ with a low limit of detection (LOD) of 0.1 μg L⁻¹. This work contributes a promising method for constructing various functional nanoparticles @MOFs@MIP hybrid materials for applications in many different fields.

Fabrication of Magnetic Al-Based Fe3O4@MIL-53 Metal Organic Framework for Capture of Multi-Pollutants Residue in Milk Followed by HPLC-UV

The efficient capture of multi-pollutant residues in food is vital for food safety monitoring. In this study, in-situ-fabricated magnetic MIL-53(Al) metal organic frameworks (MOFs), with good magnetic responsiveness, were synthesized and applied for the magnetic solid-phase extraction (MSPE) of chloramphenicol, bisphenol A, estradiol, and diethylstilbestrol. Terephthalic acid (H₂BDC) organic ligands were pre-coupled on the surface of amino-Fe₃O₄ composites (H₂BDC@Fe₃O₄). Fe₃O₄@MIL-53(Al) MOF was fabricated by in-situ hydrothermal polymerization of H₂BDC, Al (NO₃)₃, and H₂BDC@Fe₃O₄. This approach highly increased the stability of the material. The magnetic Fe₃O₄@MIL-53(Al) MOF-based MSPE was combined with high-performance liquid chromatography-photo diode array detection, to establish a novel sensitive method for analyzing multi-pollutant residues in milk. This method showed good linear correlations, in the range of 0.05–5.00 μg/mL, with good reproducibility. The limit of detection was 0.004–0.108 μg/mL. The presented method was verified using a milk sample, spiked with four pollutants, which enabled high-throughput detection and the accuracies of 88.17–107.58% confirmed its applicability, in real sample analysis.

A ZnFe2O4-catalyzed segment imprinted polymer on a three-dimensional origami paper-based microfluidic chip for the detection of microcystin

Microcystin has been causing serious environmental pollution; however, the recognition of such compounds is still challenging because of low abundance and coexisting interfering species. In this contribution, we develop a novel microfluidic paper-based colorimetric sensor by exploiting molecular imprinting technology and Fenton reaction for on-site microcystin-RR determination in complex water samples using a smartphone.

Sex-specific effects of bisphenol S with tissue-specific responsiveness in adult zebrafish: The antiandrogenic and antiestrogenic effects

This study investigates the adverse effects and the associated underlying mechanism of bisphenol S (BPS) exposure on reproductive endocrine activity in adult zebrafish. Fish were exposed for 21 days to different BPS concentrations (0, 8, 40, and 200 µg/mL) determined via the lowest observed adverse effect level (LOAEL, i.e., < EC₁₅ = 250 µg/mL) for zebrafish embryos. Exposure to 200 µg/mL BPS in female zebrafish in the absence of vitellogenic oocytes or the presence of degenerated oocytes in the ovary significantly decreased the biosynthesis of hepatic vitellogenin (VTG) mRNA, while hepatic VTG mRNA in male fish abundance was significantly elevated (P < 0.05). The levels of gonadal steroids were significantly increased in female zebrafish, while in male zebrafish, the levels of endogenous androgens were reduced (P < 0.05). However, the activities of 17β-estradiol and aromatase in male zebrafish were significantly elevated in all BPS exposure groups in male zebrafish (P < 0.05). Interestingly, thyroid hormone levels and residual whole-body BPS levels increased in female and male zebrafish with increasing exposure concentrations. A novel finding is that the response to BPS depends on zebrafish sex and tissue-specific responsiveness to the accumulation of BPS, suggesting that BPS may cause long-term environmental problems in adult zebrafish through tissue-specific suppression and hormonal imbalance.

Molecularly Imprinted Polymers for Dispersive (Micro)Solid Phase Extraction: A Review

The review describes the development of batch solid phase extraction procedures based on dispersive (micro)solid phase extraction with molecularly imprinted polymers (MIPs) and magnetic MIPs (MMIPs). Advantages and disadvantages of the various MIPs for dispersive solid phase extraction and dispersive (micro)solid phase extraction are discussed. In addition, an effort has also been made to condense the information regarding MMIPs since there are a great variety of supports (magnetite and magnetite composites with carbon nanotubes, graphene oxide, or organic metal framework) and magnetite surface functionalization mechanisms for enhancing MIP synthesis, including reversible addition-fragmentation chain-transfer (RAFT) polymerization. Finally, drawbacks and future prospects for improving molecularly imprinted (micro)solid phase extraction (MIMSPE) are also appraised.

Development of hydrophilic magnetic molecularly imprinted polymers for the dispersive solid-phase extraction of sulfonamides from animal-derived samples before HPLC detection

Highly hydrophilic magnetic molecularly imprinted polymers were prepared through a surface imprinting technique for dispersive solid-phase extraction coupled with high-performance liquid chromatography to detect trace levels of ten sulfonamides in animal-derived samples. The obtained imprinted polymers were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and adsorption experiments, which exhibited excellent specific adsorption for template sulfamethazine in aqueous solution. Moreover, the adsorption process could be completed within 25 min. Under the optimum conditions, the method exhibits good linear performance in the range of 5-to 10 mg/L, limits of detection ranging from 0.57 to 1.50 μg/L, and good recoveries of 85.09-110.93% in the spiked samples (chicken, cow milk, and goat milk). The proposed detection method not only avoids the use of organic solvents but also simplifies the pretreatment procedure via excellent magnetic properties. Furthermore, the method shows great potential for the rapid detection of drug residues.

Surfactant-coupled titanium dioxide coated iron-aluminium mixed metal hydroxide for magnetic solid phase extraction of bisphenols in carbonated beverages

In this work, the magnetic sorbents based on different surfactant-coupled titanium dioxide coated iron-aluminium mixed metal hydroxide were investigated as sorbent for extraction of bisphenol compounds. The structure, morphology, and magnetic property of the synthesized sorbents were investigated. The cetyltrimethylammonium bromide-titanium dioxide coated iron-aluminium mixed metal hydroxide (Fe-Al MMH@TiO2-CTAB) exhibited excellent extraction performance toward bisphenols and was selected as the sorbent for development of magnetic solid phase extraction (MSPE) method. The entire MSPE process was optimized, and the extract was analyzed by high performance liquid chromatography with photodiode array detector. The method provided wide linear calibration ranges for bisphenols between 0.3-6000 μg L-1 with maximum enrichment factors of 280. The limits of detection and limits of quantification were in the ranges of 0.08-0.3 and 0.3-1.0 μg L-1, respectively. The proposed MSPE method was tested for determination of bisphenols in carbonated beverages. The studied carbonated beverages were mostly free of bisphenol contamination; however, BPS, BPA and BPB were detected in samples taken from defective cans. The relative recoveries ranging of 80.2-118.9% were obtained. The as-prepared Fe-Al MMH@TiO2-CTAB sorbent provided high sorption capacities in the range of 2215-2451 mg kg-1 and could be a promising material for bisphenols in beverage samples.

Dual-template magnetic molecularly imprinted polymer-based sorbent for simultaneous and selective detection of phenolic endocrine disrupting compounds in foodstuffs

In this research, an efficient (94.9-99.4%) and fast (5 min) method has been developed and validated for simultaneous identification and quantification of phenolic endocrine disrupting compounds with an emphasis on bisphenol A (BPA) and 4-cumylphenol (4-CP) in food stuffs using a dual-template magnetic, molecularly-imprinted polymer (dt-MMIP). The dt-MMIP was synthesized by a sol-gel method using Fe₃O₄@SiO₂ (as the core) and BPA and 4-CP (as templates). The dt-MMIP was coupled with magnetic solid phase extraction to simultaneously detect BPA and 4-CP in food samples. BPA was measured from bottled water and fruit juice samples samples at 0.36 and 0.24 ng mL^-1, respectively, while 4-CP in those samples was 0.33 and 0.16 ng mL^-1, respectively. Their detection limits were estimated as 0.04 and 0.05 ng mL^-1, respectively. The developed dt-MMIP method was highly reproducible, while maintaining a good cyclability up to 20 cycles.

Highly sensitive determination of endocrine disrupting chemicals in foodstuffs through magnetic solid-phase extraction followed by high-performance liquid chromatography-tandem mass spectrometry

BACKGROUND

Endocrine disrupting chemicals (EDCs), proved to be potential carcinogenic threats to human health, have received great concerns in food field. It was essential to develop effective methods to detect EDCs in food samples. The present study proposed an efficient method to determine trace EDCs including estrone (E1), 17β-estradiol (E2), estriol (E3) and bisphenol A (BPA) based on magnetic solid-phase extraction (MSPE) coupled high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) in meat samples.

RESULTS

Fe₃ O₄ @COF(TpBD)/TiO₂ nanocomposites were synthesized via functionalization of magnetic covalent organic frameworks (COFs) with titanium dioxide (TiO₂ ) nanoparticles, and used as absorbents of MSPE to enrich EDCs. The efficient EDCs enrichment relies on π-π stacking interaction, hydrogen bonding, and the interaction between titanium ions (IV, Ti⁴⁺ ) and hydroxyl groups in EDCs, which improves the selectivity and sensitivity. Under the optimized conditions, target EDCs were rapidly extracted through MSPE with 5 min. Combining Fe₃ O₄ @COF(TpBD)/TiO₂ based MSPE and HPLC-MS/MS to determine EDCs, good linearities were observed with correlation coefficient (R² ) ≥ 0.9989. The limits of detection (LODs) and limits of quantification (LOQs) were 0.13-0.41 μg kg^-1 and 0.66-1.49 μg kg^-1 , respectively. Moreover, the proposed method was successfully applied to real samples analysis.

CONCLUSIONS

The established MSPE-HPLC-MS/MS method was successfully applied to determine EDCs in meat samples with rapidness, improved selectivity and sensitivity. It shows great prospects for EDCs detection in other complicated matrices. © 2020 Society of Chemical Industry.

Embryonic Exposure to Low Concentrations of Bisphenol A and S Altered Genes Related to Pancreatic β-Cell Development and DNA Methyltransferase in Zebrafish

Bisphenol A (BPA) and bisphenol S (BPS) are implicated in the development of metabolic disorders, such diabetes mellitus. However, the epigenetic mechanism underlying the pancreatic β-cell dysregulation for both BPA/BPS needs clarification. This exploratory study was designed to investigate whether embryonic exposure to low BPA/BPS concentrations impair early pancreatic β-cell differentiation as well as DNA methylation in its gene expression profile using an in vivo model, zebrafish. Zebrafish embryos were exposed to 0, 0.01, 0.03, 0.1, 0.3, and 1.0 µM BPA/BPS at 4-h post fertilization (hpf) until 120 hpf. BPA/BPS-induced effects on pancreatic-related genes, insulin gene, and DNA methylation-associated genes were assessed at developmental stages (24-120 hpf), while glucose level was measure at the 120 hpf. The insulin expression levels decreased at 72-120 hpf for 1.0 µM BPA, while 0.32 and 0.24-fold of insulin expression were elicited by 0.3 and 1 µM BPS respectively at 72 hpf. Significant elevation of glucose levels; 16.3% (for 1.0 µM BPA), 7.20% (for 0.3 µM BPS), and 74.09% (for 1.0 µM BPS) higher than the control groups were observed. In addition, pancreatic-related genes pdx-1, foxa2, ptfla, and isl1 were significantly interfered compared with the untreated group. Moreover, the maintenance methylation gene, dnmt1, was monotonically and significantly decreased at early stage of development following BPA exposure but remained constant for BPS treatment relative to the control group. DNMT3a and DNMT3b orthologs were distinctively altered following BPA/BPS embryonic exposure. Our data indicated that embryonic exposure to low concentration of BPA/BPS can impair the normal expressions of pancreatic-associated genes and DNA methylation pattern of selected genes in zebrafish early development.

Synthesis of magnetic metal organic framework/covalent organic framework hybrid materials as adsorbents for magnetic solid-phase extraction of four endocrine-disrupting chemicals from milk samples

RATIONALE

Endocrine-disrupting chemicals (EDCs), widespread and easily ingested through the simple food chain, have been suggested to pose potential carcinogenic threats to human health. Considering food safety and public health, it is urgent to establish a sensitive and effective method to enrich and determine EDCs in food samples.

METHODS

Novel hybrid nanocomposites Fe₃ O₄ @A-TpBD@NH₂ -MIL-125(Ti) were synthesized through the formation of amide bonds. The as-prepared Fe₃ O₄ were innovatively encapsulated with 4-aminobenzoic acid functionalized COF(A-TpBD) to generate bare carboxyl (-COOH), which formed amide bonds with the NH₂ -MIL-125(Ti), generating well-defined and hierarchical hybrid materials. The Fe₃ O₄ @A-TpBD@NH₂ -MIL-125(Ti) materials were used as the adsorbents for magnetic solid-phase extraction (MSPE) coupled with high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) to enrich and determine EDCs (E1, E2, E3 and BPA) from milk samples.

RESULTS

Fe₃ O₄ @A-TpBD@NH₂ -MIL-125(Ti) exhibited improved adsorption efficiency and selectivity based on π-π stacking interaction, hydrogen bonding, electrostatic interaction, and the interaction between the hydroxyl group in EDCs and titanium ions (IV, [Ti]⁴⁺ ). Under the optimized conditions, Fe₃ O₄ @A-TpBD@NH₂ -MIL-125(Ti)-based MSPE coupled with HPLC/MS/MS showed good linearity with correlation coefficient (R² ) ≥0.9983 and high sensitivity with limits of detection (LODs) in the range of 0.37-0.85 μg/L. Moreover, the developed method was successfully employed to detect EDCs in milk samples.

CONCLUSIONS

Fe₃ O₄ @A-TpBD@NH₂ -MIL-125(Ti) possess good adsorption capability and selectivity for EDCs. In addition, the proposed MSPE-HPLC/MS/MS method based on Fe₃ O₄ @A-TpBD@NH₂ -MIL-125(Ti) is effective and sensitive for the determination of EDCs in real samples, which can be used as a robust alternative method to monitor EDCs in complex matrices.

A sensitive, precise and rapid LC-MS/MS method for determination of ergosterol peroxide in Paecilomyces cicadae mycelium

Ergosterol peroxide (EP) has considerable potential effect against the proliferation of tumor cells. Here, we established a new approach for EP content detection through liquid chromatography-tandem mass spectrometry. The specificity, limit of detection (LOD)/quantitative (LOQ), linearity and range, accuracy, repeatability, and intermediate precision were tested. The EP retention time was 7.18 min. The linear relationship between the mass concentration of nonylphenol and the chromatographic peak area was good within the EP concentration range of 0.1-2.0 μg/mL. The correlation coefficient was 0.994, the regression equation was Y = 27 409.8 × X - 1114.67, the average recovery rate was 82.77%, the relative standard deviation was 11.1%, the LOQ was 50 ng/mL, and the LOD was 20 ng/mL. The detection technique was convenient, accurate, reproducible, and rapid. Therefore, this method could be used for deep liquid fermentation, providing a basis for EP to serve as a quality standard for the fermentation of Paecilomyces cicadae.

Review: Microextraction Technique Based New Trends in Food Analysis

Food chemistry is the study and classification of the quality and origin of foods. The identification of definite biomarkers and the determination of residue contaminants such as toxins, pesticides, metals, human and veterinary drugs, which are a very common source of food-borne diseases. The food analysis is continuously demanding the improvement of more robust, sensitive, highly efficient, and economically beneficial analytical approaches to promise the traceability, safety, and quality of foods in the acquiescence with the consumers and legislation demands. The traditional methods have been used at the starting of the 20th century based on wet chemical methods. Now it existing the powerful analytical techniques used in food analysis and safety. This development has led to substantial enhancements in the analytical accuracy, precision, sensitivity, selectivity, thereby mounting the applied range of food applications. In the present decade, microextraction (micro-scale extraction) pays more attention due to its futures such as low consumption of solvent and sample, throughput analysis easy to operate, greener, robotics, and miniaturization, different adsorbents have been used in the microextraction process with unique nature recognized with wide range applications.

Molecularly Imprinted Polymer Micro- and Nano-Particles. A review

In recent years, molecularly imprinted polymers (MIPs) have become an excellent solution to the selective and sensitive determination of target molecules in complex matrices where other similar and relative structural compounds could coexist. Although MIPs show the inherent properties of the polymers, including stability, robustness, and easy/cheap synthesis, some of their characteristics can be enhanced, or new functionalities can be obtained when nanoparticles are incorporated in their polymeric structure. The great variety of nanoparticles available significantly increase the possibility of finding the adequate design of nanostructured MIP for each analytical problem. Moreover, different structures (i.e., monolithic solids or MIPs micro/nanoparticles) can be produced depending on the used synthesis approach. This review aims to summarize and describe the most recent and innovative strategies since 2015, based on the combination of MIPs with nanoparticles. The role of the nanoparticles in the polymerization, as well as in the imprinting and adsorption efficiency, is also discussed through the review.

Determination of bisphenol A: Old problem, recent creative solutions based on novel materials

Bisphenol A is a synthetic compound widely used in industry, in the production of polycarbonate, epoxy resins, and thermal paper, among others. Its annual production is estimated at millions of tons per year, demonstrating its importance. Despite its wide application in various everyday products, once in the environment (due to its disposal or leaching), it has high toxicity to humans and animal life, and this problem has been well known for years. Given this problem, many researchers seek alternatives for its monitoring in matrices such as natural water, waste, food, and biological matrices. For this, new advanced materials have been developed, characterized, and applied in creative ways for the preparation of samples for the determination of bisphenol A. This article aims to present some of these important and recent applications, describing the use of molecularly imprinted polymers, metal and covalent organic frameworks, ionic liquids and magnetic ionic liquids, and deep eutectic solvents as creative solutions in sample preparation for the long-standing problem of bisphenol A determination.

Aptamer-enhanced fluorescence determination of bisphenol A after magnetic solid-phase extraction using Fe3O4@SiO2@aptamer

Bisphenol A (BPA) is used as a stabilizing agent in many food packaging plastics and is a known endocrine-disrupting chemical that can alter the development of mammary glands, affect egg cells, and cause chromosomal defects. However, the pretreatment of traditional assays for detecting BPA is difficult. In this work, a novel aptamer functionalized magnetic adsorbent was developed and combined with magnetic solid-phase extraction (MSPE) for the selective enrichment of BPA. First, magnetic silica-coated Fe₃O₄ microspheres (Fe₃O₄@SiO₂) were synthesized by the sol-gel method, and functional magnetic nanoparticles (Fe₃O₄@SiO₂@Apt) were formed by modifying with nucleic acids. In the presence of BPA in a MSPE system, the nucleic acid aptamer can specifically capture the target BPA. After magnetic separation, the Apt/BPA composite was eluted, and we observed enhanced fluorescence with the Apt/BPA composite that was formed. Our results showed that this method allowed a limit of detection of 0.05 ng mL^-1.

Magnetic molecularly imprinted electrochemical sensors: A review

The preparation and practical applications of molecularly imprinted electrochemical sensors (MIECSs) remain challenging due to issues involving electrode surface renewal modes, low adsorption capacities, and sample preparation speeds. To solve these issues, magnetic molecularly imprinted electrochemical sensors (MMIECSs) have been extensively explored by various groups. Recently, MMIECSs fabricated based on diverse strategies have yielded insight into the development of MIECSs, and they have provided effective paths for sample preparation, immobilization and renewal of molecularly imprinted polymers (MIPs) on the electrode surface, leading to promising performances of MIECSs. This review comprehensively describes the research advances for various types of MMIECSs and their applications in the fields of food safety, environmental monitoring, and clinical and pharmaceutical analysis. Based on our understanding of MMIECSs, the literature in this field is thoroughly explored and classified in this review. The challenges existing in this research area and some potential strategies for the rational design of high-performance MMIECS are also outlined.