Rapid magnetic-mediated solid-phase extraction and pre-concentration of selected endocrine disrupting chemicals in natural waters by poly(divinylbenzene-co-methacrylic acid) coated Fe3O4 core-shell magnetite microspheres for their liquid chromatography–tandem mass spectrometry determination

Development of a Human Estrogen Receptor Dimerization Assay for the Estrogenic Endocrine-Disrupting Chemicals Using Bioluminescence Resonance Energy Transfer

Endocrine-disrupting chemicals (EDCs) are found in food and various other substances, including pesticides and plastics. EDCs are easily absorbed into the body and have the ability to mimic or block hormone function. The radioligand binding assay based on the estrogen receptors binding affinity is widely used to detect estrogenic EDCs but is limited to radioactive substances and requires specific conditions. As an alternative, we developed a human cell-based dimerization assay for detecting EDC-mediated ER-alpha (ERα) dimerization using bioluminescence resonance energy transfer (BRET). The resultant novel BRET-based on the ERα dimerization assay was used to identify the binding affinity of 17β-estradiol (E2), 17α-estradiol, corticosterone, diethylhexyl phthalate, bisphenol A, and 4-nonylphenol with ERα by measuring the corresponding BRET signals. Consequently, the BRET signals from five chemicals except corticosterone showed a dose-dependent sigmoidal curve for ERα, and these chemicals were suggested as positive chemicals for ERα. In contrast, corticosterone, which induced a BRET signal comparable to that of the vehicle control, was suggested as a negative chemical for ERα. Therefore, these results were consistent with the results of the existing binding assay for ERα and suggested that a novel BRET system can provide information about EDCs-mediated dimerization to ERα.

Analytical Methodology for Trace Determination of Propoxur and Fenitrothion Pesticide Residues by Decanoic Acid Modified Magnetic Nanoparticles

A sensitive, rapid, reliable, and easily applicable method based on magnetic solid phase extraction (MSPE) combined with HPLC-PDA was developed for monitoring propoxur (PRO) and fenitrothion (FEN) pesticides in environmental water samples. The effect of major experimental variables on the extraction efficiency of both the pesticides was investigated and optimized systematically. For this purpose, a new magnetic material containing decanoic acid on the surface of particles was synthesized and characterized by XRD, FT-IR, SEM, EDX, and TGA analysis in detail. The simultaneous determination of pesticide molecules was carried out by using a Luna Omega C18 column, isocratic elution of acetonitrile (ACN): Water (70:30 v/v) with a flow rate of 1.2 mL min^-1. After MSPE, the linear range for pesticide molecules (r² > 0.9982) was obtained in the range of 5-800 and 10-800 ng mL^-1, respectively. The limit of detections (LOD) are 1.43 and 4.71 ng mL^-1 for PRO and FEN, respectively while RSDs % are below 3.5%. The applicability of the proposed method in four different environmental samples were also investigated using a standard addition-recovery procedure. Average recoveries at two spiking levels were over the range of 91.3-102.5% with RSD < 5.0% (n = 3). The obtained results show that decanoic acid grafted magnetic particles in MSPE combined with HPLC-PDA is a fast and simple method for the determination of PRO and FEN in environmental water samples.

Performance of a novel magnetic solid-phase-extraction microsphere and its application in the detection of organic micropollutants in the Huai River, China

Solid phase extraction has been increasingly applied for the detection of organic micropollutants (OMPs). However, time-consuming and high-cost disadvantages also limit the widespread use of this method, especially for the extraction of large-volume field water samples. In this study, a gas chromatography-mass spectrometry (GC-MS) method based on the magnetic microsphere (M150) solid-phase-extraction (MSPE) was established to investigate the OMPs in source water throughout the whole Huai River. In brief, the results demonstrated that the extraction efficiency of the M150 was superior to that of C₁₈ and HLB for the selected OMPs, including species of polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), phthalate esters (PAEs) and nitrobenzenes (NBs), and the method detection limits of M150 for these OMPs were comparable to those of C₁₈ and HLB. The optimized conditions of extraction and elution were the 100 mg/L dosages of microspheres, extraction time of 60 min and pH of 2, and the eluent with a similar polarity, hydrophobicity and molecular structure to the OMPs rendered higher elution efficiencies. A total of 21 types of OMPs affiliating to PAHs, OCPs, PAEs and NBs were detected by the established method, with the total concentrations of 505-2310 ng/L in source water of the Huai River. Spatial differences of the OMPs were also observed, demonstrating the link between pollutant profiles and geographical locations. This study provides an alternative to enrich OMPs in filed water samples, and it reveals pollutant profiles of source water throughout the whole Huai River.

Novel Functionalized Polythiophene-Coated Fe₃O₄ Nanoparticles for Magnetic Solid-Phase Extraction of Phthalates

Poly(phenyl-(4-(6-thiophen-3-yl-hexyloxy)-benzylidene)-amine) (P3TArH) was successfully synthesized and coated on the surface of Fe₃O₄ magnetic nanoparticles (MNPs). The nanocomposites were characterized by Fourier transform infra-red (FTIR), X-ray diffractometry (XRD), Brunauer-Emmett-Teller (BET) surface area analysis, analyzer transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). P3TArH-coated MNPs (MNP@P3TArH) showed higher capabilities for the extraction of commonly-used phthalates and were optimized for the magnetic-solid phase extraction (MSPE) of environmental samples. Separation and determination of the extracted phthalates, namely dimethyl phthalate (DMP), diethyl phthalate (DEP), dipropyl phthalate (DPP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), dicyclohexyl phthalate (DCP), di-ethylhexyl phthalate (DEHP) and di-n-octyl phthalate (DNOP), were conducted by a gas chromatography-flame ionization detector (GC-FID). The best working conditions were as follows; sample at pH 7, 30 min extraction time, ethyl acetate as the elution solvent, 500-µL elution solvent volumes, 10 min desorption time, 10-mg adsorbent dosage, 20-mL sample loading volume and 15 g·L-1 concentration of NaCl. Under the optimized conditions, the analytical performances were determined with a linear range of 0.1⁻50 µg·L-1 and a limit of detection at 0.08⁻0.468 µg·L-1 for all of the analytes studied. The intra-day (n = 7) and inter-day (n = 3) relative standard deviations (RSD%) of three replicates were each demonstrated in the range of 3.7⁻4.9 and 3.0⁻5.0, respectively. The steadiness and reusability studies suggested that the MNP@P3TArH could be used up to five cycles. The proposed method was executed for the analysis of real water samples, namely commercial bottled mineral water and bottled fresh milk, whereby recoveries in the range of 68%⁻101% and RSD% lower than 7.7 were attained.

Molecularly imprinted polymers on multi-walled carbon nanotubes as an efficient absorbent for preconcentration of morphine and its chemiluminometric determination

A simple and selective method was described for the determination of morphine based on its preconcentration by molecularly imprinted polymers on multi-walled carbon nanotubes prior to its chemiluminometric recognition.

Fast determination of 24 steroid hormones in river water using magnetic dispersive solid phase extraction followed by liquid chromatography-tandem mass spectrometry

The easiness-to-handle of the magnetic dispersive solid phase extraction (Mag-dSPE) procedure was developed for preconcentration of 24 steroid hormones in river water. Ethylenediamine-functionalized magnetic carbon nanotubes (EDA@Mag-CNTs) were synthesised by a simple one-pot reaction and were used as sorbent in Mag-dSPE procedure. The properties of the EDA@Mag-CNTs were characterized by transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). An ultra-fast liquid chromatography-tandem quadrupole mass spectrometry (UFLC-MS/MS) method for determination of 24 steroid hormones in river water at nanograms per liter had been developed with pretreatment of the samples by Mag-dSPE. The obtained results demonstrated the higher extraction capacity of EDA@Mag-CNT Mag-dSPE with recoveries between 82.1 and 113%. The limits of quantification (LOQs) for the steroid hormone were between 0.020 and 1.00 ng/L. The developed method had been successfully applied to 60 river water samples, and it was confirmed that EDA@Mag-CNT Mag-dSPE was a highly effective extraction method for the steroid hormone analyses.

Magnetic solid-phase extraction based on modified ferum oxides for enrichment, preconcentration, and isolation of pesticides and selected pollutants

Recently, a simple, rapid, high-efficiency, selective, and sensitive method for isolation, preconcentration, and enrichment of analytes has been developed. This new method of sample handling is based on ferum oxides as magnetic nanoparticles (MNPs) and has been used for magnetic solid-phase extraction (MSPE) of various analytes from various matrices. This review focuses on the applications of modified ferum oxides, especially modified Fe3O4 MNPs, as MSPE adsorbent for pesticide isolation from various matrices. Further perspectives on MSPE based on modified Fe3O4 for inorganic metal ions, organic compounds, and biological species from water samples are also presented. Ferum(III) oxide MNPs (Fe2O3) are also highlighted.

Silane modified magnetic nanoparticles as a novel adsorbent for determination of morphine at trace levels in human hair samples by high-performance liquid chromatography with diode array detection

In this paper we report a novel, sensitive, and rapid method of magnetic solid phase extraction based on surface modified magnetic nanoparticles as a novel nano sorbent for HPLC determination of morphine with diode array detection in human hair samples. Factors affecting the extraction efficiency of the proposed method, including the sample pH, quantity of magnetic nanoparticles, sample volume, desorption solvent type and its volume, and extraction time were investigated and optimized. Under the optimized experimental conditions, a good linearity was observed in the range of 1-800 µgL(-1) for the morphine, with a correlation coefficient (R (2)) of 0.990. The pre-concentration factor of 208.69 was achieved in this method. The detection limit of the method was 0.1 μgL(-1) based on S/N = 3 and good reproducibility with a relative standard deviations lower than (n = 5) 2.59 %. The proposed method has been successfully applied to the analysis of trace amounts of morphine in human hair samples with satisfactory results. This method can be applied in medical toxicology research and forensic medical centers.

Preparation of magnetic chitosan and graphene oxide-functional guanidinium ionic liquid composite for the solid-phase extraction of protein

A series of novel cationic functional hexaalkylguanidinium ionic liquids and anionic functional tetraalkylguanidinium ionic liquids have been synthesized, and then magnetic chitosan graphene oxide (MCGO) composite has been prepared and coated with these functional guanidinium ionic liquids to extract protein by magnetic solid-phase extraction. MCGO-functional guanidinium ionic liquid has been characterized by vibrating sample magnetometer, field emission scanning electron microscopy, X-ray diffraction spectrometer and Fourier transform infrared spectrometer. After extraction, the concentrations of protein were determined by measuring the absorbance at 278 nm using an ultra violet visible spectrophotometer. The advantages of MCGO-functional guanidinium ionic liquid in protein extraction were compared with magnetic chitosan, graphene oxide, MCGO and MCGO-ordinary imidazolium ionic liquid. The proposed method has been applied to extract trypsin, lysozyme, ovalbumin and bovine serum albumin. A comprehensive study of the adsorption conditions such as the concentration of protein, the amount of MCGO-functional guanidinium ionic liquid, the pH, the temperature and the extraction time were also presented. Moreover, the MCGO-functional guanidinium ionic liquid can be easily regenerated, and the extraction capacity was about 94% of the initial one after being used three times.

Evaluation of magnetic nanoparticles to serve as solid-phase extraction sorbents for the determination of endocrine disruptors in milk samples by gas chromatography mass spectrometry

A rapid magnetic solid-phase extraction (MSPE) is proposed based on C18-functionalized magnetic silica nanoparticles as sorbents, for the determination of endocrine disruptors - 20 organochlorine pesticides and 6 polychlorinated biphenyls - in milk samples. Magnetic nanoparticles are characterized by several techniques, such as Scanning Electron Microscopy, X-Ray diffraction, Brunauer-Emmett-Teller and Fourier transform-infrared. The MSPE is performed by dispersion of the Fe3O4@SiO2@C18 nanoparticles in milk samples with sonication, after protein precipitation. Then, the sorbent is collected by applying an external magnetic field and the analytes are desorbed by n-hexane. Several parameters affecting the extraction efficiency of target analytes by the magnetic nanoparticles are investigated, including washing and elution solvents, amount of sorbents, time of extraction and elution, sample and elution solvent volume. The proposed method is optimized by means of experimental design and response surface methodology. When coupled with gas chromatography-mass spectrometry detection and under optimum extraction conditions, average recoveries of target analytes are found to be in the range of 79% to 116%. The proposed MSPE-GC-MS analytical method has a linear calibration curve for all target analytes with coefficients of determination to range from 0.9950 to 0.9999. The limits of quantification are found to be between 0.2 and 1μg/L ensuring compliance with the maximum residue limits established by European Commission and Codex Alimentarius, for OCPs and PCBs residues in milk. The proposed method is applied to the determination of target analytes in milk samples from local markets.

Preparation and characterization of an amphipathic magnetic nanosphere

The amphipathic magnetic nanospheres were synthesized using C8 and polyethylene glycol as ligands. Their morphology, structure, and composition were characterized by transmission electron microscope, Fourier transform infrared, and elementary analysis. The prepared materials presented uniform sphere with size distribution about 200 nm. The magnetic characteristics of magnetic nanomaterials were measured by vibrating sample magnetometer. The target products had a saturation magnetization value of 50 emu g(-1) and superparamagnetism. The adsorption capability was also studied by static tests, and the material was applied to enrich benzenesulfonamide from calf serum. The results exhibited that the C8-PEG phase owned better adsorption capability, biocompatible property, and dispersivity in aqueous samples.

Bifunctional magnetic nanoparticles for analysis of aldehyde metabolites in exhaled breath of lung cancer patients

We report here the preparation of dual-functionalized magnetic nanoparticles, with the nanoparticles as extraction sorbents, a magnetic solid phase extraction method was developed and applied for the analysis of trace amount of aldehydes in human exhaled breath condensate. In the material, octyl-functionalized internal surface provided hydrophobic groups for extraction, non-ionic surfactant (Tween-20)-coated outer surface offered hydrophilic network structure to prevent the access of macromolecules, strong magnetic property of nanoparticles simplified the analytical procedure. The experimental results showed that the prepared nanoparticles exhibited good dispersibility in aqueous solution and excellent extraction efficiency toward aldehydes. Six aldehydes were derivatized with 2,4-dinitrophenylhydrazine and then the formed hydrazones were extracted by the nanoparticles and analyzed by high-performance liquid chromatography-photo diode array detector. Under the optimal conditions, the method provided low limits of detection (2.9-21.5 nmol L(-1)), satisfactory reproducibility (relative standard deviations, 2.9-13.1%) and acceptable recoveries (73.7-133.1%). The developed method was applied successfully to determine the aldehydes metabolites in the exhaled breath condensate samples of healthy people and lung cancer patients. The dual-functionalized material is suitable for biological sample analysis. The proposed method provides an alternative approach for quantification of aldehyde metabolites in complex biological samples.

The use of silica-coated magnetic graphene microspheres as the adsorbent for the extraction of pyrethroid pesticides from orange and lettuce samples followed by GC-MS analysis

Graphene-grafted ferroferric oxide microspheres were used as the adsorbent to extract some pyrethroid pesticides (bifenthrin, λ-cyhalothrin, cyfluthrin, cypermethrin, fenvalerate, and deltamethrin) from orange and lettuce samples prior to their determination by GC-MS. The main variables that could affect the extraction, including the amount of the adsorbent, pH of the sample solution, extraction time, concentration of salt, and desorption conditions, were investigated and optimized. Under the optimized conditions, a linear response was obtained in the concentration range of 0.3-100.0 ng/g for the analytes with the coefficients of determination ranging from 0.9877 to 0.9925. The LODs for the pyrethroids ranged from 0.01 to 0.02 ng/g. The method provided a good repeatability with RSDs < 10.6%. The recoveries for the six pyrethroid pesticides were in the range from 90.0 to 103.7%. The method was applied to the determination of the pesticides in orange and lettuce samples with a satisfactory result.

Application of functionalized magnetic nanoparticles in sample preparation

Functionalized magnetic nanoparticles have attracted much attention in sample preparation because of their excellent performance compared with traditional sample-preparation sorbents. In this review, we describe the application of magnetic nanoparticles functionalized with silica, octadecylsilane, carbon-based material, surfactants, and polymers as adsorbents for separation and preconcentration of analytes from a variety of matrices. Magnetic solid-phase extraction (MSPE) techniques, mainly reported in the last five years, are presented and discussed.

Online in-tube microextractor coupled with UV-Vis spectrophotometer for bisphenol A detection

A simple and high extraction efficiency online in-tube microextractor (ITME) was developed for bisphenol A (BPA) detection in water samples. The ITME was fabricated by a stepwise electrodeposition of polyaniline, polyethylene glycol and polydimethylsiloxane composite (CPANI) inside a silico-steel tube. The obtained ITME coupled with UV-Vis detection at 278 nm was investigated. By this method, the extraction and pre-concentration of BPA in water were carried out in a single step. Under optimum conditions, the system provided a linear dynamic range of 0.1 to 100 μM with a limit of detection of 20 nM (S/N ≥3). A single in-tube microextractor had a good stability of more than 60 consecutive injections for 10.0 μM BPA with a relative standard deviation of less than 4%. Moreover, a good tube-to-tube reproducibility and precision were obtained. The system was applied to detect BPA in water samples from six brands of baby bottles and the results showed good agreement with those obtained from the conventional GC-MS method. Acceptable percentage recoveries from the spiked water samples were obtained, ranging from 83-102% for this new method compared with 73-107% for the GC-MS standard method. This new in-tube CPANI microextractor provided an excellent extraction efficiency and a good reproducibility. In addition, it can also be easily applied for the analysis of other polar organic compounds contaminated in water sample.