Simple Magnetic Solid-phase Extraction Research Articles

Facile construction of a stable core-shell spherically magnetic polyimide covalent organic framework for efficient extraction of phenylurea herbicides

Efficient enrichment is crucial for the highly sensitive monitoring of phenylurea herbicides (PUHs) in various environmental waters. In this work, a stable core-shell spherically magnetic polyimide covalent organic framework (COF) was synthesized via a simple template-mediated precipitation polymerization method under mild conditions using tri(4-aminophenyl)amine (TAPA) and 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) as the building units (denoted as Fe3O4@TAPA-BPDA). The Fe3O4@TAPA-BPDA exhibits remarkable adsorption performance for PUHs with an optimized adsorption time of only 10 min. The adsorption of PUHs by Fe3O4@TAPA-BPDA followed the pseudo-second-order kinetic model and the Langmuir model. Furthermore, hydrogen bonding, halogen bonding, hydrophobic interaction, electro donor-acceptor interaction and π-π interactions are identified as the dominant mechanisms contributing to excellent adsorption performance. It was demonstrated that halogen bonds play an important role in the adsorption of substances containing chlorine atoms. The Fe3O4@TAPA-BPDA is easy to operate and highly regenerable. A simple magnetic solid-phase extraction (MSPE) method based on the Fe3O4@TAPA-BPDA was then developed for the rapid extraction of five PUHs in real samples, coupled with high-performance liquid chromatography (HPLC) determination. The analytical method developed has a linear range of 0.5–50 ng/mL, and the limit of detection (LOD) ranges from 0.06 to 0.10 ng/mL. The method exhibits good accuracy with recoveries ranged from 74.5 % to 111.4 %. The analytical method was successfully applied to the highly sensitive detection of PUHs in environmental water samples, which highlighting the potential application of the Fe3O4@TAPA-BPDA in the sample pretreatment.

Tractable Method for Rapid Quality Assessment of Therapeutic Antibodies in Harvested Cell Culture Fluid based on FcγRIIIa-Immobilized Magnetic Microspheres.

FcγRIIIa-binding affinity is one of the key factors to ensure the efficacy of many antitumor therapeutic antibodies, which should be monitored along with the titer, protein aggregation, and other critical quality attributes. The conventional workflow for the quality assessment of therapeutic antibodies in harvested cell culture fluid (HCCF) is time-consuming and costly nevertheless. In this study, a tractable method was established for rapid quality assessment of a HCCF sample through differentially extracting IgG with different FcγRIIIa affinity levels using FcγRIIIa-immobilized magnetic microspheres, followed by size exclusion chromatography (SEC) to determine the amount and monomer percentage of IgGs in the preceding eluate. FcγRIIIa-immobilized magnetic microspheres with polydopamine (PDA) and hydrophilic dendrimer (PAMAM) coating (denoted as Fe3O4@PDA@PAMAM-FcγRIIIa) were synthesized for the first time as magnetic adsorbents. The PDA cladding endowed the composites with good chemical stability in acidic elution buffer, and the PAMAM dendrimer empowered the composites of high ligand immobilization capacity and hydrophilic surface. The labile FcγRIIIa was immobilized under mild conditions. By directly applying a simple magnetic solid phase extraction procedure to treat HCCF, favored IgG species with high FcγRIIIa affinity would be selectively captured by Fe3O4@PDA@PAMAM-FcγRIIIa composites for subsequent SEC analysis. The monomer peak area value in SEC, which was set as the read-out of the proposed method, correlated directly with the theoretical overall quality of standard-spiked HCCF samples.

Determination of fipronil and its metabolites in egg samples by UHPLC coupled with Q-Exactive high resolution mass spectrometry after magnetic solid-phase extraction

A novel, rapid and simple magnetic solid-phase extraction (MSPE) method combined with ultra-high performance liquid chromatography coupled with Q-Exactive high resolution mass spectrometry (UHPLC-Q-Exactive HRMS) was proposed for determination of fipronil and its metabolites in egg samples. In this study, novel polydopamine functionalized magnetic core-shell mesoporous silica nanoparticles (Fe3O4@nSiO2@mSiO2-PDA) were used as MSPE adsorbent for purification and enrichment of fipronil and its metabolites for the first time. The proposed method showed a good linearity (R2 ≥ 0.997), high sensitivity (limit of detection in the range of 0.002–0.004 μg/kg and limit of quantification in the range of 0.006–0.010 μg/kg), adequate recovery (80.6–95.3%) and repeatability (intra-day precision in the range of 2.2–6.7% and inter-day precision in the range of 4.4–10.7%). Finally, the developed MSPE-UHPLC-Q-Exactive HRMS method was successfully applied for determination of fipronil and its metabolites in egg samples.

Rapid and Simple Magnetic Solid Phase Extraction of Bisphenol A from Bottled Water, Baby Bottle, and Urine Samples Using Green Magnetic Hydroxyapatite/β-Cyclodextrin Polymer Nanocomposite

Rapid and Simple Magnetic Solid Phase Extraction of Bisphenol A from Bottled Water, Baby Bottle, and Urine Samples Using Green Magnetic Hydroxyapatite/β-Cyclodextrin Polymer Nanocomposite

Fabrication of functionalized magnetic microspheres based on monodispersed polystyrene for quantitation of allyl-benzodioxoles coupled with gas chromatography and mass spectrometry

Monodispersed magnetic microspheres were synthesized by the magnetization of the aminized polystyrene cores and the subsequent polymerization of allyl glycidyl ether, divinylbenzene and N-vinyl-2-pyrrolidone, which exhibited excellent monodispersity in aqueous solution and high efficiency for allyl-benzodioxoles extraction. Various techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR) and vibrating sample magnetometry (VSM) were employed to characterize the composites. Coupled with gas chromatography-mass spectrometry (GC–MS), a sensitive and simple magnetic solid phase extraction (MSPE) procedure based on the prepared microspheres was established for determination of allyl-benzodioxoles in cola-flavoured drinks. The factors affecting the extraction procedure, such as pH value, adsorbent amount, adsorption time, desorption solution and desorption time were optimized. The developed method was characterized by a high recovery (spiked at 5 μg L−1, 25 μg L−1 and 250 μg L−1), a low detection limit (0.05 μg L−1 for safrole and 0.08 μg L−1 for myristicin), a good linearity (correlation coefficients higher than 0.9990 for both) and a satisfactory repeatability (relative standard deviation below 3.7% for both, n = 3). The approach proposed here was confirmed to be fast and reliable for quantitative analysis of allyl-benzodioxoles in cola samples, especially at a trace level.

Extraction of ultratrace amounts of nelfinavir from biological samples and pharmaceutical formulations using surfactant-modified magnetite nanoparticles followed by spectrophotometric determination

A new sensitive, selective, rapid, and simple magnetic solid phase extraction (MSPE)/spectrophotometry method was proposed for extraction and determination of nelfinavir in biological samples and pharmaceutical formulations using tetradecyltrimethylammonium bromide (TTAB)-coated Fe3O4 nanoparticles (Fe3O4 NPs) as an efficient adsorbent. The synthesized Fe3O4 NPs were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Fourier transform infrared (FT-IR) spectrometry was used for confirmation of TTAB-coated Fe3O4 NPs. The influence of various parameters affecting the extraction of nelfinavir has been investigated. The maximum extraction efficiency for extraction of 100.0μg nelfinavir from aqueous solution was obtained with 18.6mg Fe3O4 NPs and 9mg TTAB at pH=9. The analyte was desorbed by 2.5mL acetonitrile (AN) prior to the absorbance measurement. Under optimized conditions, quantitative extraction recoveries of nelfinavir were observed with the sample volumes up to 600mL and hence an enrichment factor of 240 was obtained. This method was so rapid and complete recovery was obtained in 5s. By applying this method for determination of nelfinavir in sample volume of 600mL, the calibration curve was linear in the range of 15.4–500μgL−1 (r2=0.994) and the detection limit was obtained 0.83μgL−1. Also, the relative standard deviations (RSD) for determination of 100.0 and 300.0μgL−1 of nelfinavir were 1.20% and 2.4% (n=7), respectively. This method was successfully applied for determination of nelfinavir in serum samples, urine samples, and pharmaceutical formulations. The recoveries of spiked serum and urine samples were between 98.7% and 102.4%. All the obtained results are indicative of a convenient, fast, and economic method for extraction and determination of nelfinavir from biological samples and pharmaceutical formulations.

Preconcentration and determination of ranitidine hydrochloride in real samples by using modified magnetic iron oxide nanoparticles

This method shows a novel, fast, and simple magnetic solid-phase extraction (SPE) and spectrophotometric procedure for preconcentration and determination of ranitidine hydrochloride in human plasma and aquatic samples by using Fe3O4 nanoparticles (NPs) modified by sodium dodecyl sulfate (SDS) as an extractor. The unique properties of Fe3O4 NPs including high surface area and strong magnetism were utilized effectively in the magnetic SPE process. The determination method is based on the SDS-coated Fe3O4 NPs with extracted ranitidine-HCl, which was subsequently monitored spectrophotometrically at λmax = 320 nm. Effects of different parameters influencing the extraction efficiency of ranitidine-HCl including the pH value, amount of SDS, and Fe3O4 NPs, extraction time, desorption solvent, desorption time, and sample volume were optimized. Under optimized conditions, the method was successfully applied to the extraction of ranitidine-HCl from human plasma and aquatic samples. The extraction recovery in human plasma and different matrixes of waters were investigated and values of 89.0%–103.4% were obtained. The calibration graph for the determination of ranitidine-HCl was linear in the range of 0.025–1.50 μg mL−1 with R2 = 0.9946. The limit of detection of the proposed method was 7.5 × 10−3 μg mL−1. The repeatability and reproducibility (relative standard deviation) of the mentioned method were 0.83% and 1.22%, respectively. The experimental results showed that the proposed method was feasible for the analysis of ranitidine-HCl in environmental and biological samples.

Synthesis of g-C3N4/Fe3O4 nanocomposites and application as a new sorbent for solid phase extraction of polycyclic aromatic hydrocarbons in water samples

An easy preparation of g-C3N4/Fe3O4 nanocomposites by chemical co-precipitation has been demonstrated. The as-prepared materials were characterized by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. The high affinity of g-C3N4 toward polycyclic aromatic hydrocarbons and the magnetic behavior of Fe3O4 were combined to provide an efficient and simple magnetic solid phase extraction (MSPE). The adsorption and desorption of polycyclic aromatic hydrocarbons on g-C3N4/Fe3O4 were examined. Different factors affecting the magnetic solid phase extraction of polycyclic aromatic hydrocarbons were assessed in terms of adsorption, desorption, and recovery. Under the optimized conditions, the proposed method showed good limits of detection (LOD, S/N=3) in the range of 0.05–0.1ngmL−1 and precision in the range of 1.8–5.3% (RSDs, n=3). This method was also successfully applied to the analysis of real water samples; good spiked recoveries over the range of 80.0–99.8% were obtained.

Preconcentration of trace amounts of lead in water samples with cetyltrimethylammonium bromide coated magnetite nanoparticles and its determination by flame atomic absorption spectrometry

A sensitive and simple magnetic solid phase extraction procedure was presented for the preconcentration of lead ions in environmental water samples. In the present study, lead ions form complexes with 1-(2-pyridilazo)-2-naphthol reagent (PAN) in basic medium, and then are quantitatively extracted to the surface of cetyltrimethylammonium bromide (CTAB)-coated magnetite nanoparticles (Fe3O4 NPs). After magnetic separation of adsorbent, the adsorbent was eluted with 0.5% (v/v) HCl in methanol prior to its analysis by flame atomic absorption spectrometry (FAAS). The pH of sample, concentrations of PAN, amounts of CTAB and Fe3O4 NPs, sample volume and desorption conditions were optimized. Under optimum conditions, the calibration curve was linear in the range of 0.05–100ngmL−1 with R2=0.9996. Detection and quantification limits of the proposed method were 0.005 and 0.05ngmL−1, respectively. Enhancement factor of 1050 was achieved using this method to extract 1000mL of different environmental water samples. Compared with conventional solid phase extraction methods, the advantages of this method still include easy preparation of sorbents, short times of sample pre-treatment, high extraction yield, and high breakthrough volume. It shows great analytical potential in preconcentration of lead from large volume water samples.