Effective Magnetic Solid-phase Extraction Research Articles

Enrichment and detection of polycyclic aromatic hydrocarbon in tea and coffee using phenyl-functionalized NiFe2O4@Ti3C2TX based magnetic solid-phase extraction

Polycyclic aromatic hydrocarbons (PAHs) are commonly found in various environmental matrices and have received significant attention due to their toxic effects on ecosystems and environmental health. In this study, a specific magnetic composite material derived from MXene, known as phenyl-functionalized NiFe2O4@Ti3C2TX, was designed and synthesized using a simple method. This composite material was used to develop an effective magnetic solid-phase extraction (MSPE) method for enriching trace polycyclic aromatic hydrocarbons (PAHs) in tea and coffee samples. The eluted PAHs were analyzed via gas chromatography–tandem mass spectrometry. Under optimal conditions, this method exhibited excellent linear relationships for 16 PAHs within the ranges of 0.001–25 and 0.0005–25 μg/L, with correlation coefficients exceeding 0.9979. The limits of detection for the target PAHs ranged from 0.1 to 0.3 ng/L. The effectiveness of the proposed method was evaluated by analyzing tea and coffee samples, and the satisfactory spiked recoveries of PAHs ranged from 84.5% to 112.6%.

Fabrication of sea urchin shaped polyaniline-modified magnetic microporous organic network for efficient extraction of non-steroidal anti-inflammatory drugs from animal-derived food samples

In this work, a novel polyaniline-modified magnetic microporous organic network (MMON-PANI) composite was fabricated for effective magnetic solid phase extraction (MSPE) of five typical nonsteroidal anti-inflammatory drugs (NSAIDs) from animal-derived food samples before high performance liquid chromatography (HPLC) detection. The core-shell sea urchin shaped MMON-PANI integrates the merits of Fe3O4, MON, and PANI, exhibiting large specific surface area, rapid magnetic responsiveness, good stability, and multiple binding sites to NSAIDs. Convenient and effective extraction of trace NSAIDs from chicken, beef and pork samples is realized on MMON-PANI via the synergetic π-π, hydrogen bonding, hydrophobic, and electrostatic interactions. Under optimal conditions, the MMON-PANI-MSPE-HPLC-UV method exhibits wide linear ranges (0.2–1000 μg L−1), low limits of detection (0.07–1.7 μg L−1), good precisions (intraday and inter-day RSDs < 5.4 %, n = 3), large enrichment factors (98.6–99.9), and less adsorbent consumption (3 mg). The extraction mechanism and selectivity of MMON-PANI are also evaluated in detail. This work proves the incorporation of PANI onto MMON is an efficient way to promote NSAIDs enrichment and provides a new strategy to synthesize multifunctional MON-based composites in sample pretreatment.

Ordered mesoporous graphitic carbon nitride/cobalt ferrite composite for highly effective magnetic solid-phase extraction of bisphenols in lake and tap water samples

Development of sensitive monitoring method for environmental contaminants is of great interest in both environmental science and analytical chemistry. Here we report the facile hydrothermal fabrication of ordered mesoporous graphitic carbon nitride/cobalt ferrite composite (MCN/CoFe2O4) with large surface area and adequate magnetic property. The prepared MCN/CoFe2O4 was developed as an adsorbent for magnetic solid-phase extraction for bisphenols (bisphenol F, bisphenol A and bisphenol AF) prior to HPLC coupled with variable wavelength detector. The factors influencing the extraction procedure, adsorption kinetics, isotherms and thermodynamics were investigated in detail. The extraction performed with 20 mg of MCN/CoFe2O4 sorbent in 15 mL of sample solution was accomplished within only 15 min and gave the enrichment factors of 123.6–154.6. Meanwhile, the adsorption process followed the pseudo-second-order kinetic and Freundlich models. Under the optimized conditions, the method provided the limits of detection (S/N = 3) and limits of quantification (S/N = 10) of 0.15–0.25 μg/L and 0.50–0.90 μg/L, and the recoveries of 80.5%−104.0%. Moreover, the adsorbent was stable enough after 16 adsorption-desorption cycles. The developed approach not only presented an alternative strategy for sensitive and rapid determination of bisphenols in environmental water samples, but also promoted the synthesis and application of MCN in the field of sample pretreatment.

Magnetic solid-phase extraction of organophosphorus pesticides from apple juice and environmental water samples using magnetic graphene oxide coated with poly(2-aminoterephthalic acid-co-aniline) nanocomposite as a sorbent.

An effective magnetic solid-phase extraction method was proposed using magnetic graphene oxide coated with poly(2-aminoterephthalic acid-co-aniline) as a sorbent for preconcentration and extraction of organophosphorus pesticides from environmental water and apple juice samples, and determined using the gas chromatography-mass spectrometry analysis. To approve the successful synthesis of the magnetic nanocomposite, the prepared sorbent was characterized by field emission scanning electron microscopy, X-ray diffraction, vibrating sample magnetometer, and Fourier transforms infrared techniques. The main parameters affecting the extraction efficiency were considered and studied to afford an optimized procedure. Systematic method validation verified its suitable recoveries (89.4-107.3%), and precision (relative standard deviations<6.8%). The method showed a wide linear dynamic range (0.04-700ng/mL) with low limits of detection (0.01-0.06ng/mL) and quantification (0.04-0.21ng/mL). This method presented good potential and great sensitivity for the pesticides determination.

Pre-Concentration and Determination of Tetracyclines Antibiotics Residues in Water Samples Using RGO/Fe&lt;sub&gt;3&lt;/sub&gt;O&lt;sub&gt;4&lt;/sub&gt; Nanocomposite as Extraction Sorbent

Existing methods used in tracing Tetracyclines' antibiotics (TCAs) residues which pose serious environmental problems, consume high amounts of organic solvents, are time-consuming, and are relatively expensive. A simple and effective magnetic solid-phase extraction (MSPE) based on reduced graphene oxide/magnetite (RGO/Fe3O4) nanocomposite sorbent was successfully developed for preconcentration and extraction of TCAs residues from water samples. The analytes were determined by high-performance liquid chromatography with a diode-array detector (HPLC-DAD). The synthesized nanocomposite was characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), and field emission scanning electron microscopy (FESEM). Sample pH, amount of adsorbent, sample volume, extraction time, desorption time, and desorption solvent were evaluated and optimized. Under optimized conditions, the method demonstrated good linearity over the concentration range of 0.05–1.0 mg L–1 with the coefficient of determination (R2) ≥ 0.9978. Limit of detection (LOD) and limit of quantification (LOQ) were 0.006–0.011 mg L–1 and 0.019–0.036 mg L–1, respectively. The accuracy and precision of the developed method were proven by good analyte recovery (89.77–106.33%) and acceptable precision with relative standard deviation, RSD ≤ 5.54%. The results showed that magnetic solid RGO/Fe3O4 could be a suitable adsorbent in the preconcentration and extraction of TCAs in water samples.

Novel Fe3O4@metal-organic framework@polymer core-shell-shell nanospheres for fast extraction and specific preconcentration of nine organophosphorus pesticides from complex matrices

Herein, a novel core-shell-shell magnetic nanosphere denoted as Fe3O4@ZIF-8@polymer was fabricated by sequential in situ self-assembly and precipitation polymerization for effective magnetic solid-phase extraction of nine organophosphorus pesticides (OPPs) from river water, pear, and cabbage samples. The integrated Fe3O4@ZIF-8@polymer featured convenient magnetic separation property and excellent multi-target binding ability. More importantly, the functional polymer coating greatly improved the extraction performance of Fe3O4@ZIF-8 for OPPs, thus facilitating the simultaneous determination of trace OPP residues in real samples. The developed MPSE-LC-MS/MS method exhibited good linearity (R2 ≥ 0.9991) over the concentration range of 0.2–200 µg L−1, low limits of detection of 0.0002–0.005 μg L−1 for river water and 0.006–0.185 μg kg−1 for pear and cabbage, satisfactory precision with relative standard deviations ≤ 9.7% and accuracy with recoveries of 69.5–94.3%. These results highlight that the combination of polymers with MOFs has great potential to fabricate excellent adsorbents for high-throughput analysis of various contaminants in complex matrices.

Tannic acid-directed synthesis of magnetic and boronic acid-functionalized metal-organic frameworks for selective extraction and quantification of catecholamines in human urine.

Anovel magnetic borate-functionalized metal-organic framework nanocomposite was designed and fabricated for selective enrichment of catecholamines from human urine. Firstly, the polytannic acid (PTA) layer with natural low-cost and ecofriendly polyphenol tannic acid as the organic ligand and Fe3+ as the cross-linker was coated onto the surface of Fe3O4. Then, the borate-functionalized metal-organic framework (MIL-100(Fe)-B) with 5-boronobenzene-1,3-dicarboxylic acid as a ligand fragment was modified onto the PTA-coated Fe3O4 through a metal-ligand-fragment coassembly strategy. The obtained smart porous adsorbent Fe3O4@PTA@MIL-100(Fe)-B was confirmed by means of several characterization methods and then applied as an effective magnetic solid phase extraction (MSPE) sorbent for specific extraction of trace catecholamines in human urine. The Plackett-Burman design was used for screening the variables significantly affecting the extraction efficiency. Then, the significant factors were further investigated by the Box-Behnken design to determine the optimal extraction conditions. Under the optimal conditions, a method for selective MSPE combined with high-performance liquid chromatography with a fluorescence detector for the quantitation of catecholamines in human urine was developed and validated. With the proposed method, the linearity range was from 0.500 to 500ngmL-1 for norepinephrine and epinephrine and from 1.00 to 500ngmL-1 for dopamine. The detection limits were 0.050, 0.11, and 0.20ngmL-1 for norepinephrine, epinephrine, and dopamine, respectively. The recoveries from spiking experiments varied from 91.5 to 108% with relative standard deviations (RSDs) of 0.80-4.8%. The established method israpid, sensitive, accurate, inexpensive, and ecofriendly and was successfully applied to the determination of the target catecholamines in human urine samples.

Fabrication of polyethyleneimine modified magnetic microporous organic network nanosphere for efficient enrichment of non-steroidal anti-inflammatory drugs from wastewater samples prior to HPLC-UV analysis

Development of novel functionalized adsorbents for efficient magnetic solid phase extraction (MSPE) is essential for promoting their versatile applications in sample pretreatment. Herein, we report the fabrication of a new polyethyleneimine-600 decorated magnetic microporous organic network nanosphere (Fe3O4@MON-PEI600) for effective MSPE of trace non-steroidal anti-inflammatory drugs (NSAIDs) from different water samples. The core-shelled Fe3O4@MON-PEI600 integrates the synergistic effects of Fe3O4, MON and PEI600, providing facile and effective extraction to NSAIDs via multiple hydrogen bonding, π-π and hydrophobic interactions. The inner MON shell employs π-π and hydrophobic interaction sites and the outer PEI-600 coat acts as the hydrogen bonding doner/receptor, which affords good extraction performance for NSAIDs. Under optimal conditions, the Fe3O4@MON-PEI600-MSPE-HPLC-UV method gives wide linear range (0.14–400 μg L−1), low limits of detection (0.042–0.149 μg L−1), good precisions (intra-day and inter-day RSDs < 4.5%, n = 6), and large enrichment factors (97.0–98.2). Extraction mechanisms and selectivity of Fe3O4@MON-PEI600 are evaluated in detail. Moreover, Fe3O4@MON-PEI600 is successfully applied to enrich the trace NSAIDs in different water samples with the concentrations of 0.7 and 0.8 μg L−1 for 1-naphthylacetic acid, 0.5 and 0.1 μg L−1 for naproxen as well as 0.7 μg L−1 for ibuprofen, respectively. The developed method not only affords a novel and efficient magnetic adsorbent for NSAIDs in aqueous media at trace level, but also provides a new strategy for the rational design and synthesis of multiple functionalized MON composites in sample pretreatment.

Magnetic polyamidoamine dendrimer grafted with 4-mercaptobenzoic acid as an adsorbent for preconcentration and sensitive determination of polycyclic aromatic hydrocarbons from environmental water samples

Polyamidoamine dendrimer decorated Fe3O4 magnetic nanoparticles was synthesized and grafted with 4-mercaptobenzoic acid (4-MBA). The resulting material was utilized to develop an effective magnetic solid phase extraction method in combination with high performance liquid chromatography for trace determination of polycyclic aromatic hydrocarbons including phenanthrene (PHE), anthracene (ANT), fluoranthene (FLT), pyrene (PYR) and benzo(a)pyrene (BaP). The MNPs@G3.0@4-MBA exhibited to be an efficient extracting medium due to the existence of terminal benzene ring groups, the internal pores, and strong hydrophobic interactions and π-π interactions. The experiments demonstrated that the proposed method possessed excellent linearity in the concentration range of 0.1–300 μg L−1 with correlation coefficients (R) larger than 0.997, and the limits of detection (LODs, S/N = 3) according to the ratio of signal to noise equal to three of PHE, ANT, FLT, PYR and BaP were 0.014 μg L−1, 0.032 μg L−1, 0.055 μg L−1, 0.027 μg L−1 and 0.039 μg L−1, respectively. The proposed method was applied to real water samples and the spiked recoveries were over the range of 92–99%. The results showed that the method earned good repeatability and high sensitivity, and the as-prepared materials were stable and reusable, which displayed that the proposed method would have a wonderful application prospect.

Core-shell structured magnetic covalent organic frameworks for magnetic solid-phase extraction of diphenylamine and its analogs.

Core-shell structured magnetic covalent organic frameworks (Fe3O4@COFs) were synthesized via a facile approach at room temperature using 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 2,5-dibromo-1,4-benzenedicarboxaldehyde (DBDA) as two building blocks for the first time. The Fe3O4@COFs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), nitrogen adsorption-desorption isotherms, and zeta potentiometric analysis. The Fe3O4@COFs had a high specific surface area (141.94 m2·g-1) and uniform pore size distribution (average 4.53nm). They also demonstrated good magnetic response (32.49 emu·g-1) and good thermal and chemical stabilities. Furthermore, adsorption experiments were conducted to evaluate the adsorption capacities and adsorption times of Fe3O4@COFs to diphenylamine (DPA) and its analogs, including benzidine (BZ), 1-naphthylamine (1-NA), 4-phenylphenol (4-PP), and O-tolidine (O-TD). From the experimental results, the maximum adsorption capacities of DPA, 1-NA, 4-PP, BZ, and O-TD were calculated as 246.25, 95.20, 85.85, 107.20, and 123.55 mg·g-1, respectively. A duration of 20min was sufficient for adsorption. The Fe3O4@COFs were explored as adsorbents for magnetic solid-phase extraction (MSPE) of DPA and its analogs, and the MSPE parameters, including adsorbent dosage, extraction time, pH, ionic strength, desorption solvent, desorption time, and desorption frequency were optimized. Combined with HPLC using diode-array detection, a simple, fast, and sensitive method was proposed to detect DPA and its analogs, which exhibited good linearity (r >0.9946) in the range of 0.1-100 μg·mL-1. Moreover, the low limits of detection (ranging from 0.02 to 0.08 μg·mL-1, S/N=3), low limits of quantitation (ranging from 0.05 to 0.30 μg·mL-1, S/N=10), good precision with low relative SDs (<5.86% for intra-day and <6.44% for inter-day) were obtained. Finally, Fe3O4@COFs were applied to the effective MSPE of DPA and its analogs in actual samples chosen from the natural environment, and good recoveries (ranging from 79.97 to 122.52%) were observed.

Magnetic Solid-Phase Extraction of Pyrethroid Pesticides from Environmental Water Samples Using Deep Eutectic Solvent-type Surfactant Modified Magnetic Zeolitic Imidazolate Framework-8.

A simple, sensitive and effective magnetic solid-phase extraction (MSPE) technique was developed for the extraction of pyrethroid pesticides from environmental water samples, followed by gas chromatography tandem triple quadrupole mass spectrometry determination. An adsorbent of magnetic zeolitic imidazolate framework-8@deep eutectic solvent (M-ZIF-8@DES) was prepared using deep eutectic solvent coated on the surface of M-ZIF-8. The features of M-ZIF-8@DES were confirmed by material characterizations, and the results indicated that M-ZIF-8@DES has a good magnetism (61.3 emu g−1), a decent surface area (96.83 m2 g−1) and pore volume (0.292 mL g−1). Single factor experiments were carried out to investigate the effect of different conditions on the performance of MSPE. Under the optimal conditions, the developed method performs good linearity (R2 ≥ 0.9916) in the concentration range of 1–500 μg L−1. The limits of detection were in the range of 0.05–0.21 μg L−1 (signal/noise = 3/1). The intraday relative standard deviation (RSD) and interday RSD were less than 9.40%. Finally, the proposed technique was applied for the determination of pyrethroid pesticides in environmental water samples. This work shows the potential of DES-modified metal-organic frameworks for different sample pretreatment techniques.

Magnetic Solid-Phase Extraction of Dichlorodiphenyltrichloroethane and Its Metabolites from Environmental Water Samples Using Ionic Liquid Modified Magnetic Multiwalled Carbon Nanotube/Zeolitic Imidazolate Framework-8 as Sorbent.

As persistent organic pollutants, dichlorodiphenyltrichloroethanes (DDTs) and their metabolites pose considerable risks to human health and the environment. Therefore, monitoring DDTs in the environment is essential. Here, we developed a green, simple, and effective magnetic solid-phase extraction (MSPE) method coupled with gas chromatography tandem triple-quadrupole mass spectrometry to determine the DDT content of environmental water samples. A magnetic ionic liquid (IL) adsorbent was developed based on a modified magnetic multiwalled carbon nanotube/zeolitic imidazolate framework-8 (MM/ZIF-8/IL), synthesized by immobilizing the IL on the surface of MM/ZIF-8. We confirmed successful synthesis of MM/ZIF-8/IL by material characterization, and our results suggested that the MM/ZIF-8/IL had a high Brunauer–Emmett–Teller surface area (159.9 m2 g−1), good thermostability (<800 °C), and a high degree of superparamagnetism (52.9 emu g−1). Several experimental conditions affecting the MSPE efficiency were optimized. Under the best conditions, good detection linearity was achieved (0.5–500 µg L−1) with determination coefficients ranging from 0.9927 to 0.9971. The lower limits of detection (0.0016–0.0072 µg L−1) also had good precision, having an intraday relative standard deviation (RSD) ≤ 6.5% and an interday RSD ≤ 8.9%. Finally, we used the as-developed method to determine DDT levels in environmental water samples.

A high efficient adsorbent for plant growth regulators based on ionic liquid and β-cyclodextrin functionalized magnetic graphene oxide

Four types of ionic liquids which composed of cation with imidazole ring and anion with benzene, naphthalene, anthraquinone and naphthoquinone ring were prepared and named VOIm+BenSO3-, VOIm+NapSO3-, VOIm+AQSO3- and VOIm+NQSO3-, respectively. Then, ionic liquids and β-cyclodextrin functionalized magnetic graphene oxide materials were firstly synthesized for the extraction of 23 plant growth regulators in vegetable samples. The synthesized materials anticipated the unique properties of ionic liquids, β-cyclodextrin, graphene oxide and Fe3O4@SiO2, including high surface area, high supramolecular recognition capability, superparamagnetism and large delocalized π-electron system, which were successfully characterized. Among four kinds of ionic liquids functionalized adsorbents, the VOIm+AQSO3- modified material exhibited high adsorption capability to 7 plant growth regulators compared with Fe3O4@SiO2/GO/β-CD, Fe3O4@SiO2/GO and other three types of ionic liquids based adsorbents. Parameters that could affect the recoveries of 7 plant growth regulators were investigated, such as mass ratio of Fe3O4@SiO2/GO/β-CD to ionic liquids, salt concentration, pH, amount of adsorbent, extraction time and desorption solvent. Under the optimal condition, the magnetic solid phase extraction method using VOIm+AQSO3- and β-cyclodextrin functionalized magnetic graphene oxide material (Fe3O4@SiO2/GO/β-CD/IL) as adsorbent was developed and coupled with ultra-high performance liquid chromatography-triple quadrupole linear ion trap mass spectrometry for the determination of 7 plant growth regulators in vegetable samples. Validation results showed that the limit of detection and limit of quantitation were in the range of 0.01–0.18 μg/kg and 0.03–0.58 μg/kg, respectively. The satisfactory linearities were acquired in the concentration of 2–50 μg/kg with the correlation coefficients higher than 0.9982. Taken together, the synthesized Fe3O4@SiO2/GO/β-CD/IL was a highly effective magnetic solid phase extraction adsorbent for the enrichment of trace level of plant growth regulators in vegetable samples.

Facile synthesis of boronic acid-functionalized magnetic metal-organic frameworks for selective extraction and quantification of catecholamines in rat plasma.

Precise determination of the endogenous catecholamines, dopamine (DA), epinephrine (E) and norepinephrine (NE) faces substantial challenges due to their low physiological concentrations in plasma. We synthesized, for the first time, a magnetic metal–organic framework (MIL-100) composite with boronic acid-functionalized pore-walls (denoted as MG@MIL-100-B composite) using a metal–ligand-fragment coassembly (MLFC) strategy. The composites were then applied as an effective magnetic solid-phase extraction (SPE) sorbent for determination of trace catecholamine concentrations in rat plasma through coupling with HPLC-MS/MS. The obtained nano-composites exhibited high magnetic responsivity, uniform mesopores, large specific surface area, and boronic acid-functionalized inner pore-walls. Catecholamines in rat plasma were extracted through interaction between the cis-diol structures and the boronic acid groups in the MG@MIL-100-B composites. Extraction conditions were optimized by studying SPE parameters including adsorption and desorption time, elution solvent type, pH conditions and adsorbent amount. With our approach, the detection limits (S/N = 3) were as low as 0.005 ng mL−1 for DA and E, and 0.02 ng mL−1 for NE. Intra- and inter-day precision ranged from 2.84–6.63% (n = 6) and 5.70–11.44% (n = 6), respectively. Recoveries from spiking experiments also showed satisfactory results of 94.40–109.51%. Finally, the MG@MIL-100-B composites were applied successfully to determine catecholamine concentrations in rat plasma.

Quantification of mycotoxins in vegetable oil by UPLC-MS/MS after magnetic solid-phase extraction

ABSTRACTThe detection of mycotoxin contamination in foodstuffs is highly significant for public health. Herein we report an analytical method based on magnetic solid-phase extraction (MSPE) and UPLC-MS/MS for the simultaneous determination of mycotoxins, including fumonisins B1 (FB1), zearalenone (ZON) and ochratoxin A (OTA), in vegetable oil. Magnetic nanoparticles coated with double layers of silicon dioxide were synthesised and found to be an effective MSPE adsorbent for mycotoxins. The proposed MSPE procedure serves not only for sample clean-up but also for mycotoxin enrichment that enhances greatly the assay’s sensitivity. Under the selected MSPE conditions, linear matrix-matched calibration curves were obtained for mycotoxins in a concentration range from 0.178 to 625 μg kg–1. The limits of detection were 0.210 μg kg–1 for FB1, 0.0800 μg kg–1 for OTA and 1.03 μg kg–1 for ZON. The proposed MSPE UPLC-MS/MS method was applied for the determination of mycotoxins in vegetable oil samples, including maize oil, rapeseed oil and soybean oil. ZON was detected in a maize oil at 101 μg kg–1, which is below the European Union limit of 200 μg kg–1 in foodstuffs.

Magnetic cobalt-nitrogen-doped carbon microspheres for the preconcentration of phthalate esters from beverage and milk samples

The authors describe the preparation of magnetic cobalt/nitrogen-doped carbon microspheres (Co-N/Cs) by combining a hydrothermal procedure with a carbonization process. The textures of the Co-N/Cs were investigated by powder X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, nitrogen adsorption-desorption isotherms and vibration sample magnetometry. The Co-N/Cs possess a high surface area and strong magnetism. This results in good adsorption capability and enables magnetic separation. The Co-N/Cs are shown to be an effective magnetic solid-phase extraction adsorbent for the enrichment of various phthalate esters (diethyl phthalate, diallyl phthalate and diisobutyl phthalate) from sport beverages and milk samples prior to their determination by HPLC. The limits of detection (at an S/N ratio of 3) are between 0.1–0.2 and 0.08–0.3 ng mL−1 for sport beverages and milk samples, respectively. The recoveries when extracting all the spiked samples varied from 80.3% to 116.2%.

Occurrence investigation of perfluorinated compounds in surface water from East Lake (Wuhan, China) upon rapid and selective magnetic solid-phase extraction.

Using a novel magnetic nanocomposite as adsorbent, a convenient and effective magnetic solid-phase extraction (MSPE) procedure was established for selective separation and concentration of nine perfluorinated compounds (PFCs) in surface water sample. Then an ultra high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) system was employed for detection of PFCs. Good linearity of the developed analytical method was in the range of 0.5–100 ng L−1 with R2 > 0.9917, and the limits of detection (LODs) ranged from 0.029 to 0.099 ng L−1. At three fortified concentrations of 0.5, 5 and 50 ng L−1, the spiked recoveries of PFCs were in the range of 90.05–106.67% with RSDs < 12.62% (n = 3). The proposed analytical method was applied for determination of PFCs in surface water from East Lake (Wuhan, China). The total concentrations of nine PFCs ranged from 30.12 to 125.35 ng L−1, with perfluorooctane sulfonate and perfluoroctanoic acid as the most prevalent PFCs, and the greatest concentrations of PFCs were observed in Niuchao lakelet. The concentrations of the PFCs (C ≥ 11) were mostly less than the limits of quantification (LOQs), attributed to the possibility that the more hydrophobic long-chain PFCs are potential to accumulate in sediment and aquatic biota.

Planar graphene oxide-based magnetic ionic liquid nanomaterial for extraction of chlorophenols from environmental water samples coupled with liquid chromatography–tandem mass spectrometry

A planar graphene oxide-based magnetic ionic liquid nanomaterial (PGO-MILN) was synthesized. The prepared PGO-MILN was characterized by transmission electronmicroscopy (TEM) and Fourier-transform infrared spectrometry (FTIR). The results of adsorption experiments showed that the PGO-MILN had great adsorption capacity for 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP) and pentachlorophenol (PCP). Based on the adsorption experimental data, a sensitive magnetic method for determination of the five CPs in environmental water samples was developed by an effective magnetic solid-phase extraction (MSPE) procedure coupled with high-performance liquid chromatography–tandem mass spectrometry (LC–MS/MS). The effects of main MSPE parameters including the solution pH, extraction time, desorption time, and volume of desorption solution on the extraction efficiencies had been investigated in detail. The recoveries ranged from 85.3 to 99.3% with correlation coefficients (r) higher than 0.9994 and the linear ranges were between 10 and 500ngL−1. The limits of detection (LODs) and limits of quantification (LOQs) of the five CPs ranged from 0.2 to 2.6ngL−1 and 0.6 to 8.7ngL−1, respectively. The intra- and inter- day relative standard deviations (RSDs) were in the range from 0.6% to 7.4% and from 0.7% to 8.4%, respectively. It was confirmed that the PGO-MILN was a kind of highly effective MSPE materials used for enrichment of trace CPs in the environmental water.

Graphene Oxide-Based Magnetic Solid Phase Extraction Combined with High Performance Liquid Chromatography for Determination of Patulin in Apple Juice

Magnetic solid phase extraction (MSPE) is a valuable tool for the extraction and preconcentration of analytes from environmental, food, and biological samples because of its convenience, promptness, and simplicity. In this study, a graphene oxide-based magnetic nanocomposite (MGO) was synthesized and characterized by various instrumental methods. An effective MSPE procedure coupled with high-performance liquid chromatography (MSPE-HPLC) was developed for the preconcentration and determination of the patulin (PAT) in apple juice samples. Critical experimental parameters of MSPE that could affect the extraction efficiencies, such as the amount of MGO, the pH, and ionic strength of the sample solution; the extraction time; and the desorption conditions, were investigated. After optimizing the conditions, the detection limit of this method provided was 2.3 μg/kg; the recoveries were in the range of 68.7–83.6 %, with relative standard deviations (RSDs) ranging between 1.8–8.7 %. It was confirmed that the graphene-based magnetic nanocomposite was a kind of effective MSPE material used for the PAT analyses in apple juice samples.

Rapid Determination of Trace Sulfonamides in Milk by Graphene Oxide-Based Magnetic Solid Phase Extraction Coupled with HPLC–MS/MS

A simple and rapid method based on magnetic solid-phase extraction (MSPE) combined with high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (HPLC–MS/MS) was used for the determination of 15 sulfonamides from milk samples. The extraction and cleanup used a graphene oxide-based magnetic nanocomposite (Fe3O4@GO) as an adsorbent. Various experimental parameters that could affect the extraction efficiencies, such as the amount of Fe3O4@GO, the extraction time, the ionic strength of sample solution, and the type of eluent, were investigated. Under optimized experimental conditions, good linearity was observed in the range of 2.0 to 100.0 μg L−1 for all of the analytes, with correlation coefficients (R2) ranging from 0.994 to 0.999. The limits of detection for the method ranged between 0.02 and 0.13 μg L−1. Mean values of the relative standard deviation of intraday and interday precision ranging from 1.0 to 7.3 % and from 1.7 to 8.1 % were obtained, respectively. The average recoveries were between 73.4 and 97.4 % at three different spiked levels. It was confirmed that the Fe3O4@GO nanocomposite was an effective MSPE material for use in sulfonamide analyses in milk samples.