Magnetic Solid-phase Extraction Material Research Articles

Sensitive extraction of seven pesticide residues from environmental water with magnetic graphene oxide-based covalent organic framework

The use of pesticides has increased with the development of agriculture. However, due to the trace content and the matrix's inherent complexity in environmental water, development of rapid and sensitive detection method present significant challenges in the analysis of pesticide residues. The study synthesized magnetic graphene oxide (MGO) by combining superparamagnetic nanoparticles with the easy modification of graphene oxide (GO). Covalent organic frameworks (COFs) were then modified to have a large specific surface area. Finally, magnetic graphene oxide-based covalent organic frameworks, namely MGO-COFs, were obtained with a spherical structure and used as magnetic solid-phase extraction materials, which was successfully used to determine the seven pesticide residues in environmental samples in conjunction with high performance liquid chromatography. The method has a wide linear range for the tested pesticides, with satisfactory correlation coefficients (R ≥ 0.099) and low detection limits (0.3–1.21 μg L−1). The correlation coefficients for all seven pesticides were high (R2 ≥ 0.9996). The spiked recoveries, exhibiting a range of 91.3 to 109 %, demonstrated that the developed MGO-COF-MSPE-HPLC-UV method is simple, efficient, and suitable for the analysis and detection of seven pesticide residues in environmental water.

Determination of quinolone antibiotics in surface water by MnFe2O4@TiO2 magnetic solid phase extraction-high performance liquid chromatography

The magnetic solid phase extraction material (MnFe2O4@TiO2) was prepared by coating TiO2 on MnFe2O4 through an in-situ formation method. The structure and properties of MnFe2O4@TiO2 were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), nitrogen adsorption–desorption experiment, and vibrating sample magnetometer (VSM). The conditions for magnetic solid phase extraction (MSPE) of quinolone antibiotics were optimized, and an MSPE-HPLC method was established to determine quinolone antibiotics in water samples. The optimal conditions for MSPE are MnFe2O4@TiO2 amount of 15 mg, extraction time of 15 min, 5 mL of methanol solution with 20 % ammonia as eluent, and elution time of 1 min. Under the optimal conditions, 50 mL 0.1 mg/L mixed standard solutions of fleroxacin, ofloxacin, norfloxacin, ciprofloxacin, and enrofloxacin have achieved enrichment multiples of 67.8, 72.1, 59.6, 55.8, and 60.7, respectively. The linear range of five antibiotics determined by MSPE-HPLC is 0.004–1 mg/L with the relative standard deviations (RSDs) of 2.1 %–4.9 % and the limits of detection (LODs) of 0.0006–0.0020 mg/L. The method is applied to the determination of the five antibiotics in rice paddy water and fish pond water; the recoveries range from 78.9 to 105.8 %, and the RSDs (n = 5) are 3.6 %–8.7 %.

Self-assembled magnetic nanoplatform Fe3O4@SiO2-NH2@Au for magnetic solid-phase extraction of bisphenol A

Developing magnetic adsorbent that combines the merits of quick response, excellent enrichment capacity, uniform and stable dispersivity is of paramount importance in pollutants pretreatment. In this work, tunable strawberry-like Fe3O4 @SiO2-NH2 @Au@ 2-ME magnetic solid phase extraction materials were prepared via assembly method. The obtained nanocomposites were characterized using scanning electron microscopy, X-ray diffraction spectroscopy, infrared spectroscopy, X-ray photoelectron spectroscopy, and whereafter the preparation method was optimized. Integrating magnetic solid-phase extraction with high-performance liquid chromatography and fluorescence detection, a comprehensive enrichment and detection method toward bisphenol A (BPA) was well established. This method demonstrated high efficiency and rapidity, achieving rapid enrichment of BPA. The as-developed method exhibited good linear correlation within the range of 10.0–500 μg·L−1, with a recovery of 85–92%. It showed excellent sensitivity and reproducibility in BPA extraction with low limit of detection (LOD, 0.274 μg·L−1), limit of quantitation (LOQ, 0.913 μg·L−1) and relative standard deviation (RSD, 1.5%, n = 6), respectively. The proposed Fe3O4 @SiO2-NH2 @Au nanoplatform firmly supports the envision that proper surface functionalization of magnetic substrate could promote the enrichment capacity toward various pollutants in actual application scenarios.

A free elution immunoassay for chloramphenicol in chicken and egg after magnetic ZIF-8 adsorption separation

The excellent adsorption and rapid separation capabilities of magnetic MOFs make them desirable pretreatment materials for solid substrates. In this study, magnetic ZIF-8 (mZIF-8) was synthesized in situ by a one-step method in the aqueous solution of magnetic beads. Isothermal adsorption verified that the maximum adsorption capacity of (011) crystal-exposed rhombic dodecahedral ZIF-8 for chloramphenicol was up to 128.31 mg/g (mZIF-8 = 67.18 mg/g). Kinetic adsorption revealed that the type of ZIF-8/mZIF-8 adsorption on chloramphenicol belongs to the pseudo-secondary adsorption kinetics of chemical monomolecular layers. Characterization by FTIR, XPS, and XRD revealed that mZIF-8 interacts with chloramphenicol mainly by π-π electron stacking, electrostatic attraction, and hydrogen bonding interaction. ELISA confirmed that chloramphenicol remained antigenically active after adsorption by mZIF-8. The adsorption and separation of chloramphenicol residues in chicken and egg were completed by mZIF-8 within 20 min. mZIF-8 can be used directly for elution-free ELISA after the adsorption of chloramphenicol. The limits of detection (IC10) of the mZIF-8 + ELISA in chicken and eggs were 1.18 ng/mL and 0.64 ng/mL, respectively. mZIF-8 is expected to be used as a magnetic solid-phase extraction material for the rapid pretreatment of antibiotic residues in other complex solid matrices.

Magnetic solid-phase extraction of bisphenol A from water samples using nanostructured material based on graphene with few layers and cobalt ferrite

In this study, magnetic hybrid materials composed of cobalt ferrite, natural organic matter, and graphene (CoFe2O4/NOM/graphene) were synthesized and applied as adsorbents in the magnetic solid-phase extraction (MSPE) of bisphenol A (BPA) from aqueous matrices. To our knowledge, no studies have been previously conducted using this material for MSPE. Techniques including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and transmission electron microscopy (TEM) were used to investigate the composition and morphology of the adsorbent. The MSPE method was optimized considering the main parameters influencing the process, with the best results obtained using 50.0 mg of adsorbent, agitation at 150 rpm, total extraction time of 7.5 min, 10 mL of methanol as extractant, and pH between 4 and 10. BPA analysis was performed using HPLC-DAD and HPLC-FL, with the latter showing better sensitivity. The developed method provided a wide linear range from 0.1 to 5000 μg L−1, with limits of detection (LOD) and quantification (LOQ) of 0.022 and 0.072 μg L−1, respectively. The extraction procedure presented reproducibility (RSD) of 2.13–2.21% and excellent recoveries in the range 99.3–104%. The developed MSPE method using CoFe2O4/NOM/graphene proved to be simple, fast, and efficient for the analysis of BPA in a variety of aqueous matrices.

3DG Functionalized Magnetic Solid Phase Extraction Materials for the Efficient Enrichment of Hexamethylenetetramine in Vermicelli.

Solid phase extraction (SPE) is regarded as the most effective purification method for complex matrix samples owing to its simplicity of operator, time-saving, high accuracy, and environmental friendliness. SPE technology is still affected by the high cost of commercial SPE columns and poor adsorption selectivity. Hence, the development of low-cost and highly selective adsorbents is quite challenging and demanding in SPE. In this study, a novel 3DG functionalized magnetic solid phase extraction materials was prepared based on “thiol-ene” click chemistry. The structure, morphology, thermal stability, and magnetic properties of the magnetic composites were studied by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). Then the adsorption performance of composite was determined by static adsorption experiments, which showed fast binding kinetics (100 min) and good adsorption performance (Qe = 65.34 mg/g). Moreover, these magnetic nanoparticles were used as adsorbents for magnetic solid phase extraction (MSPE) and coupled with high-performance liquid chromatography (HPLC) for separation and detection of illegally added hexamethylenetetramine in vermicelli. As for practical application, the recoveries for the spiked samples in the concentration range of 8–40 μg/g were between 83.24–92.69%, and the RSD was between 0.20–2.07%.

Magnetic solid phase extraction based on Fe3O4@SiO2@CTS nano adsorbent for the sensitive detection of trace polychlorinated biphenyls in environmental water samples

In this study, a magnetic composite material was developed by bonding the modified natural polysaccharide chitosan (CTS) with SiO2 on the surface of magnetic Fe3O4 nanoparticles to detect polychlorinated biphenyls (PCBs). The structural, porosity, and magnetic properties of Fe3O4@SiO2@CTS were characterized by scanning electron microscopy, infrared spectroscopy, X-ray diffraction, nitrogen sorption, and vibrating sample magnetometry. Various experimental parameters affecting the extraction capacity were investigated, including extraction time, desorption time, desorption solvent, solution pH value, and salt ion concentration. Results showed that Fe3O4@SiO2@CTS exhibited excellent selectivity, easy separation by magnet, and reusability (at least 10 cycles). Under optimized experimental condition, this magnetic solid phase extraction material was applied to detect three PCBs with low limits of detection of 0.02–0.15 μg·L−1. The linear correlation coefficient was higher than 0.998, while the recoveries ranged between 90.34% and 106.99% with the relative standard deviation less than 11.31%. The practical application of Fe3O4@SiO2@CTS was verified through quantitative analysis of PCB residues in environmental water, supporting its promising role in simple, convenient, and low-cost detection of PCBs in real environmental samples.

Preparation of a ZIF-67-modified magnetic solid phase extraction material and its application in the detection of pyridine ring insecticides

An advanced and reliable m-SPE material of a water-stable ZIF was developed for the determination of trace praziquantel and pymetrozine in spinach and broccoli.

Preparation of coal-derived magnetic carbon material for magnetic solid-phase extraction of fungicides from water samples

A magnetic solid-phase extraction method has been developed for the extraction and analysis of some fungicides in environmental water samples. Azoxystrobin, chlorothalonil, cyprodinil and trifloxystrobin were the target fungicides selected. First, a carbon material was obtained from the raw coal sample collected from Zonguldak region by ash removal process and then a magnetic C/Fe3O4 composite was produced from the carbon material using a single-step thermal method. The magnetic C/Fe3O4 composite was characterized by N2 adsorption-desorption, X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. This composite was then used as an adsorbent for the magnetic solid-phase extraction of fungicides from water samples followed by high-performance liquid chromatographic analysis. Experimental parameters affecting the extraction efficiency such as adsorbent amount, type and volume of desorption solvent, adsorption and desorption time, ionic strength, and pH were optimized. Under the optimized conditions, the extraction efficiency for azoxystrobin, chlorothalonil, cyprodinil and trifloxystrobin was found to be 71%, 44%, 41% and 70%, respectively. The method detection limits for fungicides were found to be in the range of 0.4-1.1 µg L-1. The relative standard deviations were found to be lower than 6.6% and 6.9% for intra-day and inter-day precisions, respectively. The extraction of related fungicides from water samples collected from Zonguldak region was carried out efficiently. The recoveries obtained from spiked water samples were in the range of 71–106%.

Commercially available color-catching sheets for magnetic textile solid phase extraction of water-soluble dyes

Magnetic textile solid phase extraction, based on the use of magnetically separable color-catching sheets, was successfully employed for the preconcentration of water-soluble dyes methylene blue and crystal violet from water solutions. The photos of color-catching sheet squares with the adsorbed dye were taken with a mobile phone. The computer-based image analysis of the photos was performed using ImageJ freeware while smartphone-based image analysis employed On Color Measure application. The values of saturation from HSB (hue – saturation – brightness) color space, as well as red channel values from RGB (red – green – blue) color space were proportional to the methylene blue and crystal violet concentration in the analyzed samples. This novel method has a potential to be a useful semiquantitative determination procedure for dye analysis.

Magnetic Textile Solid Phase Extraction of Cationic Dyes from Water Solutions

Magnetically responsive acrylic nonwoven textile impregnated with negatively charged κ-carrageenan was used as an adsorbent for the extraction of cationic dyes using magnetic textile solid phase extraction (MTSPE). Polysaccharide modified textile squares were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy; both techniques confirmed successful modification of textile fibers. The extracted dyes were analyzed by spectrophotometry of the dyes eluted at low pH and by image analysis of the dyed textile. Dyes in the concentration range 0.1–2 mg/l were successfully analyzed. It was clearly shown that MTSPE is an efficient preconcentration procedure for dye analysis.

TiO2 nanoparticles and C-Nanofibers modified magnetic Fe3O4 nanospheres (TiO2@Fe3O4@C–NF): A multifunctional hybrid material for magnetic solid-phase extraction of ibuprofen and photocatalytic degradation of drug molecules and azo dye

Accurate sensitive analysis of drug ingredient substances in biological, pharmaceutical and environmental samples and removal of drug ingredient substances in environmental samples owngreat importance for sustaining viability. The realization of these processes using a single material offers significant advantages in terms of cost, time and ease of use. In this study, TiO2 nanoparticles and C-Nanofibers modified magnetic Fe3O4 nanospheres (TiO2@Fe3O4@C-NFs) synthesized as a multifunctional material employing a simple hydrothermal synthesis method. This innovative material was exploited in the magnetic solid-phase extraction (MSPE) method for the preconcentration of ibuprofen and photocatalytic degradation of antibiotics, non-steroidal anti-inflammatory drugs (NSAIDs), and azo dye. To our knowledge, no studies have been previously conducted using the same material as magnetic solid-phase extraction adsorbent and magnetically separable photocatalyst. The characterization of TiO2@Fe3O4@C-NFs was carried out by XRD, FE-SEM, EDX and Raman techniques. The main analytical parameters affecting MSPE performance of ibuprofen such as pH, sorbent amount eluent type and volume and sample volume were optimized. The optimum values of the method were determined at the following parameters: pH 4.0, adsorbent amount 150 mg and eluent 2 mL of acetone. Ibuprofen analysis after MSPE was carried out using a high-performance liquid chromatography diode array detection system (HPLC-DAD). The photocatalytic degradation efficiencies of TiO2@Fe3O4@C–NF hybrid material for probe-analytes reached 80–100% and the complete degradation attained within the range of 8–125 min under UV irradiation. Simple preparation, practical isolation from solutions, high efficiency, reproducibility, and sustainability are the main advantages of the TiO2@Fe3O4@C-NFs for MSPE and photocatalytic degradation applications.

Net-like mesoporous carbon nanocomposites for magnetic solid-phase extraction of sulfonamides prior to their quantitation by UPLC-HRMS.

A net-like mesoporous carbon nanocomposite (MCN) was hydrothermally prepared by using filter paper as the raw material. The MCN contains magnetic nanoparticles of type Fe3O4 which result from the addition of Fe(NO3)3·9H2O during synthesis. The MCN was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, Raman spectra, Brunauer-Emmett-Teller methods and vibrating sample magnetometry. The MCN is shown to be a viable material for magnetic solid-phase extraction of trace sulfonamides (SAs) including sulfadiazine, sulfapyridine, sulfamerazine, sulfamethazine, sulfamethizole, sulfamethoxypridazine, sulfachloropyridazine and sulfadimethoxine. Following desorption with acetone containing 0.5% ammonia, the SAs were quantified by UPLCwith high-resolution mass spectrometric detection. With sulfamethazine as an example, the adsorption equilibrium configurations and the major interaction mechanism between SAs and the MCN were calculated by using density functional theory. Under the optimal conditions, the calibration plots are linear in the 0.05-10ng·mL-1 SA concentration ranges. The limits of detection are between 7.2 and 13.6ng·L-1. The recoveries from spiked samples ranged from 79 to 107%, with relative standard deviations of <9.9%. Graphical abstractSchematic representation of nanocomposite preparation, adsorption mechanism of sulfonamide and magnetic solid-phase extraction (MSPE) for sulfadiazine (SDZ), sulfapyridine (SPD), sulfamerazine (SMR), sulfamethazine (SMZ), sulfamethizole (SMT), sulfamethoxypridazine (SMP), sulfachloropyridazine (SCP) and sulfadimethoxine (SDMX).Quantificationwas accomplished by UPLC with high-resolution mass spectrometric detection.

Smartphone-based image analysis for evaluation of magnetic textile solid phase extraction of colored compounds

Novel modern easily feasible methods for direct evaluation of a new, simple preconcentration analytical procedure have been developed. Two types of smartphone image analysis applications (ON Color Measure and Color Lab) were evaluated to obtain RGB and HSV color spaces data for the quantification of Magnetic textile solid phase extraction of colored compounds (e.g. water-soluble organic dyes). Both direct measurement of color spaces values via the smartphone camera and image analysis of the photograph can be used successfully. The obtained data were similar to those obtained by previously examined professional ImageJ software. The saturation (S) values of the HSV color space are directly proportional to the concentrations of the analyzed dye.

Textile bound methyltrioctylammonium thiosalicylate ionic liquid for magnetic textile solid phase extraction of copper ions

Textile modified with methyltrioctylammonium thiosalicylate ionic liquid was successfully used for Magnetic textile solid phase extraction of copper ions. After extraction process the modified textile changed color to gray and black. The textile photos were employed for image analysis using HSB and RGB color spaces. It was shown that values of saturation (S) and red channel values (R) were proportional to the copper ions concentration in the analyzed samples; the value of saturation was almost linearly proportional to copper ions concentration in the range 10−3 – 10−5 mol L−1. This inexpensive, simple and elution free assay has a potential to be a useful alternative to existing semiquantitative determination procedures for copper ions analysis.

Magnetically responsive materials for solid phase extraction

Magnetically responsive materials have found many important applications in analytical chemistry. In this short review the basic information about Magnetic solid phase extraction and Magnetic textile solid phase extraction is given. These analytical techniques enable to preconcentrate target biologically active compounds or pollutants from water samples. Both procedures enable to lower the limit of detection using conventional analytical procedures.

Trace analysis of quercetin in tea samples by HPLC-DAD system by means of a new nanocomposite including magnetic core-shell

ABSTRACT A new magnetic core-shell multiwalled carbon nanotube@nanodiamond nanocomposite was synthesized, characterized and used as magnetic solid-phase extraction material. The usability of material was checked on the separation and pre-concentration of quercetin in tea samples by magnetic solid-phase extraction and high-performance liquid chromatography with diode array detector system. There was a linear relationship between chromatographic area and concentration of quercetin in the range of 5.0–600 ng mL−1. The limit of detection and quantification limits were 1.46 and 4.91 ng mL−1, respectively. The developed method has been applied to determine quercetin at trace levels in tea samples.

Magnetically responsive textile for preconcentration of acid food dyes

Chitosan impregnated, polyacrylonitrile nonwoven textile formed from micrometer sized fibres (diameter 15 μm), was used for a newly developed analytical procedure named Magnetic Textile Solid Phase Extraction (MTSPE). This procedure was applied for fast preconcentration of synthetic acid food dyes from water solutions followed by their elution at high pH and subsequent spectrophotometric determination. The proposed method was applied for extraction of tartrazine, azorubine (carmoisine) and indigo carmine from water solutions with the dye content up to 200 μg/L. MTSPE was efficiently used in volumes up to 2 L.

Magnetic Graphene Solid-Phase Extraction for the Determination of 47 Kinds of Non-steroidal Anti-inflammatory Drug Residues in Animal Food with Liquid Chromatography Tandem Mass Spectrometry

Based on magnetic graphene (Fe3O4-G), a liquid chromatography with tandem mass spectrometric detection (LC-MS/MS) method coupled with magnetic solid-phase extraction was developed for the simultaneous detection of 47 kinds of nonsteroidal anti-inflammatory drug (NSAID) residues in meat of swine, chicken, and bovine. The samples were extracted with acetonitrile-phosphate, then the extracts were purified by dispersed solid-phase extraction based on magnetic graphene (Fe3O4-G). The linearity range is 0.1–50 μg L−1. Limits of detection were between 0.1 μg kg−1 and 0.5 μg kg−1, and limits of quantification were between 0.5 μg kg−1 and 1.0 μg kg−1. The average recoveries were 72.4–97.1% at spiking levels. The inter-day RSDs varied from 5.3 to 12.6%. Due to the advantages of easy collection of magnetic solid-phase extraction materials, the method was more rapid and efficient for the enrichment and separation without filling columns. The sensitivity, precision, and accuracy method was suitable for simultaneous detection of multi-component residues of nonsteroidal anti-inflammatory drugs.

Semiquantitative determination of food acid dyes by magnetic textile solid phase extraction followed by image analysis

Magnetic textile solid phase extraction, based on the use of magnetically modified non-woven textile impregnated with chitosan, was successfully employed for the preconcentration of acid food dyes from water solutions. The photos of textile squares with the adsorbed dye were taken with a mobile phone. The image analysis of the photos was performed using appropriate freeware. The values of saturation, obtained through the HSB color space, were proportional to the dye concentration in the analyzed samples. Described inexpensive, simple and elution free assay enables analysis of dyes concentration in various solutions. This novel method has a potential to be a useful alternative to existing semiquantitative determination procedures, especially for dyes analysis.