Amount Of Fe3O4 Nanoparticles Research Articles

Structural, electrical and magnetoresistance feature of PP+Fe3O4 + Multi-walled carbon nanotubes nano-hybrid based polymer nanocomposite

This work studied the role of the iron oxide and MWCNT in a change of the electrophysical properties of PP + Fe3O4 + MWCNT nanocomposite to evaluate the potential of these nanocomposites as magnetic field sensors and EMI materials. The morphology of the obtained nanocomposites was studied with a scanning electron microscope and investigated that the sizes of both magnetite nanoparticles and carbon nanotubes stay stable during the three-phase nanocomposite formation. In addition, the X-ray diffraction method revealed that MWCNT plays an essential role in the ordered structure-formation of a polymer nanocomposite more than iron oxide nanoparticles. Dielectric properties of the PP + Fe3O4 nanocomposite were studied. Both dielectric permeability and dielectric losses of PP+MWCNT+Fe3O4 nanocomposites were enhanced. The dielectric permeability of the nanocomposite increased due to the interphase polarization, which in turn related to the formation of ordered structure caused the partial arrangement of carbon nanotubes in the polymer. Furthermore, the study showed that the negative magnetoresistance effect of PP+MWCNT+Fe3O4 nanocomposites is more dependent on the amount of Fe3O4 nanoparticles than that of MWCNT, which explained by the spin polarization of Fe3O4 nanoparticles at room temperature. In this research, the PP+5%Fe3O4+1%MWCNT nanocomposites were considered to be an effective material for magnetic field sensors and EMI shielding.

Multiplex Aptamer-Based Fluorescence Assay Using Magnetism-Encoded Nanoparticles for Simultaneous Detection of Multiple Pathogenic Bacteria.

Multiplex assay has emerged as a robust and versatile method for the simultaneous detection of multiple analytes in a single test. However, challenges in terms of poor accuracy and complexity remained. In this work, we developed a multiplex aptamer-based fluorescence assay using magnetism-encoded nanoparticles for the simultaneous detection of multiple pathogenic bacteria. The encapsulation of different amounts of Fe3O4 nanoparticles in zeolitic imidazolate framework-90 (ZIF-90) leads to the formation of Fe3O4@ZIF-90 (FZ) composites with distinct magnetism strengths. By functionalizing a specific aptamer on the surface of the FZ composites, target bacteria can be specifically and precisely separated from a mixed sample in a sequential manner. This property allows for the simultaneous quantitative analysis of multiple target bacteria by using a single-color fluorescence label, thereby resulting in minimal spectral crosstalk interference and improved accuracy. The successful determination of multiple bacteria in contaminated milk samples demonstrates the applicability of this multiplex assay in complex biological matrices. Compared to conventional multiplex fluorescence assays, this approach offers distinct advantages of simplicity, efficiency, and implementation. We believe that this study can provide valuable insights into the development of the multiplex assay while introducing a new method for the simultaneous detection of multiple bacteria.

In-situ aligning magnetic nanoparticles in thermoplastic adhesives for contactless rapid joining of composite structures

Magnetic nanoparticles of high magnetic susceptibility, such as magnetite (Fe3O4), have been used for wireless heating of adhesives and composites through the magnetic hysteresis loss mechanism, but the high concentrations of nanoparticles needed to meet heating performance targets can degrade mechanical properties. Herein, we present an in-situ aligning method to enhance the heating efficiency of magnetite nanoparticles in a nylon thermoplastic matrix without adversely affecting its mechanical strength. A composite adhesive was made by dispersing Fe3O4 nanoparticles in a nylon matrix followed by hot melting. Experimental results show that by subjecting the adhesive to an alternating magnetic field during the hot-melt process, its heating rate can be improved by 200% compared to that without applying the magnetic field. The improvement in the heating performance has been identified to stem from the alignment of the ease axis of the magnetic nanoparticles. This in-situ aligning technique enables better induction heating performance with the same amount of Fe3O4 nanoparticles, avoiding the agglomeration problem of high nanoparticle concentrations. Moreover, this technique makes it possible to develop high-performance self-heating thermoplastic adhesive for reversible bonding and self-healing solution with a wide range of applications, such as bonding and debonding of composites, temporary attachment of systems, and recyclable bonded structures.

Fe3O4-Nanoparticle-Modified Sensor for the Detection of Dopamine, Uric Acid and Ascorbic Acid

A simple electrochemical sensor based on electrochemically synthesized Fe3O4 nanoparticles was constructed by an ink with the nanoparticles, isopropanol, NAFION and carbon Vulcan to detect dopamine, uric acid and ascorbic acid. The electrocatalytic activity of the nanoparticles for the oxidation of the analyte molecules was examined by means of cyclic voltammetry and square wave voltammetry. The parameters controlling the performance of the sensor were optimized, such as the amount of Fe3O4 nanoparticles (1, 2, 3, 5, 8, 10 mg), amount of binder (5, 10, 15 µL) and carbon Vulcan in the ink (4, 6, 8 mg). The temperature was maintained at 25 °C and the pH was 7.5 with buffer phosphate. The optimal sensor conditions were 8 mg magnetite, 4 mg carbon Vulcan and 5 µL of NAFION@ 117. The calibration curves for the three analytes were determined separately, obtaining linear ranges of 10–100, 20–160 and 1050–2300 µM and limits of detection of 4.5, 14 and 95 µM for dopamine, uric acid and ascorbic acid, respectively. This electrochemical sensor has also shown significant sensitivity and selectivity without interference from the three analyte molecules presented simultaneously in solution. This sensor was applied for the detection of these molecules in real samples.

Enhanced thermal diffusion in the vertical direction of flexible polyimide composite films with magnetically alignable h-BN platelets via ferrofluids hybridization

A facile approach is proposed to improve the anisotropic heat conduction of polyimide composite films containing hexagonal boron nitride (h-BN), thermally conductive filler with high anisotropy, via surface hybridization with ferrofluids as magnetic carrier source. The surfaces of the h-BNs were decorated with Fe3O4 particles to control their alignment using magnetic field. The h-BNs with hydroxyl groups (f-BN) were mixed with ferrofluids and heated to 130 °C with stirring. A considerable amount of Fe3O4 nanoparticles was attached to the surface of f-BNs, named mf-BNs. Flexible polyimide (PI) composite films were prepared by adding mf-BNs at 1–30 wt.% to investigate the anisotropic alignment of mf-BNs under magnetic field. The thru-plane thermal conductivity of the PI composite film with vertically aligned mf-BN of 30 wt.% is 6 times higher than that of the neat PI film, as increased from 0.212 to 1.246 W/m∙K. This result is attributed to the anisotropic h-BN particles coated with the magnetic fluid arranged within the PI matrix in the vertical direction by using a neodymium magnet with less than 150 mT. This can solve the thermal issues of next-generation electronics by speeding the vertical heat transfer, which can greatly contribute to the improvement of the device reliability.

Electromagnetic Shielding Effectiveness of Glass Fiber/Epoxy Laminated Composites with Multi-Scale Reinforcements

In this study, an experimental investigation has been performed to understand the electromagnetic interference-shielding effectiveness (EMI-SE) of glass fiber/epoxy laminated composites embedded with carbon nanotubes (CNTs) and Fe3O4 nanoparticles, reinforced with micro carbon fibers along the thickness direction. Micro carbon fibers were reinforced along the thickness direction between the laminates using an electro-flocking process and a vacuum infusion process used to fabricate the composites. The EMI-SE of the composites was measured in the X-band frequency range (8–12 GHz). The effect of carbon fibers of three different lengths (80 µm, 150 µm, and 350 µm) with two different fiber densities (1000 and 2000 fibers/mm2) and two different amounts of Fe3O4 nanoparticles (0.5 and 1 wt.%) on total SE, absorption, and reflection was investigated. Due to the synergetic effect of Fe3O4 nanoparticles, CNTs, and carbon fibers, the final EMI shielding of the composites was mainly dominated by the absorption process. The absorption was more pronounced in the composites of longer carbon fibers with improved electrical conductivity. The presence of Fe3O4 nanoparticles also enhanced total SE values with improved magnetic permeability. The composite with micro carbon fibers of 350 µm length and 2000 fibers/mm2 density with 1 wt.% of Fe3O4 nanoparticles showed the maximum value of total SE.

Contactless magnetic nanoparticle detection platform based on non-linear GMI effect

A detection platform based on non-linear Giant Magnetoimpedance Effect was analyzed for the design of a contactless and low-cost detector of magnetic nanoparticles. The sensor consists of two soft magnetic amorphous wires (Co66Fe2Si13B15Cr4, 1.5 cm in length) placed in parallel and connected electrically in series. Initially, a simple voltage divider was employed to characterize the variations of the first, V1fand second harmonic, V2f, voltages. Their response was analyzed under the effect of the remnant magnetic field generated by different amounts of Fe3O4 nanoparticles (mean diameter 140 nm) as a function of an external magnetic field, H. Due to the larger relative variations showed by V2f, the second harmonic was chosen for the final prototype development. An electronic interface was designed for both current excitation and V2f detection. The designed detection platform, characterized by high detection sensitivity, low-cost, portable, and reusable features, can be employed to efficiently detect magnetic nanoparticles.

Ultra-small Fe3O4 nanoparticles encapsulated in hollow porous carbon nanocapsules for high performance supercapacitors

A new nanoscale architecture of Fe3O4-carbon hybrid materials was developed by a vacuum incipient wetness procedure. The amount of Fe3O4 nanoparticles were controllably confined inside the cavity of the bowl-shaped hollow porous carbon nanocapsules (CNB). TEM images and TG curves proved that different loading of Fe3O4 small nanoparticles (NPs) with a diameter less than 50 nm were stored in CNB. Benefiting from the synergistic effect of the appropriate amount of uniformly dispersed Fe3O4 NPs and bowl-shaped carbon nano-capsules with high specific surface area, high conductivity and high amount of Nitrogen (N) and oxygen (O) elemental doping of Fe3O4@CNB, the new architecture provides good reversibility for the transport of electrolyte ions. When tested in supercapacitor devices, Fe3O4@CNB-2 (containing 40.3 wt% Fe3O4) exhibited the highest gravimetric (466 F g−1) and volumetric capacitance (624 F cm−3). The supercapacitors based on these materials also showed excellent cycling stability (92.4% capacitance retention after 5000 cycles). This class of Fe3O4-carbon hybrid materials has excellent electrochemical properties, and its synthesis strategy can be extended to construct other hybrid materials for various applications, such as biomedicine, catalysis, energy harvest, energy storage and so on.

Fe3O4 nanoparticles as matrix solid-phase dispersion extraction adsorbents for the analysis of thirty pesticides in vegetables by ultrahigh-performance liquid chromatography-tandem mass spectrometry

Herein we report the first example of Fe3O4 nanoparticles (FNPs) being used as single-matrix solid-phase dispersion (MSPD) adsorbents for the extraction of 30 representative pesticides from vegetables. This study was aimed at analyzing the extracted samples using ultrahigh-performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS). Various condition parameters, such as the eluent, volume of the eluent, and amount of FNPs were optimized to achieve good sensitivity and precision for the elution and extraction of the analytes. The developed method was validated using matrices consisting of eight vegetables (lettuce, cucumber, carrot, tomato, pepper, shallot, Chinese flowering cabbage, and cabbage) spiked with 30 pesticides at concentrations of 0.01, 0.1, and 1.0 mg/kg. The recoveries of the 30 pesticides (organophosphorus, triazole, carbamate, nicotine, amide, and other different structures of pesticides) were in the range 71.0–110.8% (n = 5) (except those of prothioconazole and dinotefuran), with relative standard deviations lower than 13.5% in all the matrices under optimal conditions. The matrix effects were observed by comparing the slope of the matrix-matched standard calibration curve with that of the solvent. However, the matrix effects of the eight vegetables did not show evident regularities. For pepper, tomato, and shallot, a sizable number of pesticides (24, 21, and 21, respectively) showed suppressive matrix effects. On the other hand, for cucumber, Chinese flowering cabbage, and cabbage, a good number of pesticides (19, 18, and 15, respectively) showed negligible matrix effects. Furthermore, for carrot matrices, 21 pesticides showed a matrix enhancement effect. Excellent linearity was achieved at pesticide concentrations of 0.01–1.0 mg/L, and the limits of quantification (LOQ) for the developed method reached 0.01 mg/kg (except that for dinotefuran, which was 0.1 mg/kg), based on the spiked test. The developed method was successfully employed in the analysis of real samples in Nanning, China, and three pesticide residues (halosulfuron methyl, tebuconazole, and azoxystrobin) were commonly detected in vegetable samples. In the present study, a reliable method-validation performance and excellent cleanup effects were observed by using the modified MSPD method consisting of the FNPs in the cleanup step.

Preparation and properties of polyimide-based nanocomposites containing functionalized Fe3O4 nanoparticles

Polyimide (PI)/Fe3O4 nanocomposites were successfully prepared via the thermal curing of different amounts of Fe3O4 nanoparticles (2, 4, 6 and 8 wt%) functionalized by 3-aminopropyltriethoxy silane as a coupling agent, containing the poly(amic acid) derived from 5-diamino- N-(4-(4,5-diphenyl-1H-imidazol)phenyl)benzamide and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride. The effect of Fe3O4 nanoparticles on the structural, thermal and magnetic properties of nanocomposites was investigated. The Fourier transform infrared spectroscopy and scanning electron microscopy (SEM) results reveal that the surface of Fe3O4 nanoparticles is sufficiently compatible with PI through linkage of the coupling agent between Fe3O4 and the polymer. Also, the SEM image shows that Fe3O4 nanoparticles are dispersed uniformly in the polymer matrix, with a particle size of around 78 nm. The nanocomposites of 2 and 8 wt% exhibit the saturation magnetization values of 0.055 and 0.170 emu g− 1, respectively. The thermogravimetric analysis data show that the thermal stability of the nanocomposites is improved as compared to the pure PI.

A superparamagnetic Fe3O4-TiO2 composite coating on titanium by micro-arc oxidation for percutaneous implants.

A micro-magnetic field can affect the cell response and the subsequent tissue integration of implants. To improve the weak skin integration of percutaneous Ti implants, herein, superparamagnetic TiO2 coatings with Fe3O4 nanoparticles (NPs) were fabricated by micro-arc oxidization, and the magnetic field gradient induced by Fe3O4 was expected to enhance the fibroblast response in vitro and bio-sealing in vivo. Moreover, the surface properties of TiO2 coatings with Fe3O4 in different amounts were investigated, and the fibroblast and Staphylococcus aureus response in vitro as well as skin integration in vivo were evaluated. The obtained results showed that with an increase in the amount of Fe3O4 NPs in the electrolyte, more Fe3O4 were incorporated into the TiO2 coatings, and the Fe content could reach 4.41 wt%. The incorporation of Fe3O4 endowed TiO2 with superparamagnetism without changing its surface properties including the phase composition, Ca2+ release, roughness and hydrophilicity. The Fe3O4 NPs with the size of about 10 nm were mainly distributed in the near-surface region of TiO2. With an increase in the amount of Fe3O4 in TiO2, the magnetic property of TiO2 increased, and the fibroblast response, including proliferation, phenotype and extracellular collagen secretion, were improved. Compared to pure TiO2, TiO2 with 4.41 wt% Fe reduced bacterial reproduction to about 60% and efficiently prevented the recession and inflammatory reaction of soft tissue, showing good integration with skin tissues. Thus, herein, we provide a potential coating that can be applied on percutaneous Ti implants.

Synthesis and Characterization of Magnetically Modified Composites (TiNT/CNT/Fe3O4)

In this study, Titania nanotube (TiNT) had been modified by combining it with carbon nanotube (CNT) and magnetic material, Fe3O4, forming magnetically modified composite (TiNT/CNT/Fe3O4). Magnetic properties were added to the composite to overcome photocatalytic application problem for waste water treatment case, especially the catalyst recovery issue. Prior to the modifications, TiNT was synthesized from TiO2 P25 using hydrothermal process at 130 °C for 6 h. TiNT and CNT were then combined using hetero agglomeration process in acid condition to obtain TiNT/CNT composite. Various amount of Fe3O4 nanoparticles were then composed on the surface of TiNT/CNT using ultrasonic assisted in-situ process, producing TiNT/CNT/Fe3O4 magnetic composites. The samples were analyzed with various characterizations: zeta potential, FT-IR, FE-SEM/EDX, XRD, and VSM. Experimental results show that TiNT/CNT/Fe3O4 composite with good crystallinity and morphology had been successfully synthesized. The optimal amount of Fe3O4 in TiNT/CNT/Fe3O4 magnetic composite was 0.3 times the amount of TiNT to minimize the photodissolution effect, while the composite was still categorized as superparamagnetic materials (with the saturation magnetization value of 21.1 emu/g and coercivity of 84.4 oe). The magnetic separation test also confirmed that prepared magnetic composites could be effectively separated from the test solution.

Centrifugation free and air-assisted liquid-liquid microextraction based on deep eutectic solvent for determination of rare ginsenosides in Kang'ai injection

A simple, effective and convenient enrichment method coupled with high performance liquid chromatography (HPLC) was established for the analysis of rare ginsenosides in Kang'ai (KA) injection. Air assisted liquid-liquid microextraction was used in this work for the first time to determine the rare ginsenosides in KA injection. Deep eutectic solvent (DES) and tetrahydrofuran (THF) were specially selected as a novel green extraction solvent and an emulsified solvent, respectively. To remove the DES droplets, Fe3O4 nanoparticles were used. Therefore, centrifugation was free in this work, which can increase the efficiency of analysis procedure. Moreover, Fe3O4 nanoparticles were reusable. To achieve better extraction efficiency and enrichment factor, the experimental conditions have been optimized, including type and volume of DES and emulsified solvent, amount of Fe3O4 nanoparticles and inorganic salt, and pH value. Under the optimum extraction condition, the validation parameters show the limits of detection (LODs) are in the range from 10.2 ng/mL to 137.8 ng/mL and the limits of quantity (LOQs) are in the range from 55.5 ng/mL to 428.5 ng/mL. The recoveries of analytes range from 91.3% to 106.7% with the relative standard deviations (RSDs) ranging from 1.2% to 4.5%. The recommended approach was utilized to acquire the information of constituents in KA injection. Moreover, the results in this research could provide a study basis for further study of KA injection.

Synthesis, characterization and performance evaluation of Fe3O4/PES nano composite membranes for microbial fuel cell

In this study, nanocomposites based on polyethersulfone (PES) with different amounts of Fe3O4 nanoparticles have been synthesized, to be used as proton exchange membranes in a microbial fuel cell (MFC). Such new low-cost separators were fabricated by melt blending and tested in an MFC system.The membranes have been characterized in terms of their mechanical and thermal properties and the results compared to those of commercially available ones (Nafion 117 and CMI 7000). The efficiency of the newly synthesized membranes was assessed in H-type MFC system. Synthetic wastewater using sodium acetate as carbon source was prepared. Total Organic Carbon (TOC) reduction, pH and Open Circuit Voltage (OCV) were daily monitored. Linear Sweep Voltammetry (LSV) was used to optimize the amount of nanoparticles in terms of maximum current and power.The maximum power (9.59 ± 1.18 mW m−2) and current density (38.38 ± 4.73 mA m−2) generation were obtained by using a composite with 20 wt% of nanoparticles. Results of mechanical characterization pointed out that increasing nanoparticles content can compromise the mechanical properties of membranes leading to a significant brittle behavior, while the tensile strength was found to be suitable for durable MFC operations.

Enhancing purification efficiency of affinity functionalized composite agarose micro beads using Fe3O4 nanoparticles.

In this work, a series of magnetic and nonmagnetic agarose matrices were fabricated for protein purification. Certain amounts of Fe3O4 nanoparticles were encapsulated in agarose beads to form composite magnetic matrices with enhanced purification efficiency. Structure and morphology of prepared matrices were studied by optical and scanning electron microscopes, FT-IR, and BET-BJH analysis. The prepared matrices had regular spherical shape, followed by a uniform size distribution. By nanoparticles addition, the number of mesopores decreased while population of pores with radius ≤10nm increased; thus, higher specific area achieved. According to VSM results, magnetization degree was one of the characteristics affected by agarose content of the beads. A dye ligand, Cibacron Blue F3GA (CB), was covalently bound to beads to adsorb Bovine serum albumin. CB concentration was determined by elemental analysis. It was shown that magnetic beads hold higher CB concentrations than nonmagnetic ones due to higher specific area. As a result, magnetic 8%-agarose beads had the highest affinity adsorption capacity in static experiments. Moreover, breakthrough curves were monitored to calculate dynamic binding capacity. And, it was shown that magnetic 4%-agarose had the highest adsorbing amount (6.00mg/mL). It was implied that pore diffusion in magnetic 4%-agarose may be the reason for higher dynamic capacity. Plus, column efficiency was evaluated. It was revealed that all magnetic beads had lower HETP (0.11, 0.12 and 0.11cm for magnetic 4, 6, and 8%-agarose beads) than nonmagnetic ones (P-value<0.05).

Chemical modification of magnetite nanoparticles and preparation of acrylic-base magnetic nanocomposite particles via miniemulsion polymerization

Nowadays, magnetic nanocomposite particles have attracted many interests because of their versatile applications. A new method for chemical modification of Fe3O4 nanoparticles with polymerizable groups is presented here. After synthesis of Fe3O4 nanoparticles by co-precipitation method, they were modified sequentially with 3-aminopropyl triethoxysilane (APTES), acryloyl chloride (AC) and benzoyl chloride (BC) and all were characterized by FTIR, XRD, SEM and TGA analyses. Then the modified magnetite nanoparticles with unsaturated acrylic groups were copolymerized with methyl methacrylate (MMA), butyl acrylate (BA) and acrylic acid (AA) through miniemulsion polymerization. Although several reports exist on preparation of magnetite-base polymer particles, but the efficiency of magnetite encapsulationwith reasonable content and obtaining final stable latexes with limited aggregation ofFe3O4 are still important issues. These were considered here by controlling reaction parameters. Hence, a seriesofmagneticnanocomposites latex particlescontaining different amounts of Fe3O4 nanoparticles (0–10wt%) were prepared with core-shell morphology and diameter below 200nm and were characterized by FT-IR, DSC and TGA analyses. Their morphology and size distribution were studied by SEM, TEM and DLS analyses too. Magnetic properties of all products were also measuredby VSM analysis and the results revealed almost superparamagnetic properties for the obtained nanocomposite particles.

Surface modification of sulfonated polyvinylchloride cation-exchange membranes by using chitosan polymer containing Fe3O4 nanoparticles

Sulfonated polyvinylchloride (SPVC) cation-exchange membranes were coated using chitosan solutions comprising different amounts of Fe3O4 nanoparticles. Influence of chitosan immobilization as well as nanofiller concentration on the electrochemical performance of the membranes was investigated. Electrochemical properties of the membranes including permselectivity, ionic permeability, and areal resistance were studied using an equipped electrodialysis setup and NaCl solution as model electrolyte. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were employed for membrane characterization. Electrochemical performance of the SPVC membranes was improved by coating chitosan polymer. In addition, ionic permeability and permselectivity of the membranes were initially raised by increasing nanoparticles concentration from nil to 2 wt% and then decreased by further insertion of the nanofiller. The areal resistance of the plain SPVC membrane was decreased from 9.4 to 2.9 (ohm) by coating of chitosan solution including optimum value of nano-Fe3O4 due to electrical potential field enhancement across the membrane.

Fabrication of mesoporous graphene electrodes with enhanced capacitive deionization

Mesoporous graphene electrodes are facilely fabricated via a simple thermal treatment of graphene oxide as well as site-localized etching of Fe3O4 nanoparticles (E-Gr-Fe3O4). Influences of FeCl2 precursor on the amount of Fe3O4 nanoparticles and textural properties of E-Gr-Fe3O4 are investigated. The obtained graphene framework exhibits a porous structure with a specific surface area of 362m2/g and excellent specific capacity of 128 F/g, which is twice higher than that of pristine reduced graphene oxide electrodes (RGO, 66F/g). With the enhanced electrochemical capacity, low inner resistance and good stability, the as-prepared mesoporous E-Gr-Fe3O4 electrode exhibits a high electrosorptive capacity of 10.3mg/g when the initial NaCl conductivity is 300μs/cm, which is much higher than that of RGO (6mg/g). The results demonstrate that E-Gr-Fe3O4 is quite a promising candidate as high performance electrodes for capacitive deionization.

Magnetic mixed hemimicelles solid‐phase extraction coupled with high‐performance liquid chromatography for the extraction and rapid determination of six fluoroquinolones in environmental water samples

In this study, a mixed hemimicelle solid-phase extraction method based on Fe3 O4 nanoparticles coated with sodium dodecyl sulfate was applied for the preconcentration and fast isolation of six fluoroquinolones in environmental water samples before high-performance liquid chromatography determination. The main factors affecting the extraction efficiency of the analytes, such as amount of surfactant, amount of Fe3 O4 nanoparticles, extraction time, sample volume, sample pH, ionic strength, and desorption conditions, were investigated and optimized. The method has detection limits from 0.05 to 0.1 ng/mL and good linearity (r ≥ 09948) in the range 0.1-200 ng/mL depending on the fluoroquinolone. The enrichment factor is ∼200. The recoveries (at spiked levels of 1, 5, and 50 ng/mL) are in the range of 79-120%.

Surfactant coated magnetic nanoparticle‐based solid‐phase extraction coupled with spectrophotometric detection for determination of ultra‐trace amounts of indomethacin in biological fluids

A novel mixed hemimicelle-based solid-phase extraction method using cetyltrimethylammonium bromide (CTAB) adsorbed onto the surface of magnetic Fe3O4 nanoparticles was developed for extraction/preconcentration of ultra-trace amounts of indomethacin from biological fluids. Magnetic nanoparticles were synthesised via a simple chemical co-precipitation method and characterised by a transmission electron microscope, an X-ray diffractometer and Fourier transform infrared techniques. The method utilises the unique properties of Fe3O4 nanoparticles including high surface area and superparamagnetism causing rapid separation (<20 min) and low adsorbent usage (only 50 mg). A comprehensive study on the parameters affecting the adsorption efficiency such as the amount of CTAB, pH of the solution, desorption conditions, amount of Fe3O4 nanoparticles, extraction and preconcentration time, sample volume and ionic strength are presented. Under optimum conditions, the method's linearity was over a range of 25–450 ng ml−1.‏ The limit of detection of 8.6 ng ml−1, an enrichment factor of 99 and the relative standard deviation (%RSD) of 1.9% (for a concentration of 50 ng ml−1) were obtained. The method was successfully applied to determine indomethacin in human plasma and urine samples. Good recoveries (89–102%) with low %RSD, (1.7–2.7%) were achieved.