Ultrasound-assisted Magnetic Solid Phase Extraction Research Articles

Magnetic chitosan-zeolite composite as an adsorbent in ultrasound-assisted magnetic solid phase extraction of tetracyclines in water samples

An ultrasound-assisted magnetic solid-phase extraction method was developed to pre-concentrate tetracyclines (TCs) in wastewater and river water. The magnetic chitosan-zeolite composite was used as an adsorbent. The morphological and structural properties of the adsorbent were characterised by various analytical techniques. The factors affecting the ultrasound-assisted magnetic solid-phase extraction method were optimised using a central composite design. A high performance liquid chromatography equipped with a photodiode array detector was used to quantify TCs in wastewater and river water samples. Under optimised parameters, the developed analytical approach gave acceptable linearity (LOQ-400 µg L−1) with correlation coefficients exceeding 0.993, while the detection and quantitation limits ranged from 0.05–0.67 and 0.14–2.03 µg L−1, respectively. Attained recoveries were 90–101%, with intraday and interday precision expressed as the relative standard deviation (%RSD) below 5%. Even though the target analytes (tetracycline, oxytetracycline and oxytetracycline) were not detected in environmental samples, the synthesised adsorbent was suitable for the isolation of TCs in a complex matrix resulting in an accurate, precise, rapid and sensitive analytical method.

Magnetic Porous Polymer with −OH Groups as Sorbent for Excellent Extraction and Removal of Personal Care Products from Water

Further improvement on the adsorption performance of microporous organic polymers (MOPs) by delicate design remains a challenge. Herein, a magnetic hydroxyl-functioned microporous organic polymer (Fe3O4/Hy-MOP) was prepared and characterized by a series of techniques, including transmission electron microscopy, vibration sample magnetometry, Fourier transform infrared spectrometry, thermal gravimetric analysis, and zeta potential analysis. As an adsorbent for ultrasound-assisted magnetic solid phase extraction of three personal care products (PCPs, triclosan, triclocarban, and 2-hydroxy-4-methoxybenzophenone), the obtained Fe3O4/Hy-MOP exhibited excellent performance in extracting three PCPs (89–95%) from water samples owing to its hydrophilicity, inherent microporous structure, and easy magnetic separation. Moreover, probing of adsorption behavior by triclosan upon Fe3O4/Hy-MOP surfaces demonstrated that the adsorption process followed the models of Freundlich isotherm, together with pseudo-second-order kinetics. The extraction and adsorption mechanism involved polar force, π–π interaction, and hydrophobic interaction between Fe3O4/Hy-MOP and PCPs. Particularly, the stability and magnetism of Fe3O4/Hy-MOP confer excellent cycling performance, allowing for five recycling iterations without a significant decrease in performance. Such results indicated that magnetic adsorbent Fe3O4/Hy-MOP has potential for application in the extraction and removal of PCPs from actual water samples.

Integrated ultrasound-assisted magnetic solid-phase extraction for efficient determination and pre-concentration of polycyclic aromatic hydrocarbons from high-consumption soft drinks and non-alcoholic beers in Iran.

In the present research, an ultrasound-assisted magnetic solid-phase extraction coupled with a gas chromatography-mass spectrometry hybrid system was developed for the extraction/determination of trace amounts of polycyclic aromatic hydrocarbons in high-consumption soft drinks and non-alcoholic beers in Iran using magnetite graphene oxide adsorbent. The magnetite graphene oxide was characterized by scanning electron microscope, transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and vibrating-sample magnetometer techniques. The highest extraction recovery (73.05%-95.56%) and enrichment factor (90.65-106.38) were obtained at adsorbent mass: 10mg, adsorption time: 30min, salt addition: sodium chloride 10% w/v, desorption time: 20min, eluent type: hexane: acetone (1:1, v/v), and desorption solvent volumes: 200 μl. Under optimum conditions, the linearity range for polycyclic aromatic hydrocarbons determination was 0.2-200ng/mlwith a coefficient of determination>0.993, the limit of detection=0.09-0.21ng/ml, the limit of quantitation=0.3-0.7ng/ml, and relative standard deviation<8.1%, respectively. Relative recoveries in spiked real samples ranged from 94.67 to 109.45% with a standard deviation<6.05%. The proposed method is effective, sensitive, and reusable and it is promising for the analysis of polycyclic aromatic hydrocarbons residues in environmental samples.

Magnetic Ion Imprinted Polymers (MIIPs) for Selective Extraction and Preconcentration of Sb(III) from Environmental Matrices.

Antimony(III) is a rare element whose chemical and toxicological properties bear a resemblance to those of arsenic. As a result, the presence of Sb(III) in water might have adverse effects on human health and aquatic life. However, Sb(III) exists at very ultra-trace levels which may be difficult for direct quantification. Therefore, there is a need to develop efficient and reliable selective extraction and preconcentration of Sb(III) in water systems. Herein, a selective extraction and preconcentration of trace Sb(III) from environmental samples was achieved using ultrasound assisted magnetic solid-phase extraction (UA-MSPE) based on magnetic Sb(III) ion imprinted polymer-Fe3O4@SiO2@CNFs nanocomposite as an adsorbent. The amount of antimony in samples was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The UA-MSPE conditions were investigated using fractional factorial design and response surface methodology based on central composite design. The Sb(III)-IIP sorbent displayed excellent selectivity towards Sb(III) as compared to NIIP adsorbent. Under optimised conditions, the enrichment factor, limit of detection (LOD) and limit of quantification (LOQ) of UA-MSPE/ICP-OES for Sb(III) were 71.3, 0.13 µg L−1 and 0.44 µg L−1, respectively. The intra-day and inter-day precision expressed as relative standard deviations (%RSDs, n = 10 and n = 5) were 2.4 and 4.7, respectively. The proposed analytical method was applied in the determination of trace Sb(III) in environmental samples. Furthermore, the accuracy of the method was evaluated using spiked recovery experiments and the percentage recoveries ranged from 95–98.3%.

Ultrasound-assisted magnetic solid-phase extraction of polycyclic aromatic hydrocarbons and nitrated polycyclic aromatic hydrocarbons from water samples with a magnetic polyaniline modified graphene oxide nanocomposite

A novel magnetic graphene oxide nanocomposite modified with polyaniline (Fe3O4@GO-PANI) was synthesized and applied for the magnetic solid-phase extraction of polycyclic aromatic hydrocarbons (PAHs) (i.e. fluorene, phenanthrene and pyrene) and nitrated polycyclic aromatic hydrocarbons (N-PAHs) (i.e. 2-nitrofluorene, 9-nitroanthracene, 1-nitropyrene and 3-nitrofluoranthene) prior to their determination by gas chromatography-mass spectrometry. The prepared nanomaterial was characterized by scanning electron microscopy, X-ray diffraction, and Fourier transform-infrared spectroscopy. The main experimental parameters affecting the extraction and desorption steps of the MSPE procedure were investigated and optimized. Under optimum conditions, coefficients of determination (r2) ranged between 0.9970 and 0.9995, limits of detection (LODs, S/N = 3) ranged between 0.04–0.05 ng mL−1 for PAHs and 0.01–0.11 ng mL−1 for N-PAHs, while the relative standard deviation for intra-day and inter-day repeatability were lower than 10.0% for PAHs and N-PAHs. The method was successfully applied to the analysis of tap, mineral and river water samples. Relative recoveries in spiked water samples ranged between from 91.6 to 114% and from 92.3 to 110% for PAHs and N-PAHs, respectively. The proposed method is simple, rapid, sensitive and the Fe3O4@GO-PANI sorbent can be reused for at least 15 times without significant decrease in extraction recovery.

The extraction of four endocrine disrupters using hollow N-doped mesoporous carbon spheres with encapsulated magnetite (Fe3O4) nanoparticles coupled to HPLC-DAD determination

Magnetite/hollow core–shell N-doped mesoporous carbon sphere (Fe3O4/N-HCSCs) composites were prepared as a sorbent for ultrasound-assisted magnetic solid-phase extraction of four endocrine disrupter compounds (EDCs) from water samples prior to the EDCs determination by high-performance liquid chromatography with a diode array detector (HPLC-DAD) (analytical wavelength, 260 nm). The Fe3O4/N-HCSCs, which contained N-HCSCs with encapsulated magnetite nanoparticles, were also characterized. The extraction and elution conditions were optimized by a one-factor-at-a-time approach using prepared Fe3O4/N-HCSCs for the selected the EDCs (triclosan, triclocarban, bisphenol A, and tetrabromobisphenol A bis(allyl)ether). Under the optimum extraction/elution conditions, the previously mentioned procedure achieved low detection limits (0.05–0.1 μg·L−1), high recovery values (88.0%–97.0%), satisfactory preconcentration factors (115–136), and good reproducibility (relative standard deviations of less than 5.8%, n = 4). Kinetic and isotherm studies showed that the adsorption process followed pseudo-second-order kinetic and Freundlich equilibrium models. The Fe3O4/N-HCSCs had a good selectivity for the selected EDCs, mainly due to the large specific surface area of the sorbent, the presence of nitrogen species on the sorbent, and the hydrophobic interaction between the EDCs and sorbent. This work revealed the potential value of the method for rapidly screening EDCs in environmental water samples.

Magnetic metal organic framework for pre-concentration of ampicillin from cow milk samples

The aim of this study is a present of a simple solvothermal synthesis approach to preparation of Cu-based magnetic metal organic framework (MMOF) and subsequently its application as sorbent for ultrasound assisted magnetic solid phase extraction (UAMSPE) of ampicillin (AMP) from cow milk samples prior to high performance liquid chromatography-Ultraviolet (HPLC-UV) determination. Characteristics of prepared MMOF were fully investigated by different techniques which showed the exclusive properties of proposed sorbent in terms of proper functionality, desirable magnetic property and also high specific surface area. Different influential factors on extraction recovery including sorbent dosage, ultrasonic time, washing solvent volume and eluent solvent volume were assessed using central composite design (CCD) based response surface methodology (RSM) as an operative and powerful optimization tool. This is the first report for determination of AMP using MMOF. The proposed method addressed some drawbacks of other methods and sorbents for determination of AMP. The presented method decreases the extraction time (4 min) and also enhances adsorption capacity (250 mg/g). Moreover, the magnetic property of presented sorbent (15 emu/g) accelerates the extraction process which does not need filtration, centrifuge and precipitation procedures. Under the optimized conditions, the proposed method is applicable for linear range of 1.0–5000.0 μg/L with detection limit of 0.29 μg/L, satisfactory recoveries (≥95.0%) and acceptable repeatability (RSD less than 4.0%). The present study indicates highly promising perspectives of MMOF for highly effective analysis of AMP in complicated matrices.

Covalently bonded dithiocarbamate-terminated hyperbranched polyamidoamine polymer on magnetic graphene oxide nanosheets as an efficient sorbent for preconcentration and separation of trace levels of some heavy metal ions in food samples

Graphene oxide nanosheets were modified with magnetite nanoparticles, and a dithiocarbamate-terminated hyper branched polyamidoamine dendrimer was then covalently attached to their surface. The resulting material is shown to be an efficient sorbent for preconcentration of the Pb(II), Cd(II), Ni(II), Cu(II) and Cr(III) via ultrasound-assisted magnetic solid phase extraction. The sorbent was characterized by transmission electron microscopy, field emission scanning electron microscopy, FT-IR, X-ray diffraction and vibrating sample magnetometry. The effects of pH value, sorbent dosage, eluent volume, and sonication time were optimized by central composite design. The metals were quantified by flame atomic absorption spectroscopy (FAAS). Under optimized conditions, the method has a linear response in 3.5–150, 0.9–15, 3–100, 1.8–50 and 2.6–75 µg L−1 concentration range for Pb(II), Cd(II), Ni(II), Cu(II) and Cr(III), respectively. The detection limits are as low as 1.0, 0.27, 0.9, 0.54 and 0.8 µg L−1 for Pb(II), Cd(II), Ni(II), Cu(II) and Cr(III), respectively.

Ultrasound-assisted magnetic solid phase extraction of lead and thallium in complex environmental samples using magnetic multi-walled carbon nanotubes/zeolite nanocomposite

Magnetic multi-walled carbon nanotubes@zeolite (MWCNT-Fe3O4@Zeo) nanocomposite was facilely synthesized using a one-pot solvothermal method. The MWCNT-Fe3O4@Zeo was characterized by VSM, BET, XRD, TEM and SEM/EDS. The Zeolite-coated multi-walled carbon nanotubes–magnetite was used as an adsorbent in ultrasonic-assisted magnetic solid phase extraction (UA-MSPE) for preconcentration of trace Pb and Tl. The analytes were detected and quantified using inductively coupled plasma optical emission spectrometry (ICP-OES). The optimization of experimental parameters affecting the preconcentration method was achieved using a multivariate approach. Under optimal experimental conditions, the linearity ranged from 0.1 to 500 μg L−1 for lead and 0.1–600 μg L−1 for thallium. Preconcentration factors, limits of detection and quantification for Pb and Tl ranged from 90 to 100, 0.28–0.23 μg L−1, 0.93–0.77 μg L−1. The intraday precisions (repeatability, n = 20) expressed as the relative standard deviation, were found to be 1.6% and 1.4% for Pb and Tl, respectively. In addition, the interday precisions (reproducibility, n = 5) were 2.6% and 3.1% for Pb and Tl, respectively. The accuracy of the method was investigated using standard reference material as well as spiked recovery test and satisfactory recoveries (97–99.3%) were obtained. The maximum adsorption capacities were 37.8 mg g−1 and 44.5 mg g−1, for Pb and Tl, respectively. The developed UA-MSPE/ICP-OES method was effectively applied for simultaneous preconcentration and determination of Pb and Tl in environmental samples.

Determination of Pyrethroids in Paris polyphylla Sample by High-Performance Liquid Chromatography Using Ultrasound-Assisted Magnetic Solid-Phase Extraction

A novel ultrasound-assisted magnetic solid-phase extraction (UA-MSPE) was developed for the separation/preconcentration of trace amounts of pyrethroids (fenpropathrin, fenvalerate, deltamethrin, and bifenthrin) in Paris polyphylla sample using carbon nanotubes based on Fe3O4 magnetic nanoparticles (Fe3O4@CNT MNPs), and high-performance liquid chromatography-UV is described. High recoveries of pyrethroids were obtained at a low MNPs concentration because sonication enhances the contact chances between magnetic nanoparticles and extractable analytes and promotes the extractability of the MSPE process. After the extraction, the adsorbent can be conveniently separated from the sample solution by an external magnet, and the adsorbed analytes were eluted from magnetic Fe3O4@CNT. The main factors influencing the extraction efficiency including the amount of the MNPs, the extraction time, the pH of sample solution, the sonicating time, and the desorption conditions were studied and optimized. Under the optimized experimental conditions, a good linearity was observed in the range of 1-100.0 ng mL−1 for all the analytes, with the correlation coefficients (r) ranging from 0.9962 to 0.9991. The limits of detection of the four pyrethroids are 0.53, 0.26, 0.47, and 0.67 ng mL−1, respectively. The recoveries of the method were in the range between 85.5% and 93.2%. This method is much faster and more effective than traditional SPE methods, and it is promising for the analysis of pyrethroids residues.

Magnetic hybrid support for ultrasound-assisted magnetic solid-phase extraction of polycyclic aromatic hydrocarbons from produced water

This work describes the synthesis of two hybrid organic-inorganic supports with magnetic properties, using water with a high content of natural organic matter (NOM) as solvent and to compose the organic phase. The materials were used in the ultrasound-assisted magnetic solid-phase extraction (UAMSPE) and magnetic dispersive solid-phase extraction (MdSPE) of five polycyclic aromatic hydrocarbons (PAHs) from produced water (PW). The best extraction conditions were achieved using UAMSPE with 20.0 mg of the adsorbent, total extraction time of 5 min, and 10 mL of ethyl acetate as extractant. The linear range, limit of detection (LOD), limit of quantification (LOQ), correlation coefficient (r), and relative standard deviation (RSD) could reach 0.500–100 μg L−1, 0.010–0.020 μg L−1 (based on S/N = 3), 0.03–0,060 (based on S/N = 3), 0.9943, and 6.7% (50 μg L−1) respectively. Upon optimization, the analysis of two PW samples from different wells found PAHs concentrations in the ranges 0.6–1.7 μg L−1 (sample APP1) and 0.5–1.6 μg L−1 (sample APP2). The method was successfully applied to the determination of PAHs in produced water.

Ultrasound-assisted dispersive magnetic solid phase extraction based on metal–organic framework/1-(2-pyridylazo)-2-naphthol modified magnetite nanoparticle composites for speciation analysis of inorganic tin

A novel magnetic metal–organic framework (MMOF) consisting of MIL-101(Cr) and 1-(2-pyridylazo)-2-naphthol-modified magnetite nanoparticles was synthesized and utilized for the ultrasound-assisted magnetic solid phase extraction and speciation analysis of Sn(ii) and Sn(iv) at trace amounts.

Selective determination of caffeine in foods with 3D-graphene based ultrasound-assisted magnetic solid phase extraction

An efficient method was applied for extraction of caffeine in food samples. Three-dimensional graphene-Fe3O4 (3D-G-Fe3O4) nanoparticles was successfully synthesized and used as adsorbent in magnetic solid phase extraction (MSPE) step. The properties of synthesized adsorbent were characterized by fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), vibrating sample magnetometer (VSM), X-ray diffraction (XRD), Raman spectroscopy, Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) methods. The influence of main parameters of extraction procedure such as ultrasound parameter, amount of nanoparticles, pH, salt concentration and desorption condition were investigated and optimized. Under the optimized experimental conditions, the figure of merit results showed excellent linear dynamic range (LDR) of 0.5–500 µg mL−1, with determination coefficient (R2) higher than 0.996 and limit of detection (LOD) of 0.1 µg mL−1. Intra- and inter-day relative standard deviations (RSDs) were less than 5.9 and 7.1%, respectively. The method was successfully applied for determination of caffeine in different food samples.

Preparation of magnetic Fe3O4 nanocomposites modified with MnO2, Al2O3, Au and their application for preconcentration of arsenic in river water samples

In this study, the nanometer-sized ferrous-ferric oxide magnetic nanocomposite (Fe3O4@MnO2@Al2O3@Au) was successfully synthesized using co-precipitation and sol gel methods The structural, morphological and magnetic properties of the nanocomposite material were characterized by FTIR, BET, XRD, SEM/EDS, Zeta-potential measurements, TEM and VSM. The nanocomposite was applied as a sorbent for preconcentration of As via ultrasound assisted magnetic solid phase extraction (UA-MSPE). The preconcentrated arsenic was quantified using ICP-MS. A 25−1 fractional factorial design was used as a tool for optimizing the developed analytical methodologies. Under optimized conditions, the limit of detection and quantification were 8.6 and 28.5 ng L−1 respectively. The intraday (n = 15) and interday (n = 5) precisions of the developed UA-MSPE method expressed in terms of relative standard deviation (%RSD) were 4.1 and 6.2% and the enrichment factor was found to be 95. The extraction efficiency of the current method was greater than 95%. The developed UA-MSPE method was successfully applied in the preconcentration of arsenic in environmental water samples and nanocomposites modified with MnO2, Al2O3, Au and their application for preconcentration of arsenic in river water sample and the concentration ranged from 0.13–0.18 μg L−1. The Fe3O4@MnO2@Al2O3@Au nanoadsorbent combined the advantages of magnetic separability and high affinity toward arsenic adsorption.

Super paramagnetic core–shells anchored onto silica grafted with C8/NH2 nano-particles for ultrasound-assisted magnetic solid phase extraction of imipramine and desipramine from plasma

In current work the Fe3O4 magnetic nano-particles anchored to core–shells of SiO2 which grafted by C8/NH2 dual mixed groups, have been synthesized. The magnetic nano-particles were characterized by scanning electron microscopy, X-ray diffraction spectroscopy, and zeta-potential reader. The resulted nano-particles have spherical structure with diameters in the range of 105 to 110 nm. A magnetic solid phase extraction method was developed for extraction of imipramine and desipramine from human plasma samples under ultrasonic conditions by using of prepared NPs as sorbent. The MNPs were dispersion in plasma under sonicated conditions, accumulated by an external magnetic field and washed with Briton-Robinson buffer-acetonitrile solution (0.05 mol l−1, pH = 5, 10%V/V). The drugs were removed by methanol and quantified by gas chromatography. The calibration curves (correlation coefficient > 0.99) for IMP and DES were linear in the concentration range of 0.005 to 5 and 0.01 to 4 μg ml−1, respectively. The LOD, LOQ, intra and inter-day precision values were measured too. The proposed Fe3O4/SiO2/C8/NH2 MNPs could be applied for 3.0 times.

A hyperbranched polyamidoamine dendrimer grafted onto magnetized graphene oxide as a sorbent for the extraction of synthetic dyes from foodstuff

Graphene oxide nanosheets were modified with magnetite nanoparticles, and a hyperbranched polyamidoamine dendrimer was then covalently attached to their surface. The resulting material is shown to be an efficient sorbent for preconcentration of the synthetic dyes tartrazine, quinoline yellow, sunset yellow and carmoisine via ultrasound-assisted magnetic solid phase extraction. The electrostatic interaction and hydrogen bonding were considered to be the main mechanism for the dyes adsorption. The sorbent was characterized by transmission electron microscopy, field emission scanning electron microscopy, FT-IR, X-ray diffraction and vibrating sample magnetometry. The effects of pH value, sorbent dosage, eluent volume, and sonication time were optimized by central composite design and desirability function. The dyes were quantified by HPLC with detection at 450 nm. Under optimized conditions, the method has a linear response in the 2–3000, 5–2000, 1–5000 and 2–2500 ng.mL−1 concentration range for tartrazine, quinoline yellow, sunset yellow and carmoisine, respectively. The limits of detection are as low as 0.6, 1.5, 0.3 and 0.6 for tartrazine, quinoline yellow, sunset yellow and carmoisine, respectively.

Magnetic carbon nanotubes modified with 1,4-diazabicyclo[2.2.2] octane are a viable sorbent for extraction of selective serotonin reuptake inhibitors

Carbon nanotubes were modified with magnetite nanoparticles, and 1,4-diazabicyclo[2.2.2]octane (DABCO) was then covalently attached to their surface. The resulting material is shown to be a viable sorbent for the preconcentration of the selective serotonin reuptake inhibitors citalopram, sertraline, fluvoxamine and fluoxetine via ultrasound-assisted magnetic solid phase extraction. The effects of pH value, sorbent dosage, eluent volume and salt concentration were optimized by central composite design and desirability function. The drugs were quantified by HPLC with UV detection. Detection limits are as low as 0.2, 0.25, 0.3, and 0.5 ng mL−1 for citalopram, sertraline, fluvoxamine and fluoxetine, respectively. The intra-day precisions (RSDs) are 91%. The sorbent can be reused 12 times without a noticeable decrease in extraction efficiency.

Preconcentration and speciation of chromium species using ICP-OES after ultrasound-assisted magnetic solid phase extraction with an amino-modified magnetic nanocomposite prepared from Fe3O4, MnO2 and Al2O3

The article describes a method for preconcentration and speciation of Cr(III) and Cr(VI) in river waters. It is based on ultrasound-assisted magnetic solid phase extraction employing a nanocomposite prepared from magnetite nanoparticles, manganese oxide and alumina oxide, and then functionalized with [3-(2-aminoethylamino)propyl] trimethoxysilane (AAPTMS). By taking advantage of the oxidative properties of MnO2, the Fe3O4@MnO2,Al2O3 nanocomposite was used for the preconcentration of total chromium. The AAPTMS-modified nanocomposite, in turn, is selective for Cr(VI). The concentration of Cr(III) can be calculated as the difference between total chromium and Cr(VI). The preconcentrated chromium species were quantified using ICP-OES. The method was optimized using response surface methodology. Under optimal conditions, the limit of detection and quantification are 20 and 50 pg ⋅ mL−1, respectively. The intraday and interday precisions of the method, expressed in terms of relative standard deviation, are 2.6 and 4.9%, respectively. In addition, the effects of potentially interfering ions were examined. The method was successfully applied to the speciation of chromium in spiked river water and a certified reference material.

Fe3O4/hydroxyapatite/graphene quantum dots as a novel nano-sorbent for preconcentration of copper residue in Thai food ingredients: Optimization of ultrasound-assisted magnetic solid phase extraction

Fe3O4/hydroxyapatite/graphene quantum dots (Fe3O4/HAP/GQDs) nanocomposite was synthesized and used as a novel magnetic adsorbent. This nanocomposite was characterized using scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and magnetization property. The Fe3O4/HAP/GQDs was applied to pre-concentrate copper residues in Thai food ingredients (so-called “Tom Yum Kung”) prior to determination by inductively coupled plasma-atomic emission spectrometry. Based on ultrasound-assisted extraction optimization, various parameters affecting the magnetic solid-phase extraction, such as solution pH, amount of magnetic nanoparticles, adsorption and desorption time, and type of elution solvent and its concentration were evaluated. Under optimal conditions, the linear range was 0.05–1500ngmL−1 (R2>0.999), limit of detection was 0.58ngmL−1, and limit of quantification was 1.94ngmL−1. The precision, expressed as the relative standard deviation of the calibration curve slope (n=5), for intra-day and inter-day analyses was 0.87% and 4.47%, respectively. The recovery study of Cu for real samples was ranged between 83.5% and 104.8%. This approach gave the enrichment factor of 39.2, which guarantees trace analysis of Cu residues. Therefore, Fe3O4/HAP/GQDs can be a potential and suitable candidate for the pre-concentration and separation of Cu from food samples. It can easily be reused after treatment with deionized water.

Ultrasound-assisted mixed hemimicelle magnetic solid phase extraction followed by high performance liquid chromatography for the quantification of atorvastatin in biological and aquatic samples

A method based on ultrasound-assisted magnetic solid phase extraction and HPLC-UV-Vis was developed for the isolation and preconcentration of atorvastatin using sodium dodecyl sulfate coated Fe3O4 magnetic nanoparticles.