Magnetic Solid-phase Microextraction Research Articles

Development of Magnetic Solid Phase Micro-Extraction (MSPE) Method for the Extraction and Preconcentration of the Selected β-Blockers in the Environmental Wastewaters

AbstractEmerging organic pollutants s have always been the greatest environmental concern due to their ubiquity and distinguished adverse effects. These are mostly water-bone pollutants flagged as endocrine disruptors and can greatly inconvenience the ecosystem. Among others, β-blockers have also been detected in the environment at various concentrations that threaten the well-being of humans and animals. In this work, NH2-MIL-101(Cr) doped magnetic nanoparticles nanocomposite was successfully synthesised and characterised using analytical techniques such as X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller (BET) and transmission electron microscopy (TEM). The Fe3O4@NH2-MIL-101(Cr) was then used as an adsorbent to extract the selected β-blockers in the environmental wastewater. The selected β-blockers were quantified using a high-performance liquid chromatography-diode array detector (HPLC-DAD). Parameters affecting the extraction were screened and optimised using fractional factorial design (FFD) and central composite design (CCD), respectively. Under optimum conditions, the LODs were 0.057 and 0.065 µg L− 1, and LOQs were 0.19 and 0.22 µg L− 1 for acebutolol (ACE) and metoprolol (MET), respectively. The calibration curve exhibited the linearity range of 0.2–1200 µg L− 1 with correlation coefficients of 0.9987 and 0.9968 for ACE and MET, respectively. Repeatability studies demonstrated the %RSD of 0.63 and 0.74% for MET and ACE. At the same time, reproducibility studies displayed the %RSD of 1.057 and 1.178% for MET and ACE, respectively. Spike recovery experiments were carried out to assess the performance of MSPE in real samples, and over 88% of both analytes were recovered. This indicated that the MSPE method could enrich various organic pollutants from different environmental matrices.

High-efficient separation of deoxyribonucleic acid from pathogenic bacteria by hedgehog-inspired magnetic nanoparticles microextraction

Efficient separation of deoxyribonucleic acid (DNA) through magnetic nanoparticles (MN) is a widely used biotechnology. Hedgehog-inspired MNs (HMN) possess a high-surface-area due to the distinct burr-like structure of hedgehog, but there is no report about the usage of HMN for DNA extraction. Herein, to improve the selection of MN and illustrate the performance of HMN for DNA separation, HMN and silica-coated Fe3O4 nanoparticles (Fe3O4@SiO2) were fabricated and compared for the high-efficient separation of pathogenic bacteria of DNA. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) are typical Gram-negative and Gram-positive bacteria and are selected as model pathogenic bacteria. To enhance the extraction efficiency of two kinds of MNs, various parameters, including pretreatment, lysis, binding and elution conditions, have been optimized in detail. In most separation experiments, the DNA yield of HMN was higher than that of Fe3O4@SiO2. Therefore, a HMN-based magnetic solid-phase microextraction (MSPE) and quantitative real-time PCR (qPCR) were integrated and used to detect pathogenic bacteria in real samples. Interestingly, the HMN-based MSPE combined qPCR strategy exhibited high sensitivity with a limit of detection of 2.0 × 101 CFU mL−1 for E. coli and 4.0 × 101 CFU mL−1 for S. aureus in orange juice, and 2.8 × 102 CFU mL−1 for E. coli and 1.1 × 102 CFU mL−1 for S. aureus in milk, respectively. The performance of the proposed strategy was significantly better than that of commercial kit. This work could prove that the novel HMN could be applicable for the efficient separation of DNA from complex biological samples.

β-ketoenamine covalent organic frameworks based magnetic solid-phase microextraction for rapid determination of 12 organophosphate esters in surface water

In this work, Fe3O4/Tp-BHBD β-ketoenamine covalent organic framework (COF) was rapidly prepared. Then, it was used as magnetic solid phase microextraction (MSPE) adsorbents for the adsorption and determination of organophosphate ester (OPE) residues in surface water coupling with liquid chromatography-tandem mass spectrometry. The results of material characterization tests confirmed the generation of magnetized COF. The adsorption process was optimized by Box-Behnken Design and one-factor optimization experiments. After five use cycles, Fe3O4/Tp-DHBD still achieved good adsorption and high recovery. Under the optimal conditions, the developed Fe3O4/Tp-DHBD COF-MSPE-HPLC-MS/MS method obtained good linearity for 12 OPEs within 0.25–50.0 ng mL−1 and the limit of detection of 0.02–0.18 ng mL−1. The relative standard deviations were less than 8.6 %. Rapid detection and analysis of three samples from wastewater treatment plant showed that the recoveries of most of target OPEs at different spiked concentrations ranged from 62.0 % to 116.9 %, 60.9 %-115.1 %, and 60.4 %-112.9 %, respectively. In general, the established COF-MSPE method can provide convenient and satisfactory purification for OPEs compounds in surface water by adsorption and desorption, which is promising for specific applications.

Synthesis of Fe3O4@SiO2-creatine as a new nanosorbent for dispersive magnetic solid-phase microextraction of copper ions from water, food, and soil samples

For the first time, Fe3O4@SiO2-creatine (Fe3O4@SiO2-CRT) was synthesized and exploited as a nanosorbent in the dispersive magnetic solid phase microextraction (D-MSPμE) of copper from water, food, and agricultural soil samples. Flame atomic absorption spectrometry was employed for the quantification of concentration of Cu(II) ions subsequent to the elution process. Different techniques, including X-ray diffraction, fourier transform infrared, field emission scanning electron microscopy, and vibrating sample magnetometer, were utilized to characterize the synthesized nanosorbent. The factors influencing the efficiency of the extraction process were investigated and optimized. Under the optimal conditions (solution pH, 7.0; nanosorbent quantity, 20 mg; adsorption time, 7.0 min; desorption time, 2.0 min; and desorption agent, HNO3 0.5 mol L−1), the proposed method provided a wide linear range (5.0–125 ng mL−1) with a determination coefficient (R2) of 0.9991. The limit of detection, extraction recovery, and relative recoveries were obtained to be 1.50 ng mL−1, 98.1%, and 90.6–103%, respectively. The intra-day relative standard deviation percentages (n = 5) for different concentrations were in the range of 2.33–3.11%. The proposed method offers merits such as swiftness, high sensitivity, rendering it applicable to detect trace levels of copper (5.19–14.2 ng mL−1 or ng g−1) in water, food, and agricultural soil samples.

Speciation of Chromium by Magnetic Solid Phase Microextraction Using an Activated Charcoal-Molybdenum (IV) Selenide-Magnetite Composite with Flame Atomic Absorption Spectrometric (FAAS) Detection

A simple and sensitive magnetic solid phase extraction (MSPE) method was developed for the separation-preconcentration and speciation of Cr in water samples. The system is based on the adsorption of Cr (VI)-ammonium pyrrolidinedithiocarbamate (APDC) complex on the activated charcoal@MoSe2@Fe3O4 composite. Total chromium has also been determined after the conversion of Cr (III) to Cr (VI) by oxidation with KMnO4. Cr (III) was determined as the difference between the total content of the Cr and Cr (VI). For quantitative recoveries, the effects of solution pH, adsorbent amount, volume of the sample, ligand volume, eluent type, and volume and effect of foreign ions were investigated. The limit of detection and limit of quantification for Cr was 0.36 ng mL−1 and 1.19 ng mL−1, respectively. The procedure was applied for the determination and speciation of chromium in water samples.

Green and efficient magnetic micro-solid phase extraction utilizing tea waste impregnated with magnetic nanoparticles for the analysis of ibuprofen in water samples by using UV-vis spectrophotometry.

A green method based on magnetic micro-solid phase extraction (MNP-TW-μ-SPE) of tea waste impregnated with magnetic nanoparticles (MNP-TW) was developed for the extraction of ibuprofen (IBP) in water samples prior to UV-Vis spectrophotometric analysis. Experimenting parameters that affect the extraction efficiency of IBP, such as pH of the sample solution, sorbent dosage, extraction time, ionic strength, volume of the sample, type of desorption solvent, desorption time, and desorption volume, were studied and optimized in detail. The characterization studies for the MNP-TW were carried out by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectrometry (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis, a vibrating sample magnetometer (VSM), and thermogravimetric analysis (TGA). Under the optimum conditions, the linearity ranges from 30 to 700 μg L-1 for IBP, with determination coefficients (R2) of 0.9983. The limit of detection (LOD) and limit of quantification (LOQ) were 9.40 μg L-1 and 28.50 μg L-1, respectively. The method also demonstrated good precision in reproducibility (RSD ≤ 1.53%), repeatability (RSD ≤ 1.48%), and recovery (86-115%). This method represents the advantages of low solvent consumption, flexibility, and better sensitivity compared to other studies employing spectrophotometric analysis. The usage of tea waste in the extraction process presents many advantages, as it is biodegradable, versatile, and contributes to an intelligent and sustainable economic strategy projected toward a circular economy approach.

Performance analysis and green profile assessment of synthesised amino-functionalised magnetic silica nanocomposite for magnetic micro-solid phase extraction of penicillin antibiotics from milk samples

This study explored the synthesis and application of amino-functionalised magnetic silica (Fe3O4 @mSiO2-NH2) nanocomposite as a selective sorbent for the extraction of penicillin antibiotics (PENs) from milk samples via magnetic micro-solid phase extraction (M-µ-SPE). The physicochemical characteristics of the synthesised sorbent were evaluated through important spectroscopy analyses. The adopted M-µ-SPE conditions were: 25 mg of Fe3O4 @mSiO2-NH2; pH 4; 3 min of extraction time; 1 min of desorption time; acetonitrile as the desorption solvent; 10% of salt addition; and 30 mL sample. Under the optimum conditions, the developed method demonstrated satisfactory from 10 to 500 µg/L (r2≥0.9986), low limits of detection (2.5–3.1 µg/L), high analytes recovery (85.2–106.7%), and good precision (RSDs≤8%,n = 5). The proposed method is rapid, simple, inexpensive, and shows good sensitivity when compared to previously developed methods. This study provides new insight into the development of a new sorbent for PENs and new microscale sample preparation for monitoring PENs in complex milk matrices.

Task specific microextraction column based on monolith for magnetic field-assisted in-tube solid phase microextraction of vanadium species in complex samples prior to online chromatographic analysis

The dominant species of vanadium (V) are V(IV) and V(V) which exhibit different toxicity and biological effects. Thus, speciation of V(IV) and V(V) is highly essential. Efficient sample preparation is the core step in the quantification of V(IV) and V(V). In the present study, a new task specific microextraction column based on monolith mingled with Fe3O4 nanoparticles (MBMC) was in situ synthesized in capillary and utilized as the extraction phase of magnetic field-assisted in-tube solid phase microextraction (MA-IT-SPME) of V(IV) and V(V) species which were coordinated with ethylene diamine tetraacetic acid (EDTA). The prepared MBMC presented porous and superparamagnetic properties, and possessed abundant functional groups. Results revealed that the exertion of magnetic field during adsorption and eluting steps boosted the extraction efficiency of V(IV)-EDTA and V(V)-EDTA chelates from 65.1 % to 55.7 %–90.0 % and 80.1 %, respectively. Under the beneficial extraction parameters, the established MA-IT-SPME was online hyphenated with HPLC/DAD to perform speciation of trace vanadium in water and vegetable samples, the achieved limits of detection were 0.054–0.060 μg/L and 1.4–1.5 μg/kg in water and vegetable samples, respectively, and the spiked recoveries varied from 82.5 to 118 %. In addition, relevant extraction mechanism under magnetic field was explored. In comparison with existing methods, the developed MA-IT-SPME technique displays some attractive merits such as automation, good anti-interference ability, high extraction efficiency, low cost and less use of organic solvent, in the capture of V species. The established online MBMC@MA-IT-SPME-HPLC/DAD system can become a competitive approach for sensitive speciation of V(IV) and V(V) at trace levels in complex samples.

Ruthenium nanoparticles encrusted with nitrogen & sulphur magnetic quantum dots as an efficient electrochemical sensor for simultaneous determination of itraconazole and terbinafine; a dual regimen for black fungus: Magnetic solid phase micro-extraction for urine and plasma analysis

After COVID-19 pandemic, Mucormycosis (black fungus) spreads as one of its related complications, due to the decrease in immunity system after administration of COVID-19 treatment drugs. A combination therapy of Itraconazole (ITR) and Terbinafine (TEB) was proved to be effective for treatment of black fungus. A novel electrochemical sensor was designed for estimation of ITR & TEB simultaneously by square wave voltammetric (SWV) technique. The sensor was fabricated using N&S-codoped magnetic quantum dots (N,S-MQDs) and ruthenium nanoparticles (Ru NPs). The fabricated sensor was characterized by cyclic voltammetry (CV), scanning electron microscope (SEM), powder X ray diffraction (pXRD), Fourier transform-Infrared (FT-IR), Raman spectroscopy and electrochemical impedance spectroscopy (EIS). Full optimization study for various experimental and instrumental parameters, in addition to method validation following International conference on Harmonization (ICH) guidelines was achieved. A good linearity in the range of 0.5–30 μg mL−1 with limit of detection (LOD) 0.24 and 0.19 μg mL−1 for ITR and TEB, respectively were obtained. The sensor was applied for analysis of ITR and TEB simultaneously in human plasma and urine samples without any interferences by applying dispersive magnetic solid phase micro-extraction (dMSPE) technique, where excellent recovery results exceeding 95 % were achieved.

An alginate-based eutectogel impregnated with polyvinylpyrrolidone/benzoic acid deep eutectic solvent and magnetic carboxylated multiwalled carbon nanotubes: Evaluated as sorbent in green microextraction of pesticides

This article presents the synthesis and application of a novel magnetic eutectogel constituting a polymeric deep eutectic solvent (PDES), carboxylated multiwall carbon nanotube (MWCNT-COOH), and super-dispersible/super-paramagnetic polyvinylpyrrolidone coated-Fe3O4 nanocrystals incorporated in alginate gel. Different methods were used for the characterization of novel polymeric based DES gel including FT-NMR, ATR-FTIR, and SEM were used. The novel DES eutectogel was used for the extraction of pesticides from honey. The modified eutectogel with PDES, MWCNT, and PDES-MWCNT showed 1.8-, 1.4-, and 2.5-fold enhancement in the sorption efficiency under green magnetic micro-solid-phase extraction (MSPE) method before GC–MS analysis. Important factors including the acidity of the samples, adsorption and desorption conditions, and the ionic strength of the preparation solution were investigated. The matrix effect, specificity, the quantification limits (0.023–1.023 μg kg−1), linear dynamic range (0.023–500 µg kg−1 with R2 of 0.9845–0.9986), relative standard deviations (<8.4%), were evaluated. In addition, the method was used to analyze 12 pesticides in four samples of honey. In the spiked concentration range of 0.1 to 10 μg kg-, the obtained recoveries were between 73.2 and 110.8% (RSD% = 8.1%, n = 3).

"Off/On" Fluorescent Probe based on Aggregation-Induced Quenching of ZnO-Quantum dots for Determination of Ara-C: Pharmacokinetic Applications, Adsorption Kinetics & Green Profile Assessment.

Herein, a turn "Off/On" fluorescence probe based on ZnO quantum dots (ZnO-QDs) has been proposed and successfully utilized for the determination of Ara-C (cytarabine) using ceric ions (Ce4+) as quencher and ethylenediamine (ED) as a linker. The probe is based initially on the quenching effect of Ce4+ ions on the strong native fluorescence of ZnO-QDs forming the Turn Off system (Ce@ZnO-QDs) that believed to occur due to the aggregation-induced quenching (AIQ) mechanism. The second step is the addition of Ara-C in the presence of ethylenediamine (ED) that encourages the formation of Ara-C/ED/Ce4+ as well as the release of the free ZnO-QDs, leading to the recovery of the fluorescence intensity. The developed sensing platform shows a linear response towards Ara-C over the range of 10 to 1000ngmL-1 giving a limit of detection (LOD) and limit of quantitation (LOQ) of 1.22ngmL-1 and 3.70ngmL-1, respectively. A dispersive magnetic solid phase micro-extraction (dMSPE) method was developed and optimized for the extraction of Ara-C in spiked human plasma using thiol-modified magnetite nanoparticles (S-MNPs). The proposed platform exhibits good sensitivity toward Ara-C in the presence of different interfering substances. Excellent recoveries are obtained after spiking different concentrations of Ara-C into rabbit plasma samples.The validated experimental parameters have been successfully applied to monitor the pharmacokinetic profile of Ara-C in rabbit plasma. A detailed adsorption kinetics study has been carried out to provide a deep insight into the adsorption behavior of Ara-C on the thiol-doped-magnetite nanoparticles. The greenness assessment of the proposed method was achieved and compared with other reported methods using two tools of greenness; the green analytical procedure index (GAPI) and the analytical greenness calculator AGREE.

Determination of Rhodamine B in Cosmetics, Candy, Water, and Plastic by a Novel Multiwalled Carbon Nanotube (MWCNT)@Zinc Oxide@Magnetite Nanocomposite for Magnetic Solid-Phase Extraction (MSPE) with Spectrophotometric Detection

A new magnetic solid phase microextraction method (MSPE) was developed for the preconcentration of rhodamine B from plastics, cosmetics, and environmental samples before spectrophotometric analysis. A nanocomposite adsorbent containing ZnO nanoparticles (NPs), multi-walled carbon nanotubes (MWCNTs) and Fe3O4 nanoparticles was synthesized by a hydrothermal procedure. The new magnetic nanocomposite (MWCNTs@ZnO@Fe3O4) was characterized by Fourier-transform infrared spectroscopy (FT-IR), x-ray diffraction (XRD), and scanning electron microscopy (SEM). The pH, sample volume, eluent type, adsorbent mass, influence of foreign species, and analyte-adsorbent and eluent contact times were optimized. The optimum pH was 3; adsorbent mass, 20 mg; sample volume, 50 mL; and eluent, 0.7 mL of ethanol. Recovery values exceeding 95% were obtained. The developed vortex assisted magnetic solid phase extraction method (VA-MSPE) was applied to practical analysis. The limits of detection (LOD) and quantification (LOQ) were 0.83 µg L−1 and 2.77 µg L−1, respectively. The addition/recovery experiments were carried on several water samples to demonstrate acceptable recoveries.

Magnetic Luffa@metal-organic frameworks (MOF-199) nanocomposite for the solid phase microextraction of some metal ions at trace levels from food and water samples

A new adsorbent (magnetic Luffa@MOF-199) was synthesized and used for magnetic solid phase microextraction for separation–preconcentration of Ni(II), Pb(II), Cr(III), and Cd(II) as 2-nitroso-2-naphthol chelates prior to their flame atomic absorption spectrometer (FAAS) detection. Analytical parameters that affect the quantitative recoveries of analytes such as pH, adsorbent amount, sample and eluent volumes, adsorption and desorption time, and eluent type were optimized. The impact of foreign ions was investigated. The limits of quantification (LOQ) values were 0.35 μg L-1 for Ni(II), 0.38 μg L-1 for Pb(II), 0.55 μg L1- for Cr(III) and 0.12 μg L-1 for Cd(II). The relative standard deviations (RSD) were in the range of 3.4 – 6.0%. The developed method was validated using certified reference materials (CRMs) (TMDA-64.3 fortified water, GBW07424 (GSS-10) soil and 1573a Tomato Leaves). The method was applied to determination of Ni(II), Pb(II), Cr(III), and Cd(II) contents of some food, tobacco, and wastewater samples.

Selective and fast magnetic dispersive solid phase micro-extraction of copper and lead in water and vegetables after synthesis of magnetic mesoporous carbon

Magnetic mesoporous carbon (Fe3O4@C, MMC) was synthesized and characterized. It was used for the first time as a sorbent for the magnetic dispersive solid phase microextraction (M-dSPμE) of copper and lead in water and vegetables. FAAS was used to determine the analyte concentrations after elution. The MMC was found to be have surface area of 145.9 m2 g−1 and average pore diameter of 15 nm. The analytical parameters affecting M-dSPμE of copper and lead were optimized. They were pH of sample, 6; eluent, 2 mol L−1 HCl (3 mL); and sample volume, 250 mL. The MMC reaches equilibrium very fast without vortexing for adsorption and only 5 s for elution. The LOD and PF of the M-dSPμE method for copper and lead were found to be 0.87 μg L−1 and 83 for Cu(II) and 2.8 μg L−1 and 167 for Pb(II), respectively. The precision of the M-dSPμE method was found to be ≤ 3.2%. The M-dSPμE method was verified by certificate reference materials (TMDA-53.3 Fortified Lake water and NIST SRM 1573a Tomato Leaves). It was successfully applied to the determination of copper and lead in lake water, wastewaters, sea water, radish, spinach, lettuce, and celery samples.

Polyamidoamine with a hyper-branched structure grafted on modified magnetic graphene oxide for the trace separation of diclofenac and acetaminophen followed by high-performance liquid chromatography determination

Different generations of polyamidoamine dendrimers were synthesized on a focal core of magnetic graphene oxide modified with 3-aminopropyltriethoxysilane. After the characterization of synthesized dendrimers, its second generation was employed as a suitable sorbent for simultaneous separation/preconcentration of diclofenac and acetaminophen by a dispersive magnetic solid phase microextraction. The extracted analytes were then quantified by high-performance liquid chromatography with ultraviolet detection. Under optimized conditions, the limits of detection were 0.3 µg/L for diclofenac and 0.1 µg/L for acetaminophen. The intra-day relative standard deviations at 50 μg L−1 levels were 1.8% for diclofenac and 2.1% for acetaminophen, while the inter-day relative standard deviations were 3.6% and 4.5% for diclofenac and acetaminophen, respectively. The calibration graphs were linear in ranges of 1.0–500.0 µg/L and 0.5–600.0 µg/L for diclofenac and acetaminophen, respectively, with good coefficients of determination (r2 > 0.998). The method was successfully applied to the determination of diclofenac and acetaminophen in water, milk, and biological samples.

Potential of cobalt ferrite-graphitic carbon nitride nanocomposite in trace determination of pyrene as one of the priority pollutants in water and food samples

In this research, cobalt ferrite-graphitic carbon nitride (CoFe2O4/GC3N4) nanocomposite with high extraction ability, high sensitivity, and strong magnetic properties was successfully synthesized and evaluated as a sorbent for ultrasound-assisted dispersive magnetic micro-solid phase extraction (UA-DM-μ-SPE) of pyrene (Py) in food and water samples. A successful synthesis of CoFe2O4/GC3N4 was inspected by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), energy-dispersive X-ray spectrometry (EDXS), and vibrating sample magnetometer (VSM) techniques. The experimental parameters affecting the UA-DM-μ-SPE efficiency, such as the amount of sorbent, pH, adsorption time, desorption time, and temperature, were effectively investigated according to a multivariate optimization approach. Under the optimal conditions, the detection limit, quantification limit, and relative standard deviation (RSD) for the target analyte were achieved at 2.33 ng mL−1, 7.70 ng mL−1, and 3.12%, respectively. The CoFe2O4/GC3N4 based UA-DM-μ-SPE followed by spectrofluorometry confirmed favorable results for the convenient and efficient determination of Py in the samples of vegetable, fruit, tea, and water.

Magnetic Solid-Phase Microextraction Protocol Based on Didodecyldimethylammonium Bromide-Functionalized Nanoparticles for the Quantification of Epirubicin in Biological Matrices.

Due to epirubicin's (EPI) narrow therapeutic index and risk of cardiotoxicity, it is critical to monitor concentrations of this drug when being used to treat cancer patients. In this study, a simple and fast magnetic solid-phase microextraction (MSPME) protocol for the determination of EPI in plasma and urine samples is developed and tested. Experiments were performed using prepared Fe3O4-based nanoparticles coated with silica and a double-chain surfactant-namely, didodecyldimethylammonium bromide (DDAB)-as a magnetic sorbent. All the prepared samples were analyzed via liquid chromatography coupled with fluorescence detection (LC-FL). The validation parameters indicated good linearity in the range of 0.001-1 µg/mL with a correlation coefficient > 0.9996 for plasma samples, and in the range of 0.001-10 µg/mL with a correlation coefficient > 0.9997 for urine samples. The limit of detection (LOD) and limit of quantification (LOQ) for both matrices were estimated at 0.0005 µg/mL and 0.001 µg/mL, respectively. The analyte recovery after sample pretreatment was 80 ± 5% for the plasma samples and 90 ± 3% for the urine samples. The developed method's applicability for monitoring EPI concentrations was evaluated by employing it to analyze real plasma and urine samples collected from a pediatric cancer patient. The obtained results confirmed the proposed MSPME-based method's usefulness, and enabled the determination of the EPI concentration-time profile in the studied patient. The miniaturization of the sampling procedure, along with the significant reduction in pre-treatment steps, make the proposed protocol a promising alternative to routine approaches to monitoring EPI levels in clinical laboratories.

Separation and Preconcentration of Atrazine on Magnetic Multiwalled Carbon Nanotubes before Determination in Food and Water Samples by High-Performance Liquid Chromatography with Diode Array Detection (HPLC-DAD)

This work focuses upon the easy and efficient synthesis of multi-walled carbon nanotubes (MWCNT) decorated with magnetite used in the vortex-assisted magnetic solid-phase microextraction (VA-m-µ-SPE) of atrazine in water and food samples. The nanocomposite was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and infrared spectroscopy. Parameters that influenced VA-m-µ-SPE (pH, mMWCNT mass, extraction time, eluent type and volume, and sample volume) were optimized. The presented technique provided a preconcentration factor of 10-fold with limits of detection and quantification of 2.1 μg L−1 and 6.4 μg L−1, respectively, and a linear range from 12.5 to 250 μg L−1. VA-m-µ-SPE has been applied in the preconcentration and determination of atrazine in the natural waters. In addition, atrazine was determined in ginger and fennel.

Development of clinoptilolite zeolite-coated magnetic nanocomposite-based solid phase microextraction method for the determination of Rhodamine B in cosmetic products

Green synthesis of clinoptilolite zeolite/Fe3O4 nanocomposite (MZNC) was carried out using Laurus Nobilis L. leaf extract. Characterization of this MZNC was performed using Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, X-Ray Diffraction and Vibrating Sample Magnetometer. According to the VSM analysis results, the saturation magnetization of 23 emu/g and coercivity of 23.5 Oe indicate that the synthesized magnetic nanocomposite is superparamagnetic. A new ultrasonic assisted clinoptilolite zeolite-coated magnetic nanocomposite-based solid phase microextraction (MZNC-SPME) method combined with high performance liquid chromatography was developed for the extraction and determination of Rhodamine B. The preconcentration factor for the MZNC-SPME method was found to be 40 under optimal conditions. Under optimal conditions, the linear range, correlation coefficient (R2), limit of detection (LOD), and intra- and interday relative standard deviation (RSD) were found to be 1.00–100.00 ng mL−1, 0.9995, 0.16 ng mL−1, 1.89% and 2.49%, respectively. The developed method was successfully performed to determine Rhodamine B in 6 different cosmetic samples. 6 ions and 5 different dyes were added to the sample solution to show the selectivity of the method. The obtained results show that the determination of Rhodamine B is possible in the presence of these ions and dyes. In order to determine the accuracy of the MZNC-SPME method, two different concentrations of Rhodamine B concentration in cosmetic samples were added as 10 and 50 ng mL−1. Extraction recoveries were found in the range of 92.03-101.52% and these results are quite satisfactory. It is seen that the developed method for the extraction and determination of Rhodamine B from cosmetic samples is applicable due to the easy synthesis of the sorbent and the short, simple, environmentally friendly and low cost of the method.

Enhanced adsorption/extraction of bisphenols by pyrrolic N-based 3D magnetic carbon nanocomposites for effervescence-assisted solid-phase microextraction of bisphenols from juices and the underlying interaction mechanisms

Herein, we fabricated a magnetic 3D nanocomposite based on Co,Ni-codoped and N-modified carbon nanotubes and reduced graphene (CoNi-N-CNTs/rGO). This nanomaterial possessed strong magnetism due to the presence of Co-Ni alloy, abundant defect sites owing to N doping, and a 3D multi-porous structure resulting from CNT in-situ growth on the graphene surface. Based on DFT calculations, H-bonding, hydrophobic and π-π conjugation were inferred to facilitate bisphenol adsorption by nanocomposites, among which π-π interactions provided the greatest adsorption contribution within a given N-doping type. By employing BPM as model compound, the adsorption energies (ΔEa) for π-π conjugation were −1.80, −1.59 and −2.08 eV for graphitic-N, pyridinic-N, and pyrrolic-N, respectively. This infers that pyrrolic-N sites form the strongest BP sorption bonds with the nanocomposite. The nanocomposites were utilized as an extractant in an effervescence tablet-assisted magnetic solid-phase microextraction (ET-MSPE) procedure that was optimized using Plackett-Burman design (PBD) and central composite design (CCD). Under optimized conditions, the ET-MSPE/HPLC-FLD method provided strong analytical performance for quantification of six BPs in juice with limits of detection of 0.06–0.20 μg/L, recoveries of 82.4–103.7 % and RSDs of 1.2–5.3 %. The particular novelty of this study lies in demonstrating the enhancement of adsorption/extraction efficiencies for BPs by nanocomposites resulting from N doping to generate the superior adsorption properties associated with the pyrrolic-N structure. These findings provide a theoretical foundation to inform the rational design of N-doped adsorbents/extractants based on a rigorus understanding of the molecular interactions occurring between carbon-based nanocomposites and BP analogues.