Magnetic Dispersive Solid-phase Extraction Research Articles

β-Cyclodextrin-grafted magnetic graphene oxide nanocomposites in ultrasound-assisted dispersive magnetic solid-phase extraction for simultaneous preconcentration of lead and cadmium ions

This article presents an ultrasound-assisted dispersive magnetic solid-phase extraction method (USA-DMSPE) to preconcentration Cd(II) and Pb(II) simultaneously. The adsorbent (mGO-βCD) was synthesized through three steps with consumption of environmentally friendly materials at room temperature. First graphene oxide (GO) was prepared via modified Hummer’s method and then magnetized by Fe3O4 precipitation (mGO). Finally, β-cyclodextrin was covalently immobilized onto the surface of mGO. X-ray diffraction patterns established pure crystallinity of the materials. Homogenous distribution of magnetic nanoparticles onto GO sheets was confirmed by scanning electron microscopy and transmission electron microscopy. FT-IR spectra proved successful modification of mGO by β-CD. Alternating gradient force magnetometer characterized magnetic property. Brunauer–Emmett–Teller showed porous structure of mGO-βCD and having high surface area. pH (7 ± 0.2), adsorption time (2 min), adsorbent amount (20 mg), eluent kind (HNO3 (3 ml of 2.0 mol L−1)) and desorption time (one minute) were optimum conditions. Sonication disperses adsorbent in sample solution, which accelerates mass transfer, as well as decreasing adsorption time and adsorbent usage amount. Applicability of the method was investigated according to preconcentration factor (Pb(II): 200 and Cd(II): 167), linearity of dynamic range (Pb(II): (2–410) and Cd(II) (3–400 μg L−1), limit of detection (Pb(II): 0.64 and Cd (II): 0.9 μg L−1), relative standard deviation (Pb(II): 1.68% and Cd(II): 2.51%) and adsorption capacity (Pb(II): 188.68 and Cd(II): 78.12). mGO-βCD was reusable for ten times and durable in six months. Selectivity and effect of interference ions were reported. Obtained recoveries for real samples verified the satisfactory performance of the method.

The enrichment and extraction of parabens with polydopamine-coated microporous carrageenan hydrogel beads incorporating a hierarchical composite of metal-organic frameworks and magnetite nanoparticles

A polydopamine-coated microporous composite of metal–organic frameworks and magnetite nanoparticles embedded in carrageenan hydrogel beads was fabricated and successfully utilized for the dispersive magnetic solid-phase extraction of parabens. Polydopamine and the metal organic frameworks enhanced the adsorption of parabens on the hierarchical composite sorbent by hydrogen bonding, hydrophobic and π-π interactions. The affecting parameters were optimized to achieve the highest extraction efficiency from rapid extraction with low solvent consumption. The developed method provided linearity from 0.10 to 100 µg L-1 of methyl parabens, 0.50–100 µg L-1 of ethyl paraben and 2.0–100 µg L-1 of propyl parabens and butyl paraben with low limit of detection (0.05–1.0 µg L-1). When used to extract parabens in real samples, the composite adsorbent showed good accuracy, achieved extraction recoveries in the range of 80 to 96% and had a good stability which enabled reuse. The proposed hierarchical composite adsorbent could potentially be altered for the extraction of other compounds in various matrices.

Magnetic Mesoporous Carbon/β-Cyclodextrin-Chitosan Nanocomposite for Extraction and Preconcentration of Multi-Class Emerging Contaminant Residues in Environmental Samples.

This study reports the development of magnetic solid-phase extraction combined with high-performance liquid chromatography for the determination of ten trace amounts of emerging contaminants (fluoroquinolone antibiotics, parabens, anticonvulsants and β-blockers) in water systems. Magnetic mesoporous carbon/β-cyclodextrin–chitosan (MMPC/Cyc-Chit) was used as an adsorbent in dispersive magnetic solid-phase extraction (DMSPE). The magnetic solid-phase extraction method was optimized using central composite design. Under the optimum conditions, the limits of detection (LODs) ranged from 0.1 to 0.7 ng L−1, 0.5 to 1.1 ng L−1 and 0.2 to 0.8 ng L−1 for anticonvulsants and β-blockers, fluoroquinolone and parabens, respectively. Relatively good dynamic linear ranges were obtained for all the investigated analytes. The repeatability (n = 7) and reproducibility (n = 5) were less than 5%, while the enrichment factors ranged between 90 and 150. The feasibility of the method in real samples was assessed by analysis of river water, tap water and wastewater samples. The recoveries for the investigated analytes in the real samples ranged from 93.5 to 98.8%, with %RSDs under 4%.

Simple and efficient method for the determination of Cr(VI) ions in water samples using m-MWCNT@APTMS through dispersive magnetic solid phase extraction

ABSTRACT This work describes the synthesis and characterisation of a promising adsorbent nanocomposite based on magnetic multiwalled carbon nanotubes (m-MWCNTs) functionalised with 3-aminopropyltrimethoxysilane (APTMS). Was developed a method based on dispersive magnetic solid phase extraction (DMSPE). It also details its use in the development of a rapid and simple preconcentration method for Cr(VI) ions in water samples with FAAS detection. The nanocomposite was characterised using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM); the textural data measurements were obtained using the Brunauer-Emmett-Teller (BET) and Barret-Joyner-Halenda (BJH) analyses. The maximum adsorption capacity of the m-MWCNT@APTMS nanocomposite for Cr(VI) ions was 13.37 mg g-1 at an equilibrium time of 20 min. The adsorption process followed the dual-site Langmuir-Freundlich model, while the kinetic data were well fitted by the pseudo-second-order model. The important variables that affect the performance of the MSPE method, such as the pH of the sample, adsorbent mass, preconcentration and elution time, and type of eluent were univariately optimised. Under the optimised condition, an aliquot of 20 mL of sample was preconcentrated using 40 mg of m-MWCNT@APTMS for 4 min under vortex agitation. After this, the nanoparticles were separated from the solution with a magnet, then, the adsorbed Cr(VI) ions in the adsorbent were eluted with 1.0 mL of 2.0 mol L-1 HNO3 for 1.0 min and submitted to FAAS detection. The linear range studied was of 0.02 -0.2 mg L-1. When the enrichment factor was 20, the LOD and LOQ to Cr(VI) ions were 3.18 and 10.7 µg L-1, respectively, presenting RSD of 0.18% and 0.28% for solutions of Cr(VI) at 0.08 mg L-1 and 0.18 mg L-1. Finally, the proposed method was applied for the speciation of Cr(VI) in water samples and the results were compared with reference technique (GF AAS).

Accurate and sensitive determination of cobalt in urine samples using deep eutectic solvent-assisted magnetic colloidal gel-based dispersive solid phase extraction prior to slotted quartz tube equipped flame atomic absorption spectrometry

In this study, a colloidal gel of magnetic Fe3O4 nanoparticles was used in the development of a simple and accurate dispersive solid phase extraction method for the extraction/preconcentration of trace levels of cobalt ions in urine samples. The eluted cobalt ions were determined by slotted quartz tube-flame atomic absorption spectrophotometry (SQT-FAAS). The effects of the type and volume of buffer solution, volume of magnetic colloidal gel, type and period of mixing, concentration and volume of the eluent were investigated and optimized to obtain the best experimental outputs. Under the optimum conditions, the limits of detection and quantification were found as 4.6 and 15 ng mL−1, respectively. The developed method provided a 61.5 folds enhancement in the detection power of the flame atomic absorption spectrophotometry. Method validation was performed by spiking experiments using matrix matching method. The percent recoveries were found to be close to 100% for the spiked samples, which validate the accuracy and the applicability of the developed method to the urine samples.

Gelatin microsphere coated Fe3O4@graphene quantum dots nanoparticles as a novel magnetic sorbent for ultrasound-assisted dispersive magnetic solid-phase extraction of tricyclic antidepressants in biological samples.

Gelatin microsphere-coated Fe3O4@graphene quantum dots (Fe3O4@GQD@GM) were designed and synthesized as a novel sorbent via ultrasonic-assisted dispersive magnetic solid-phase extraction (UA-DMSPE) method. The synthesized sorbent was identified and confirmed by FT-IR, XRD, VSM, and SEM techniques. UA-DMSPE was combined with corona discharge ion mobility spectrometry for trace determination of desipramine, sertraline, and citalopram. Effective parameters were considered and optimized. The proposed method, under optimal conditions, showed excellent linearity in different concentration ranges (2-700ng mL-1, R2 > 0.995), repeatability (RSD < 5.1%), good sensitivity (LODs in the range 0.6-1.5ngmL-1), high preconcentration factor (PF = 207-218), and acceptable relative recoveries (93.5-101.8%). Eventually, this method was used to determine tricyclic antidepressants in various biological samples. Schematic presentation of the microextraction and monitoring of TCAs by ultrasonic-assisted dispersive magnetic solid phase microextraction-ion mobility spectrometry producer.

Cellulose-ferrite nanocomposite for monitoring enniatins and beauvericins in paprika by liquid chromatography and high-resolution mass spectrometry

Paprika is considered a high-quality product being one of the most consumed spices in the world. Contamination with mycotoxins may appear due to inappropriate practices during processing or resulting from invading mould in the final manufactured products. A sample treatment based on dispersive magnetic solid-phase extraction (DMSPE) has been proposed for emerging mycotoxin determination, enniatins (ENNs) and beauvericins (BEAs), in paprika. Different magnetic nanoparticles were tested, and cellulose-ferrite nanocomposite was selected for the extraction and preconcentration of the mycotoxins. Nanocomposite was characterised using field emission scanning electron microscopy and energy dispersive X-ray spectroscopy in terms of morphology and elemental composition. High-resolution mass spectrometry allowed the quantification of the five main emerging mycotoxins and the monitoring of unexpected members of this class of toxic fungal secondary metabolites. The method has been validated, obtaining limits of quantification between 9.5 and 9.9 μg kg−1 and testing its trueness through recovery studies, with satisfactory values of between 89.5 and 97.7%. Relative standard deviations were calculated to evaluate the intra- and inter-day precision and values lower than 8% were obtained in all cases. The analysis of 26 samples, including conventional and organic, demonstrated the presence of ENNB1 at 12.0 ± 0.6 μg kg−1 in one of the samples studied. Other analogues ENNs and BEAs were not detected.

3D flower-liked Fe3O4/C for highly sensitive magnetic dispersive solid-phase extraction of four trace non-steroidal anti-inflammatory drugs.

A low cost-effective and simple synthesis method was adopted to acquire three-dimensional flower-like structure Fe3O4/C that has large specific area, suitable pore structure and sufficient saturation magnetism. The obtained Fe3O4/C exhibits outstanding preconcentration ability andwas applied to extracting non-steroidal anti-inflammatory drugs from complex environmental and biological samples. The parameters of magnetic solid-phase extraction were optimized by univariate and multivariate methods (Box-Behnken design). The high degree of linearity from 2.5 to 1000.0ngmL-1 (R2≥ 0.9976), the limits of detection from 0.25 to 0.5ngmL- 1 (S/N= 3), and the limits of quantitation from 1.0 to 2.0ngmL- 1 (S/N= 10) were yielded by adopting this novel method after the optimization. Moreover, the recoveries of non-steroidal anti-inflammatory drugs from 89.6 to 107.0% were acquired in spiked plasma, urine and lake samples. In addition, the adsorption of non-steroidal anti-inflammatory drugs on Fe3O4/C was explored by adsorption isotherms and kinetic studies. Furthermore, the adsorption mechanism for non-steroidal anti-inflammatory drugs by Fe3O4/C was proposed, which was hydrogen bonding and π-π interaction between non-steroidal anti-inflammatory drugs and Fe3O4/C. Graphical abstract.

Development of a Stirring-Dependent Magnetic Dispersive Solid Phase Extraction Method Coupled with Ferrofluid-Based Dispersive Liquid–Liquid Microextraction for the Extraction of Some Pyrethroid Pesticides from Fruit Juices

In the present work, a new and efficient sample treatment method based on the combination of stirring-dependent magnetic dispersive solid phase microextraction and ferrofluid-based dispersive liquid–liquid microextraction has been developed for the extraction of some pyrethroid pesticides (bifenthrin, phenothrin, tetramethrin, cyhalothrin, permethrin, and cypermethrin) from fruit juices prior to their determination with gas chromatography–mass spectrometry. For this purpose, a few milligrams of a synthesized magnetic sorbent (Fe3O4@polythiophene) is added into a sample solution containing the analytes and stirred at high rate. By this action, particles of the magnetic sorbent are detached from the magnetic stir bar surface and completely dispersed throughout the solution. After stopping stirring, the particles containing the adsorbed analytes are rapidly returned onto the stir bar. Then, the stir bar is taken and eluted with an appropriate solvent to desorb the analytes. Afterward, the eluent is mixed with a few microliters of a synthesized ferrofluid and the mixture is rapidly injected into deionized water placed in a conical glass test tube for more enrichment of the analytes. In the next step, the ferrofluid settled down at the bottom of the tube in the presence of an external magnet and the supernatant is discarded. After back-extraction of the analytes with n-hexane, an aliquot of the extract is injected into the determination system. Under optimal conditions, the developed method offered high enrichment factors (1380–1660) and extraction recoveries (69–83%), and low limits of detection (4.0–12 ng L−1) and quantification (14–40 ng L−1). The relative standard deviations were ≤ 7.1% for intra-day (n = 6) and inter-day (n = 4) precisions at a concentration of 250 ng L−1 of each analyte. Finally, six different fruit juice samples were successfully analyzed by the introduced method and cypermethrin was detected in apple juice at a concentration of 110 ± 0.5 ng L−1.

Magnetic Dispersive Solid Phase Extraction Using Recycled-graphite for GO-Fe3O4-dithizone Composite Combined with FAAS for Determination of Lead in Environmental Samples.

Magnetic dispersive solid phase extraction (MdSPE) was developed to determine the concentration of lead (Pb) in real water samples, while graphene oxide-magnetite-dithizone (GO-Fe3O4-DTZ) from the used graphite tubes (recycled graphite) of electrothermal technique was simply employed as a new sorbent to improve extraction efficiency, separated by external magnetic field and analyzed with FAAS. The synthesized sorbent was evaluated for its surface property, functional group and surface morphology by Zeta potential, Fourier transform infrared spectrophotometer (FTIR), and scanning electron microscope (SEM), respectively. The relevant measurement parameters, such as pH, extraction time, type and concentration of eluent, sample volume and reusability, were optimized. Under the optimal conditions, preconcentration factor was 13.33. The limit of detection (LOD) and limit of quantitation (LOQ) obtained were 0.070 and 0.23 mg/L, respectively. The relative standard deviation (%RSD) was 3.41%. Recovery values were 90.1 - 123%. In addition, the robustness of the method was affirmed in terms of tolerance limit obtained from interference studies.

Rapid quantitation of three synthetic cathinones in urine by magnetic dispersive solid-phase extraction combined with DART-HRMS.

For the rapid quantitation of three synthetic cathinones, namely 1-(4-chlorophenyl)-2-(1-pyrrolidinyl)pentan-1-one (4-Cl-α-PVP), 1-(4-methylphenyl)-2-(methylamino)pentan-1-one (4-MPD), and 1-(5,6,7,8-tetrahydronaphthalen-2-yl)-2-(1-pyrrolidinyl)pentan-1-one (β-TH-naphyrone), in urine, a new method was established using magnetic dispersive solid-phase extraction (MDSPE) combined with direct analysis in real time and high-resolution mass spectrometry (DART-HRMS). Methcathinone-D3 and proadifen (SKF525A) were used as the internal standards. Hydrophobic magnetic adsorbents were used and consisted of hydrophobic functional group (divinylbenzene) and hydrophilic functional group (vinylpyrrolidone) at a ratio of 3 : 1, and NaH2PO4//NaOH buffer (0.2 M, pH 7) was used in MDSPE. Detection was conducted by DART-HRMS in less than 1 min. For 4-Cl-α-PVP, 4-MPD and β-TH-Naphyrone, the limits of detection were 0.1 ng mL-1, 0.05 ng mL-1 and 0.1 ng mL-1, and the linear ranges were 0.5-100 ng mL-1, 0.2-100 ng mL-1 and 0.2-100 ng mL-1, respectively. The correlation coefficients were all greater than 0.99. The precision and deviation of accuracy were all within ±15%, and the stability of the samples was high under various conditions. The method was successfully applied to detect 4-Cl-α-PVP, 4-MPD and β-TH-naphyrone in rat urine after subcutaneous administration. In summary, a fast and convenient detection method was established, providing new and effective technical support for the rapid quantitation of three synthetic cathinones (4-Cl-α-PVP, 4-MPD and β-TH-Naphyrone) for forensic purposes.

Determination of sulfonamide residues in animal foodstuffs by magnetic dispersive solid-phase extraction using magnetic carbon nanocomposites coupled with ion pair-dispersive liquid\u2013liquid micro-extraction combined with HPLC-DAD

In this study, magnetic-dispersive solid-phase extraction coupled with ion pair-dispersive liquid–liquid micro-extraction (MSPE-i-DLLME) was used to the pre-concentration and extraction of five sulfonamides residues (sulfadiazine, sulfathiazole, sulfacetamide, sulfamethazine and sulfamethoxazole) in animal foodstuffs. The sulfonamides are extracted using magnetic carbon nanocomposite and then eluted with acetonitrile. In the DLLME step, the target analytes are collected in 1-octanol containing 10% Aliquat-336 (as extraction solvent). Finally, the compounds are quantified by HPLC with DAD detection. The extraction parameters optimized using the one at the time and central composite design methods. Under the optimized conditions: sample solution volume was 100 mL; initial pH: 12, amounts of MCNs: 30 mg; desorption solvent (ACN) volume, 1 mL; desorption condition, 10 min sonication at two step; extraction solvent (1-octanol + 10% aliquat) volume, 115 µL; pH of DLLME step, 3; salt effect, 24.6%, (w/v) NaCl; centrifuge, 5 min, 4000 rpm. In these extraction conditions, the proposed procedure represented good pre-concentration factors between 130 and 490; detection limits in the range from 0.01 to 5 μg kg−1 (at S/N = 3), and linear response in the 0.1–400 μg kg−1 concentration range. The method is successfully applied to the determination of sulfonamides residues in animal foodstuffs.

Speciation and Enrichment of Cadmium and Lead from Water Samples using Fe3O4/rGO Sorbent in Dispersive Magnetic Micro-Solid Phase Extraction with Inductively Coupled Plasma-Optical Emission Spectroscopy

This work reports the development of dispersive magnetic solid-phase extraction (DMSPE) with high resolution ICP-OES for the pre-concentration of cadmium and lead in water samples. The method uses magnetic reduced graphene oxide (Fe3O4/rGO) as adsorbent. The influences of sample pH, extraction time, desorption solvent and desorption time were evaluated and optimized. In the optimized conditions, linear calibration curves for Cd2+ and Pb2+ were obtained in the range of 10-2000 μg L-1 with correlation coefficients of 0.9996 and 0.9995, respectively. Low detection limits of Cd2+ and Pb2+ were found to be 9.03 μg L-1 and 12.4 μg L-1, respectively. Good relative recovery values, in the range of 91-95% and excellent repeatability of 6.4-9.9%, (n = 3) were obtained. The results revealed that Fe3O4/rGO can be a suitable nanocomposite sorbent in the speciation and pre-concentration of Cd2+ and Pb2+ for tap water and drinking water samples. The method is rapid, selective, reliable and environmentally friendly for the determination of Cd2+ and Pb2+ in water samples.

Sensitive determination of mercury by magnetic dispersive solid-phase extraction combined with flow-injection-cold vapour-graphite furnace atomic absorption spectrometry

The preconcentration of Hg through MDSPE and cold vapor (CV) resulted in an excellent LOD.

Fabrication of ZIF-71/Fe3O4/polythionine nanoarray-functionalized carbon cotton cloth for simultaneous extraction and quantitation of febuxostat and diclofenac

A sustainable hybrid material based on carbonized cotton cloth/zeolite imidazolate framework-71/Fe3O4/polythionine (CC/ZIF-71/Fe3O4/PTh) was synthesized and applied in ultrasound-assisted dispersive magnetic solid-phase extraction (USA-DMSPE) followed with high performance liquid chromatography-ultraviolet detection (HPLC-UV) for simultaneous quantitation of diclofenac (DIC) and febuxostat (FEB) in human plasma. The surface of CC was modified with nanoarrays of zeolite imidazolate framework-71/Fe3O4/Polythionine. At first, an in situ synthesis of ZIF-71 in the presence of CC was carried out, and followed with magnetization process and oxidative polymerization of thionine. The nano-modifier agents improved the merits of the sorbent involving stability, porosity, mast transfer, π–π interactions and selectivity of CC. Characterizations of the hybrid sorbent were examined with different instrumental techniques. The limits of detection (LODs, S/N = 3) were recognized 2.1 ng mL−1 for DIC and 3.7 ng mL−1 for FEB. Acceptable linearity (0.992 ≤ r2 ≤0.996) and relatively broad dynamic ranges of 10.0–1800.0 ng mL−1 and 15.0–2500.0 ng mL−1 were achieved for DIC and FEB, respectively. Reasonable intra-assay (≤7.2%, n = 9) and inter-assay (≤7.5%, n = 9) precisions as well as appropriate accuracies (≤8.0%) were provided illustrating applicability of the current approach for analytical purposes. Eventually, CC/ZIF-71/Fe3O4/PTh was employed as four-part sorbent for the assessment of DIC and FEB in human plasma at trace levels and subsequently main pharmacokinetic data such as T1/2, Tmax,Cmax, and AUC0–24 of these drugs were comprehensively investigated.

Magnetic Ti3C2 MXene functionalized with β-cyclodextrin as magnetic solid-phase extraction and in situ derivatization for determining 12 phytohormones in oilseeds by ultra-performance liquid chromatography-tandem mass spectrometry

Magnetic solid phase extraction integrated with in situ derivations for the profiling of 12 phytohormones in a single rapeseed seed was developed by using ultra-high performance liquid chromatography-tandem mass spectrometry. The Fe3O4@Ti3C2@β-cyclodextrin nanoparticles were firstly synthesized and used as an adsorbent for the solid-phase extraction of phytohormones. The magnetic dispersive solid-phase extraction and in situ derivation by the addition of N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide were ingeniously combined. This efficient pre-treatment method integrated the extraction, purification, and derivatization processes into one single step. Satisfactory methodological performance was achieved by optimization of the parameters. Linearities (R2 > 0.9928) and recoveries (80.4 %–115.1%) at three spiked levels, as well as the low matrix effect (from −16.63% to 17.06%) and limits of detection (0.89–13.62 pg/mL) were obtained. The spatio-temporal profiling of target phytohormones in different tissues of rapeseed germination was investigated. This method was successfully employed for analyzing target phytohormones in different oilseeds samples.

Insights into the structure-performance relationships of extraction materials in sample preparation for chromatography

Sample preparation is one of the most crucial steps in analytical processes. Commonly used methods, including solid-phase extraction, dispersive solid-phase extraction, dispersive magnetic solid-phase extraction, and solid-phase microextraction, greatly depend on the extraction materials. In recent decades, a vast number of materials have been studied and used in sample preparation for chromatography. Due to the unique structural properties, extraction materials significantly improve the performance of extraction devices. Endowing extraction materials with suitable structural properties can shorten the pretreatment process and improve the extraction efficiency and selectivity. To understand the structure-performance relationships of extraction materials, this review systematically summarizes the structural properties, including the pore size, pore shape, pore volume, accessibility of active sites, specific surface area, functional groups and physicochemical properties. The mechanisms by which the structural properties influence the extraction performance are also elucidated in detail. Finally, three principles for the design and synthesis of extraction materials are summarized. This review can provide systematic guidelines for synthesizing extraction materials and preparing extraction devices.

Magnetic solid phase extraction followed by in-situ derivatization with core-shell structured titanium dioxide coated ferriferrous oxide microspheres for determination of alendronate in plasma

In this study, for the first time, magnetic solid phase extraction (MSPE) was combined with in-situ derivatization to determine alendronate in plasma. TiO2 coated Fe3O4 microspheres (denoted as Fe3O4@TiO2) were synthesized via polydopamine coating, titanium ions immobilizing and calcination steps. The as-prepared microspheres could selectively extract alendronate and be quickly isolated from plasma. The drug-adsorbed Fe3O4@TiO2 microspheres were then directly incubated in derivatization reagent solution to perform novel in-situ derivatization and elution procedure, in which the derivatized alendronate lost its affinity to TiO2 and was spontaneously eluted for further LC-MS/MS detection. Satisfactory results were obtained on the creative attempt to couple dispersive magnetic solid phase extraction with in-situ derivatization. The developed method was validated and demonstrated good linearity (0.05-500 ng mL−1), low detection limit (20 pg mL−1), great accuracy (100.6% to 105.3%) and precision (RSDs<5.27%). Manual operation and analysis time could be greatly reduced compared to other reported methods. The method was successfully applied to a pharmacokinetic study in beagle dogs.

Comparison of two polythiophene nanocomposites-based dispersive micro solid-phase extraction procedures coupled with salt-induced/magnetic separations for efficient preconcentration of toxic metal ions from food samples

For the first time, the polythiophene nanocomposite-based air-agitated dispersive micro solid-phase extraction coupled with salt-induced decantation is proposed for the preconcentration of the Pb(II) and Co(II) ions in the food samples. The nanoadsorbent was first synthesized via an in situ sonochemical oxidative polymerization method in the presence of FeCl3, as the oxidant, and other additives, including sodium dodecylbenzene sulfonate and ZnO nanoparticles (NPs). The use of an inorganic salt in the centrifugation step was influential on the separation of this highly soft nanocomposite. In the next step, the developed approach was statistically compared with the air-agitated magnetic micro solid-phase extraction method based on the same sorbent substrate but conjugated with magnetic NPs to retrieve the highly soft nanocomposite via magnetic forces. Under the optimal conditions, the two procedures provided comparable linear dynamic ranges with the correlation of determinations higher than 0.98. The detection limits obtained were satisfactory (8.0–10 ng mL−1 for the salt-induced dispersive solid-phase extraction and 0.7–1.5 ng mL−1 for magnetic assisted dispersive solid-phase extraction). The calculated enrichment factor values were approximately the same for the two procedures. In addition, the magnetic dispersive solid-phase extraction procedure enjoyed appropriate repeatability. These satisfactory validations satisfy the high efficiency of the salt-induced and magnetic procedures and the effectiveness of the used nanocomposites to establish versatile retention mechanisms without any crucial demand for the derivatization or complexing agents.

Ultrasonication-facilitated synthesis of functionalized graphene oxide for ultrasound-assisted magnetic dispersive solid-phase extraction of amoxicillin, ampicillin, and penicillin G.

Asimplistic approach is presentedfor the synthesis of ultrasonically fabricated graphene oxide functionalized with polyaniline and N-[3-(Trimethoxysilyl)propyl]ethylenediamine. The synthesized nanocomposite was then employed for the facile, green, ultrasound-assisted, magnetic dispersive solid-phase extraction of amoxicillin, ampicillin, and penicillin G in milk samples and infant formula prior to high-performance liquid chromatography-ultraviolet determination. The designed nanocomposites were comprehensively characterized using field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray powder diffraction, and Fourier transform infrared spectroscopy. In order to achieve the best extraction efficiencies, the influential parameters including pH, amount of magnetic sorbent, type and volume of elution solvent, extraction time, sample volume, and desorption time were assessed. At the optimum conditions, linear ranges of 2.5-1000 (μgL-1) for ampicillin and penicillin G and alinear range of 2.5-750 (μgL-1) were obtained for amoxicillin at optimum conditions. Moreover, the limits of detection (S/N = 3) of 0.5, 0.8, and 0.9 (μgL-1) were obtainedfor amoxicillin, ampicillin, and penicillin G, respectively. The precision (relative standard deviations (%)) values of 3.1, 2.6, and 2.5 at the concentration of 50μgL-1 for seven replicates were obtained for ampicillin, amoxicillin, and penicillin G, respectively. The efficiencies of ≤ 96% and relative standard deviations of less than 3.1% were also obtained thereby confirming the high potential of thesynthesized nanocomposites for simultaneous preconcentration and separation of the β-lactam antibiotics in complex matrixes. Graphical Abstract.