Magnetic Dispersive Solid-phase Extraction Research Articles

Ultrasensitive Determination of Arsenic in Juvenile Eyeshadow by Novel Dispersive Magnetic Solid-Phase Extraction (MSPE) and Flow Injection Analysis – Hydride Generation Atomic Absorption Spectrometry (FIA-HG-AAS)

A new procedure is reported for arsenic preconcentration in juvenile eyeshadow using maghemite nanoparticles (γ-Fe2O3) and determination by flow injection analysis – hydride generation atomic absorption spectrometry (FIA-HG-AAS). Maghemite nanoparticles were synthesized and characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and N2 adsorption measurements at −196 °C. The results showed a crystalline size of 9.1 nm and a surface area of 106 m2 g−1. The experimental conditions for the hydride generation system and the preconcentration process were optimized using a central composite design. For hydride generation, the levels of the concentration of the factors HCl, NaBH4, and flow of carrier gas were optimized, with optimal conditions of 4 mol L−1, 1.1% (m/v), and 145 mL min−1, respectively. The optimized conditions obtained for the adsorption process were a pH equal to 5.3, a mass of γ-Fe2O3 of 184 mg, and stirring time of 41 min in the presence of the sample matrix. The enrichment factor was 50, and the limit of detection was 0.9 μg g−1. Recovery values ranged from 75 to 99%.

Sonochemical synthesis of deep eutectic solvent-coated magnetic nanoparticles and their application in magnetic dispersive micro solid phase extraction–dispersive liquid–liquid microextraction of polycyclic aromatic hydrocarbons from mascara

In this study, application of magnetic dispersive micro solid phase extraction of polycyclic aromatic hydrocarbons from mascara was reported. The extracted analytes were concentrated by a dispersive liquid–liquid microextraction procedure to reach high enrichment factors and low detection limits. In this work, deep eutectic solvent-coated iron nanoparticles were synthesized sonochemically and characterized by energy–dispersive X–ray spectroscopy, scanning electron microscopy, Furrier transform infrared spectrometry, and vibrating sample magnetometry. The extraction procedure was done by extracting the analytes from mascara into an aqueous solution composed of methanol and deionized water. Then the sorbent was added into the solution and the mixture was vortexed. After that the sorbent was separated from the aqueous solution and the analytes were desorbed by methanol with the aid of vortexing. Whole of the elution solvent was collected and mixed with carbon tetrachloride and dispersed into sodium chloride solution. Validation data showed that limits of detection and quantification were within the ranges of 0.33–0.57 and 1.1–1.9 ng/g, respectively. Relative standard deviation values were ≤ 8.6%. The extraction recovery values were in the range of 80–95%. The new method was successfully used for the analysis of the studied compounds in five mascara samples and three analytes were detected in all samples at ng/g level.

Progress in preparation of plant biomass-derived biochar and application in pesticide residues field

随着农药的广泛使用,其已普遍存在于环境中,对人们的身体健康产生巨大影响。因此,环境中农药残留的去除和分析检测对保护人体安全健康至关重要。同时,农药在环境中残留浓度低,需要一种对目标物有较强选择性和富集作用,并对环境影响小的前处理吸附剂。植物源生物炭是由植物源生物质作为碳源衍生得到的材料,其比表面积大、孔容量高、表面官能团可调节,且环境相容性好,其原料植物源生物质的价格低廉、来源广泛并可再生,是一种廉价高效的吸附剂。该文主要综述了近10年来植物源生物炭用于环境中农药残留去除和分析检测前处理的应用进展。其中在农药残留去除方面的应用主要包括降低农药在土壤中的移动性,修复手性农药造成的污染,负载降解农药的细菌及作为化肥的缓释载体。在农药残留分析检测前处理方面,植物源生物炭可用作分散固相萃取、固相微萃取和磁性固相萃取的吸附剂来选择性吸附水果和蔬菜中的有机磷类和三唑类农药,以及水环境中的有机氯类农药。另外,还介绍了植物源生物炭的吸附机理,详细阐述了基于计算模拟如密度泛函理论、分子动力学模拟和巨正则蒙特卡洛模拟的吸附机理研究并讨论了其优势。最后,总结了植物源生物炭在农药去除和农药残留分析检测前处理方面应用的优势,指出了其在农药残留领域应用待解决的问题。

Facile Preparation of Magnetic Graphene Oxide and its Application in Magnetic Dispersive Solid-Phase Extraction of Insecticides from Vegetable Samples

Facile Preparation of Magnetic Graphene Oxide and its Application in Magnetic Dispersive Solid-Phase Extraction of Insecticides from Vegetable Samples

Preparation of a magnetic sorbent based on Tanacetum extract and its application in the extraction of Cu(II) and Pb(II) ions from milk performed in a narrow-bore tube followed by dispersive liquid–liquid microextraction

In this work, an efficient magnetic sorbent has been prepared using the extract of Tanacetum leaves and used in magnetic dispersive solid phase extraction of Cu(II) and Pb(II) ions from high volume of milk samples performed in a narrow-bore tube. For this purpose, first, the sorbent was prepared by mixing Fe3O4 magnetic nanoparticles and Tanacetum leaves extract. After precipitation of the milk proteins with trichloroacetic acid, the sedimented compounds were removed and the upper solution was filled into the narrow-bore tube. Then after that, the mg-level of the prepared sorbent was added. After doing the extraction procedure, the sorbent particles were removed from the tube in the presence of a magnetic field. The adsorbed analytes were desorbed by methanol and to achieve low detection limits, the eluent obtained from the first step was subjected to dispersive liquid-liquid microextraction. Finally, the enriched analytes were monitored by flame atomic absorption spectrometry. The important parameters affecting the method efficiency such as the sorbent amount, type and volume of elution and extraction solvents, vortex time, pH, and ionic strength were studied. Under optimized conditions, the proposed method showed linear ranges of 0.50–40 and 0.75–40 µg L−1 for Cu(II) and Pb(II) ions, respectively. Limits of detection were obtained 0.16 and 0.22 µg L−1 for Cu(II) and Pb(II), respectively. Enrichment factors of 182.5 and 173.7 and extraction recoveries of 95.8 % and 91.2 % were obtained for Cu(II) and Pb(II), respectively. The relative standard deviations (intra- and inter-day precisions) for 5 and 25 µg L−1 of each cation were between 2.4 % and 4.3 %.

Three-dimensional acanthosphere-like hierarchical Co@graphitic carbon for dispersive magnetic solid-phase extraction of nitroimidazole

Herein, a magnetic three-dimensional acanthosphere-like hierarchical Co@graphitic carbon (3D Co@GC) is introduced as an efficient adsorbent for extraction of three nitroimidazoles (NMZs: metronidazole (MNZ), ornidazole (ONZ) and tinidazole (TNZ)) from environmental water and food samples. The proposed 3D Co@GC was synthesized by a simple template-free method, which consisted of plentiful freely arranged one-dimensional nanowires. The adsorption properties of 3D Co@GC for three NMZs were investigated systematically by adsorption kinetic and isotherm studies. 3D Co@GC exhibits good adsorption capacity and fast adsorption kinetics toward three NMZs by virtue of its unique hierarchical structure. In addition, it was also found that a bit of methanol can effectively elute the adsorbed NMZs, eliminating the need for other dangerous strong acid or base solutions. Thus, 3D Co@GC as adsorbent to extraction three trace NMZs followed by direct quantification detection of targets with high-performance liquid chromatography with ultraviolet–visible detector (HPLC-UV) was developed. The parameters of dispersed magnetic solid-phase extraction (d-MSPE) were optimized by univariate and multivariate methods (Box-Behnken design). This established method revealed wide linear range and low limits of detection. Furthermore, the satisfactory recoveries of NMZs (86.7–106.7%) were acquired in spiked river water, honey, milk, and muscle samples. This study might provide a potential strategy for the efficient extraction and sensitive analysis of trace NMZs in river water, honey, milk, and muscle samples.

Tailored-designed material for the preconcentration of Cd(II) on glycidyl methacrylate-based ion-imprinted polymer for flame atomic absorption for trace determination in real samples: multivariate optimization.

A new Cd(II)-imprinting polymer was synthesised based on glycidyl methacrylate (Fe3O4@GMA@IIP) and employed to develop a dispersive magnetic solid-phase extraction method for the preconcentration prior to the determination of Cd(II) from the environmental samples. A central composite design (CCD) based on response surface methodology was used for optimization of the process variables and the material shows the promising saturation adsorption capacity of 28.21mgg-1 under the optimum pH of 4.9 within 15.2min at saturation concentration 914μgmL-1. The experimental data were well described by Sips isotherm model and Brouers-Sotolongo fractal kinetic model that indicated the surface heterogeneity and involvement of both chemisorption and physisorption process. Thermodynamic results documented the endothermic and spontaneous nature of adsorption. The sorbent manifest the economic feasibility maintaining its sorption efficiency after the regeneration by 1M HNO3 and reusability up to 6 adsorption/desorption cycles. The developed method exhibited the preconcentration factor of 30 and a high degree of tolerance for matrix ions. Limit of detection (LOD) and quantification (LOQ) were calculated as 3.054 and 10.182μg L-1 respectively. The developed method was validated by the standard reference material and spiking addition method in real samples, and obtained results showed good agreement in accordance with spiking values. The ease of magnetic separation, high selectivity, good adsorption capacity and faster kinetics made this material a promising candidate for Cd(II) determination in various food and aqueous samples.

Application of magnetic iron (III) oxinate nanocomposite as an efficient sorbent in magnetic dispersive solid phase extraction of pesticides

In this study, a magnetic iron (III) oxinate nanocomposite with high adsorption capacity and saturation magnetization was synthesized through coprecipitation in a short time and used as a sorbent in magnetic dispersive solid phase extraction of some pesticides from fruit juice and fruit samples. This step was followed by a dispersive liquid–liquid microextraction method to more enrichment of the analytes before their quantification by gas chromatography equipped with a flame ionization detector. To verify the successful synthesis of the sorbent, it was characterized using techniques including X–ray diffraction, Fourier transform infrared spectrophotometery, scanning electron microscopy, energy–dispersive X–ray spectroscopy, and vibrating sample magnetometry. According to the method validation experiments, the proposed method provided low limits of detection (0.23–0.57 µg L−1) and quantification (0.79–1.74 µg L−1). The repeatability of the suggested approach, expressed as relative standard deviations, were equal to or less than 7.11% (at the concentrations of 25 and 50 µg L−1 of each analyte). The enrichment factors and extraction recoveries for the pesticides ranged from 217 to 449 and 43.1–89.1%, respectively. Finally, the efficiency of the proposed extraction procedure was verified by its applying on various fruit juice and fruit samples.

Magnetic dispersive solid-phase extraction of some polycyclic aromatic hydrocarbons from honey samples using iron (III) oxinate nanocomposite as an efficient sorbent.

In this work, iron (III) oxinate magnetic nanocomposite was synthesized and employed as an efficient sorbent for the magnetic dispersive solid-phase extraction of some polycyclic aromatic hydrocarbons from honey samples. In the following, dispersive liquid-liquid microextraction procedure was used for further preconcentration of the analytes. The prepared sorbent was characterized using Fourier transform infrared spectrophotometry, X-ray diffractometry, vibrating sample magnetometry, energy dispersive X-ray spectroscopy, and scanning electron microscopy. The results verified the successful formation of the magnetic sorbent. In the extraction process, the sorbent was added into an aqueous solution and the mixture was vortexed. After completing the adsorption process, the supernatant phase was separated in the presence of a magnet and the analytes adsorbed onto sorbent were eluted by acetonitrile. Then, microliter-level 1,1,1-trichloroethane was mixed with the obtained acetonitrile and injected into NaCl solution. Finally, one microliter of the sedimented phase was injected into gas chromatography-flame ionization detector after centrifugation. Under the optimum conditions, a great repeatability (relative standard deviation equal or less than 5 and 6% for intra- and interday precisions, respectively), acceptable extraction recoveries (59-84%), high enrichment factors (118-168), and low limits of detection and quantification (0.16-0.36 and 0.56-1.22 ng/g, respectively) were acquired.

Determination of Ultratrace Levels of Cobalt (II) and Chromium (III) by Magnetic Dispersive Solid-Phase Extraction (SPE) Using Urea-Formaldehyde Polymer/Magnetite Nanoparticles with Flame Atomic Absorption Spectrometry (FAAS)

A fast, selective and sensitive magnetic dispersive solid-phase extraction (SPE) method is presented for the first time for simultaneous preconcentration of ultra-trace levels of cobalt (II) and chromium (III) before their quantification by flame atomic absorption spectrometry (FAAS). Urea-formaldehyde polymer/magnetite nanoparticles (UFP/MNPs) were used as adsorbents. The prepared nano-adsorbent was assessed by x-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM). The excellent magnetic properties of the prepared adsorbent promote rapid isolation of the analytes. A comprehensive study was performed on the extraction conditions and optimal levels of effective parameters were determined. Using the optimum conditions, linear dynamic ranges of 0.8–150 and 0.3-80 μg L−1 were obtained for cobalt (II) and chromium (III), respectively. The limits of detection were 0.2 and 0.09 µg L−1 for cobalt (II) and chromium (III). Intra-day and inter-day relative standard deviations (RSDs) were 3.8% and 5.7%, respectively. Adsorption isotherms were investigated and high adsorption capacities were obtained for the metal ions. The developed method managed to extract and quantify the analytes from unspiked and spiked environmental water samples from the Caspian Sea, Ardabil Balighli Chay River, and Ardabil tap water. The recoveries and relative standard deviations for the samples were from 98.2 to 103% and 0.2 to 5.7%, respectively. The results were validated by comparison with inductively coupled plasma – optical emission spectroscopy (ICP-OES) measurements.

Highly efficient dispersive liquid-liquid microextraction assisted by magnetic porous carbon composite-based dispersive micro solid-phase extraction for determination of tramadol and methadone in urine samples by gas chromatography-mass spectrometry

The recognition of opioids, either as prescription drugs or illicit narcotics, is one of the hot challenges in the analytical field, especially in forensic medicine. Here, a rapid and high efficient air-assisted dispersive liquid-liquid microextraction (DLLME) running after a dispersive magnetic solid-phase extraction (MSPE) is developed for simultaneous extraction and preconcentration of tramadol and methadone in urine samples prior to gas chromatography-mass spectrometry (GC–MS) determination technique. The samples were first mixed with a new magnetic and porous adsorbent, based on a metal-organic framework (MOF) derived NH2-functionalized Fe3O4 nanoparticles-carbon nanocomposite (NH2-Fe3O4@C). Then, the eluent, containing the retrieve analytes, was directly applied as the disperser solvent, along with dichloromethane extracting solvents, to perform DLLME. The combination of MSPE, using the new high surface area sorbent, with a high-performance DLLME resulted in exceptional enrichment factors and extraction recoveries. Under the optimized conditions, linear ranges of 0.1–30 ng mL−1 and 0.1–35 ng mL−1, and detection limits of 73 and 32 pg mL−1, were obtained for tramadol and methadone, respectively. The developed system was utilized for the extraction and preconcentration of tramadol and methadone in some urine samples of suspected drug users, with a reasonable reproducibility (2.4–4.5%). The results were in good agreement with those of the official HPLC/MS-MS technique.

One-pot synthesis of nickel oxide/nickel ferrite nanocomposite and application to dispersive magnetic solid-phase extraction of zinc(II) ions in water and milk samples

An inorganic magnetic nanocomposite named nickel oxide/nickel ferrite (NiO/NiFe2O4) was synthesized using a one-pot hydrothermal method. After successful synthesis and characterization of the nanocomposite, it was applied as a novel adsorbent for dispersive magnetic solid-phase extraction and pre-concentration of zinc(II) ions followed by flame atomic absorption spectrometric detection. The developed method was validated by exploring the affecting parameters, including the amount of the adsorbent (100 mg), sample volume (150.0 mL), sample pH (6.0), adsorption time (15 min), type and eluent concentration (acetic acid 2.0 M), and desorption time (15 min). In the optimal condition, the calibration graph is linear in the concentration range of 0.3–20.0 ng mL1 with a satisfactory determination coefficient of 0.9996. The limit of detection and limit of quantification of the method are 0.04 and 0.13 ng mL1, respectively. The precision of the method in the term of intra-day and inter-day relative standard deviation with six replicates are 1.5% and 3.5%, respectively. A certified reference sample was analyzed applying the developed method and the results confirmed its high accuracy. The applicability of the method was also assayed by determination of Zn(II) ions in various water and milk samples, and the acceptable relative recovery values (96.0–102.0%) were obtained for the spiked samples.

Preparation of magnetic nanoparticle-cholesterol imprinted polymer using semi-covalent imprinting approach for ultra-effective and highly selective cholesterol adsorption

In the present study, a magnetic nanoparticle-cholesterol imprinted polymer for cholesterol (CHO) adsorption exploring semi-covalent imprinting approach was proposed. The Fe3O4/SiO2/MIP synthesis was carried out by using surface imprinting polymerization technique on the silica-coated magnetite, using 3-(triethoxysilyl)propyl isocyanate (ICPTES) as functional monomer and CHO as template, where occurs a covalent bond between them, and TEOS as a cross-linking reagent. The Fe3O4/SiO2/MIP material was characterized by X-ray diffractometry (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), X-ray fluorescence (XRF), values of specific surface area, pore size, and pore volume through nitrogen adsorption/desorption isotherms and vibrating sample magnetometry (VSM). The surface area of Fe3O4/SiO2/MIP (151.04 m2 g−1) was significantly higher compared to Fe3O4/SiO2/NIP (66.09 m2 g−1) and based on relative selectivity coefficient (k´), Fe3O4/SiO2/MIP showed higher selectivity towards CHO in competitive adsorption studies CHO/5-α-cholestane, CHO/7-dehydrocholesterol and CHO/estradiol in chloroform. From the kinetic study, the adsorption equilibrium for Fe3O4/SiO2/MIP was quickly achieved at 60 s in a vortex mixer and described by the second-order kinetic model. High adsorption capacity for Fe3O4/SiO2/MIP (314.1 mg g−1) was obtained from the isotherm studies, and it was adjusted to dual-site Langmuir–Freundlich isotherm model. The obtained outcomes in terms of selectivity, maximum adsorption capacity, and fast kinetic make the magnetic nanoparticle-cholesterol imprinted polymer an outstanding material for future application in magnetic dispersive solid-phase extraction for analytical purposes.

Simultaneous determination of lead and copper in Polygonatum kingianum by ICP OES combined with natural deep eutectic solvent-based magnetic dispersive micro solid phase extraction

The work effectively combined natural deep eutectic solvent-based magnetic dispersive micro solid phase extraction with ICP OES and established a method for the simultaneous determination of Pb and Cu in natural medicine Polygonatum kingianum.

Surfactant assisted magnetic dispersive micro solid phase extraction-HPLC as a straightforward and green procedure for preconcentrating and determining Caffeine, Lidocaine, and Chlorpromazine in biological and water samples

ABSTRACT Magnetic dispersive micro solid-phase extraction as a proper and selective sample preparation was developed to extract and clean up three drugs, including Caffeine (CAF), Lidocaine (LID), and Chlorpromazine (CPZ), before determining by HPLC-DAD. Nickel-doped BiFeO3 was synthesised using the sol–gel method as a magnetic sorbent core and coated with tetraethyl orthosilicate (TEOS) to enhance the sorbent stability and the sorbent selectivity. In the extraction procedure, the sorbent was dispersed into acetonitrile as disperser solvent and sodium dodecyl sulphate (SDS) as a disperser agent before injecting into the sample solution to extract the analytes. Several influential factors in the method were evaluated using an experimental design strategy. Under the optimum conditions, the method displayed wide linearity in the concentration ranges of 20.8–365, 1.4–389, and 2.7–355 ng mL−1 to determine CAF, LID, and CPZ with a suitable R2 between 0.9963 and 0.9971, respectively. Intra-day and inter-day relative standard deviations were in the ranges of 3.5–3.8 and 3.9–4.3%. LODs and LOQs for the determination of CAF, LID, and CPZ were lower than 6.3 and 20.8 ng mL−1. The method is convenient for determining the analytes in real water and biological samples with RSD (n = 3) and recovery in the ranges of 3.0–4.3% and 87.5–96.9%, respectively.

Theoretical Design and Preparation of Ionic Liquid-Based Magnetic Nanoparticles for the Magnetic Dispersive Solid-Phase Extraction of Benzimidazoles in Human Plasma

Theoretical Design and Preparation of Ionic Liquid-Based Magnetic Nanoparticles for the Magnetic Dispersive Solid-Phase Extraction of Benzimidazoles in Human Plasma

Polydopamine-coated magnetic Spirulina nanocomposite for efficient magnetic dispersive solid-phase extraction of aflatoxins in pistachio

An efficient adsorbent was synthesized and used in magnetic dispersive solid phase extraction (MDSPE) of aflatoxins B1, B2, G1, and G2 at trace levels in pistachio prior to analysis by HPLC equipped with a fluorescence detector. Spirulina (Sp) algae was first magnetized, followed by surface modification with dopamine (Dp). The adsorbent was characterized using FT-IR, XRD, FE-SEM, EDX, VSM, and BET analyses. The effects of different analytical parameters on the extraction performance were evaluated. Under optimal conditions, good limits of detection (LODs) and quantifications (LOQs) were achieved in the ranges of 0.02–0.07 and 0.06–0.21 ng g−1, respectively. The RSDs were 5.9, 6.3, 5.6, and 7.3% for AFB1, G1, B2, and G2, respectively. The proposed method was successfully used to determine AFs in pistachio samples and acceptable recoveries in the range of 72–95% were obtained.

Magnetic dispersive solid phase extraction based on carbonized cellulose–ferromagnetic nanocomposite for screening phthalate esters in aqueous samples

In this work, a sorbent of the carbonized cellulose–ferromagnetic nanocomposite has been proposed for the magnetic dispersive solid phase extraction of some plasticizers in aqueous samples. Carbonized cellulose nanoparticles were prepared by treatment of cellulose filter paper with concentrated sulfuric acid and then loaded on Fe3O4 nanoparticles using coprecipitation. This sorbent is compatible with aqueous samples and can be considered as a viable sorbent for extraction of plasticizers from aqueous samples. In this study, magnetic dispersive solid phase extraction is followed by a dispersive liquid–liquid microextraction method. This combination makes the proposed approach as an efficient clean–up method with high enrichment factors for the selected analytes. The enriched analytes are monitored by gas chromatography equipped with a flame ionization detector. Parameters affecting the method efficiency were investigated in details. Under the optimized extraction conditions, limits of detection could reach up to of 0.15–0.50 µg L−1. The satisfactory enrichment factors of 286–403 were obtained, and the extraction recoveries were found to be in the range of 57–80%. Relative standard deviations were in the range of 3–7% for intra–day and inter–day precisions for six replicate extractions at 25 µg L−1 of each plasticizer. Calibration curves were linear in wide ranges with coefficients of determination ≥ 0.995. Eventually, efficiency of the prepared sorbent was confirmed by the extraction of some plasticizers from real samples including fruit juices, mineral water, injection solution, cola, and yoghourt drink packed in plastic containers.

HILIC-MS/MS for the Determination of Methylated Adenine Nucleosides in Human Urine.

N6-methyl-2'-deoxyadenosine (m6dA) is a newly discovered DNA epigenetic mark in mammals. N6-methyladenosine (m6A), 2'-O-methyladenosine (Am), N6,2'-O-dimethyladenosine (m6Am), and N6,N6-dimethyladenosine (m62A) are common RNA modifications. Previous studies illustrated the associations between the aberrations of these methylated adenosines in nucleic acids and cancer. Herein, we developed Fe3O4/graphene-based magnetic dispersive solid-phase extraction for the enrichment and hydrophilic interaction liquid chromatography-mass spectrometry (HILIC-MS/MS) for the measurements of m6dA, m6A, Am, m6Am, and m62A in human urine samples. We found that malic acid could improve the HILIC-based separation of these modified nucleosides and markedly enhance the sensitivity of their MS detection. With this method, we accurately quantified the contents of these modified adenine nucleosides in urine samples collected from gastric and colorectal cancer patients as well as healthy controls. We found that, relative to healthy controls, urinary m6dA and Am levels are significantly lower for gastric and colorectal cancer patients; while gastric cancer patients also exhibited lower levels of urinary m6A, the trend was opposite for colorectal cancer patients. Together, we developed a robust analytical method for simultaneous measurements of five methylated adenine nucleosides in human urine, and our results revealed an association between the levels of urinary methylated adenine nucleosides and the occurrence of gastric as well as colorectal cancers, suggesting the potential applications of these modified nucleosides as biomarkers for the early detection of these cancers.

Magnetic Amino-Modified Multiwalled Carbon Nanotube (MWCNT) Based Magnetic Dispersive Solid-Phase Extraction (m-dSPE) for the Determination of Paralytic Shellfish Toxins in Bivalve Mollusks with Hydrophilic Interaction Liquid Chromatography–Tandem Mass Spectrometry (HILIC-MS/MS)

A sensitive and efficient magnetic amino modified multi-walled carbon nanotubes (m-MWCNT-NH2)-based magnetic dispersive solid-phase extraction (m-dSPE) coupled with hydrophilic interaction liquid chromatography–tandem mass spectrometry (HILIC-MS/MS) strategy is reported for the simultaneous determination of 13 paralytic shellfish toxins (PSTs) in bivalve mollusks. The samples were extracted twice with 1% acetic acid and purified using optimized m-dSPE procedures with Fe3O4 coated MWCNT-NH2 composites as magnetic adsorbents. The adsorbed PSTs on the m-MWCNT-NH2 adsorbents were separated using a Ni-coated neodymium magnet and subsequently eluted with 2 mL water–acetonitrile–acetic acid (80:20:1, v/v/v) and analyzed by HILIC-MS/MS. The correlation coefficients (r) of the targeted toxins obtained in matrix-matched external standard curves were from 0.997 to 0.999. The PSTs were acquired and quantified in the multiple reaction-monitoring mode and the limits of detection and quantitation in bivalve mollusks were 1.10 to 4.51 μg/kg and 3.67 to 13.5 μg/kg, respectively. Spiked recoveries at three concentrations in negative samples were from 73.4% to 92.5% with precision less than 10.6%. The method validation was in accordance with 2002/657/EC guidelines and method application in commercial bivalve mollusk samples. The developed method was rapid, convenient and economical for the determination of the targeted toxins.