Magnetic nanocomposite of self‐doped polyaniline–graphene as a novel sorbent for solid‐phase extraction

This work is the first study on the extraction efficiency of self‐doped polyaniline that is immobilized on the graphene‐modified magnetic nanoparticles. The new material was used as a sorbent for the magnetic solid‐phase extraction of methyl‐, propyl‐, and butylparabens. The use of graphene provides a high surface area and prevents aggregation of the nanoparticles. The self‐doped polyaniline also provides multifunctionality, high extraction capacity, and chemical stability even in the basic medium. The parabens were acetylated for determination by gas chromatography with flame ionization detection. The effects of monomer ratio, extraction solvent, sorbent amount, sample volume, desorption solvent volume, adsorption and desorption times, and sample ionic strength were optimized. Preconcentration factors obtained were from 190 to 310. The detection limits of the method were <2.8 μg/L. Linear ranges of the method were 5–2000 μg/L for propyl and butyl parabens, and 10–2000 μg/L for methyl paraben. The method was applied for the determination of the parabens in cosmetic products and extraction recoveries were 89–101% with RSDs ≤7.9%.     

Development of a new strategy for the synthesis of graphene oxide-alumina nanocomposite as an efficient adsorbent for dispersive solid-phase extraction of parabens

The present study investigates the synthesis and application of the graphene oxide-alumina nanocomposite as a new adsorbent for the dispersive solid-phase extraction of three parabens and their determination using high-performance liquid chromatography-ultraviolet detection. The characterization of the synthesized material was accomplished and its size, morphology, chemical composition, porosity, and thermal stability were studied. Application of the proposed strategy for the synthesis of the nanocomposite resulted in the incorporation of Al₂O₃ nanoparticles into graphene oxide nanosheets, further resulting in the exfoliation of graphene oxide nanosheets increasing their surface area. An orthogonal rotatable central composite design was used to optimize the extraction. Under the optimum conditions, the analytical performance of the method showed a suitable linear dynamic range (0.2–100.0 μg/L), reasonable limits of detection (0.03–0.05 μg/L), and preconcentration factors ranging from 128 to 173. Finally, the new validated method was applied for the determination of parabens in some real samples including wastewater, cream, toothpaste, and juice samples with satisfactory recoveries (88%–109%), and relative standard deviations less than 8.7% (n = 3). Results demonstrated that inserting alumina nanoparticles into graphene oxide nanosheets improved the extraction efficiency of parabens, as polar acidic compounds, by providing additional efficient interactions including hydrogen bonding, dipole-dipole, and Brønsted and Lewis acid-base interactions.     

Porous‐membrane‐protected polyaniline‐coated SBA‐15 nanocomposite micro‐solid‐phase extraction followed by high‐performance liquid chromatography for the determination of parabens in cosmetic products and wastewater

A SBA‐15/polyaniline para‐toluenesulfonic acid nanocomposite supported micro‐solid‐phase extraction procedure has been developed for the extraction of parabens (methylparaben, ethylparaben, and propylparaben) from wastewater and cosmetic products. The variables of interest in the extraction process were pH of sample, sample and eluent volumes, sorbent amount, salting‐out effect, extraction and desorption time, and stirring rate. A Plackett–Burman design was performed for the screening of variables in order to determine the significant variables affecting the extraction efficiency. Then, the significant factors were optimized by using a central composite design. The optimum experimental conditions found at 50 mL sample solution, extraction and desorption times of 40 and 20 min, respectively, 500 μL of 3% v/v acetic acid in methanol as eluent, 0.01 M salt addition, and 10 mg of the sorbent. Under the optimum conditions, the developed method provided detection limits in the range of 0.08–0.4 ng/mL with good repeatability (RSD% < 7) and linearity (r² = 0.997–0.999) for the three parabens. Finally, this fast and efficient method was employed for the determination of target analytes in cosmetic products and wastewater, and satisfactory results were obtained.     

共价有机框架材料磁固相萃取-高效液相色谱法分析环境水体中对羟基苯甲酸酯

建立了一种基于共价有机框架材料的磁固相萃取-高效液相色谱方法,用于环境水样中对羟基苯甲酸酯的快速灵敏分析。首先以Fe₃O₄纳米粒子为磁核,通过1,3,5-苯三甲醛(Tb)和联苯胺(Bd)在室温下的席夫碱反应合成了磁性共价有机框架材料——Fe₃O₄@TbBd,通过扫描电镜、热重分析、X射线衍射和振动样品磁强计等表征手段证明了该磁性共价有机框架材料具有良好的热稳定性和化学稳定性,且磁响应强度较大,是用于磁固相萃取的理想材料。随后系统研究了影响萃取效率的因素,包括吸附剂用量、萃取时间、pH、解吸溶剂、解吸时间和解吸次数,建立了基于Fe₃O₄@TbBd的磁固相萃取-高效液相色谱测定环境水样中4种对羟基苯甲酸酯的方法。方法的线性范围良好,4种目标物的检出限和定量限范围分别为0.2~0.4 μg/L和0.7~1.4 μg/L,加标回收率为86.1%~110.8%,日内和日间精密度的相对标准偏差(RSD)分别低于5.5%和4.9%。最后将该方法应用于东湖水、长江水和生活废水中对羟基苯甲酸酯的测定,不同加标水平下对羟基苯甲酸酯的回收率在80.7%~117.5%之间,RSD在0.2%~8.8%之间。该方法操作简单,萃取时间短,灵敏度较高且对环境友好,在环境水样中对羟基苯甲酸酯的检测方面有良好的应用潜力。     

Solvent‐assisted dispersive micro‐SPE by using aminopropyl‐functionalized magnetite nanoparticle followed by GC‐PID for quantification of parabens in aqueous matrices

In this research, solvent‐assisted dispersive micro‐SPE was introduced as a simple modified technique for the determination of parabens in water and cosmetic samples. Aminopropyl‐functionalized magnetite nanoparticles (MNPs) were successfully synthesized and applied. GC with photoionization detector was used for the separation and detection of parabens. In this method, hexylacetate (15 μL) as a solvent and aminopropyl‐functionalized MNPs (5 μg) as a sorbent were added to an aqueous sample (10 mL) and then the sample was sonicated. Dispersed magnetite was collected in the bottom of the conical tube by using a strong magnet and then ACN was added as a desorption solvent. Forty microliters of this solvent was transferred into a microvial and then acetic anhydride and pyridine were added, thus derivatization was performed by acetic anhydride. After evaporation, 1 μL of derivatized sample was injected into a gas chromatograph for analysis. Several important parameters, such as kind of organic solvent, desorption solvent and volume, amount of aminopropyl‐functionalized MNPs and effect of salt addition were investigated. Under optimum conditions, the limits of detection achieved were between 50 and 300 ng/L, with RSDs (n = 5) lower than 8%. Under the optimum conditions, the enrichment factors ranged from 217 to 1253 and the extraction recoveries ranged from 10 to 62%. The recoveries were obtained for the analytes in river water and mouthwash solution and hand cream in the range of 87–103%. The advantages of proposed method are simplicity of operation, rapidity, high extraction yields, and environmental friendly character.     

Polyaniline-coated magnetite nanoparticles incorporated in alginate beads for the extraction and enrichment of polycyclic aromatic hydrocarbons in water samples

A magnetic solid-phase extraction sorbent consisting of polyaniline-coated magnetite nanoparticles entrapped in alginate beads (PANI/alginate/Fe₃O₄) was successfully synthesised and applied for the extraction and preconcentration of polycyclic aromatic hydrocarbons (PAHs) in water samples. The magnetite nanoparticles helped to provide an easy and rapid isolation of the sorbent from the sample solution using an external magnet. The alginate beads helped to increase the surface area for polyaniline coating. The polyaniline-coated alginate/magnetite composite helped to increase the extraction efficiency due to the π–π interactions between the polyaniline and the PAHs. Various parameters that affected the extraction efficiencies were optimised including the polymerisation time, the amount of sorbent, sample pH, extraction time, ionic strength, and desorption conditions. Under the optimal conditions, a linear response was achieved in the concentration range of 0.040–50.0 µg L^?1, and the limit of detection was 0.010 µg L^?1. This simple, convenient, cost-effective, and environmentally friendly method was successfully applied for the extraction and enrichment of PAHs in water samples. The recoveries ranged from 86.0% to 97.8% with a relative standard deviation <10 %.     

导电聚苯胺与Fe3O4磁性纳米颗粒复合物的合成与表征

对十二烷基苯磺酸(DBSA)掺杂的导电聚苯胺(PAn-DBSA)的氯仿溶液,在pH为中性的条件下,采用“修饰-再掺杂(Modification-re-doped)法”合成了含有Fe₃O₄磁性纳米颗粒的导电聚苯胺复合物的有机溶液.用FTIR,XRD,TEM,UV-Vis和SQUID等对所得复合物进行了表征,结果表明,该复合物呈现超顺磁性和半导体的导电性,并具有较好的透明性.     

苯并噻唑和铁氧化物纳米粒子修饰的磁性棒碳糊电极上肼的电催化氧化反应：同时检测肼和苯酚

开发了一种磁性Fe3O4纳米粒子和2-(3,4-二羟苯基)苯并噻唑(DPB)修饰的磁性棒碳糊电极(MBCPE)用于电化学检测肼.首先将DPB自组装在Fe3O4纳米粒子上,然后将此复合物吸附于设计的MBCPE上. MBCPE电极将磁性纳米粒子吸引到电极表面.所得新型电极具有高的导电性和大的有效比表面积,因而对肼的电催化氧化反应有非常大的电流响应.采用伏安法、扫描电镜、电化学阻抗谱、红外光谱和紫外-可见光谱对修饰电极进行了表征.采用伏安法研究了在磷酸盐缓冲溶液(pH=7.0)中MBCPE/Fe3O4NPs/DPB电极上肼的电化学行为.作为电化学传感器, MBCPE/Fe3O4NPs/DPB电极对肼氧化反应表现出极高的电催化活性.在DPB存在下,肼的氧化电势下降,但其催化电流增加.电催化电流与肼浓度在0.1–0.4和0.7–12.0μmol/L二个区间内表现出线性关系,检测限为18.0 nmol/L.另外,研究了MBCPE/Fe3O4NPs/DPB电极同时检测肼和苯酚的性能.伏安实验结果显示,苯酚的线性区域为100–470μmol/L,检测限为24.3μmol/L.采用此电极检测了水样品中的肼和苯酚.     

尺寸可控的聚苯胺复合微球的电纺制备与表征

以十二烷基苯磺酸(DBSA)掺杂的导电聚苯胺与聚乙二醇(PEG)及Fe3O4的混合氯仿溶液,采用静电纺丝(spinning technology)方法制备含Fe3O4纳米颗粒的导电聚苯胺(PANI)/PEG/Fe3O4复合微球.SEM结果表明,电纺所得的PANI/PEG/Fe3O4复合微球结构依赖于PEG聚合物浓度、静...     

Synthesis and characterization of multifunctional Fe3O4/poly(fluorescein O-methacrylate) core/shell nanoparticles

Multifunctional fluorescent and superparamagnetic Fe(3)O(4)/poly(fluorescein O-methacrylate) [Fe(3)O(4)/poly(FMA)] nanoparticles with core/shell structure were synthesized via surface-initiated polymerization. First, polymerizable double bonds were introduced onto the surface of Fe(3)O(4) nanoparticles via ligand exchange and a condensation reaction. A fluorescent monomer, FMA, was then polymerized to the double bonds at the surface via free-radical polymerization, leading to form a fluorescent polymer shell around the superparamagnetic Fe(3)O(4) core. The resultant Fe(3)O(4)/poly(FMA) nanoparticles were characterized by Fourier transform infrared, nuclear magnetic resonance, and X-ray diffraction spectroscopy to confirm the reactions. Transmission electron microscopy images showed that the Fe(3)O(4)/poly(FMA) nanoparticles have a spherical and monodisperse core/shell morphology. Photoluminescence spectroscopy and superconducting quantum interference device magnetometer analyses confirmed that the Fe(3)O(4)/poly(FMA) nanoparticles exhibited fluorescent and superparamagnetic properties, respectively. In addition, we demonstrated the potential bioimaging application of the Fe(3)O(4)/poly(FMA) nanoparticles by visualizing the cellular uptake of the nanoparticles into A549 lung cancer cells.     

Extraction of fluoxetine from aquatic and urine samples using sodium dodecyl sulfate-coated iron oxide magnetic nanoparticles followed by spectrofluorimetric determination

A new method based on the combination of magnetic solid phase extraction (MSPE) and spectrofluorimetric determination was developed for isolation and preconcentration of fluoxetine form aquatic and biological samples using sodium dodecyl sulfate (SDS) coated Fe(3)O(4) nanoparticles (NPs) as a sorbent. The unique properties of Fe(3)O(4) NPs including high surface area and strong magnetism were utilized effectively in the MSPE process. Effect of different parameters influencing the extraction efficiency of fluoxetine including the amount of Fe(3)O(4) and SDS, pH value, sample volume, extraction time, desorption solvent and time were optimized. Under optimized condition, the method was successfully applied to the extraction of fluoxetine from water and urine samples and absolute recovery amount of 85%, detection limit of 20 μg L(-1) and a relative standard deviation (RSD) of 1.4% were obtained. The method linear response was over a range of 50-1000 μg L(-1) with R(2)=0.9968. The relative recovery in different aquatic and urine matrices were investigated and values of 80% to 104% were obtained. The whole procedure showed to be conveniently fast, efficient and economical for extraction of fluoxetine from environmental and biological samples.     

Preconcentration of emerging contaminants in environmental water samples by using silica supported Fe3O4 magnetic nanoparticles for improving mass detection in capillary liquid chromatography

A magnetic material based on Fe(3)O(4) magnetic nanoparticles incorporated in a silica matrix by using a sol-gel procedure has been used to extract and preconcentrate emerging contaminants such as acetylsalicylic acid, acetaminophen, diclofenac and ibuprofen from environmental water samples prior to the analysis with Capillary LC-MS. The use of the proposed silica supported Fe(3)O(4) magnetic nanoparticles enables surfactant free extracts for the analysis with MS detection without interferences in the ionisation step. Under the optimum conditions, we demonstrated the reusability of the magnetic sorbent material during 20 uses without loss in the extraction efficiency. In addition, no cleanup was necessary. The preconcentration factor was 100 and the detection limits were between 50 and 150 ng/L. The proposed procedure has been applied to the analysis of water samples obtaining recoveries between 80 and 110% and RSD values lower than 12%. Concentrations of the target analytes over the range 1.7 and 0.1 μg/L have been found in different water samples.     

利用升华物质2,4,6-三异丙基-1,3,5-三氧杂环己烷作模板剂制备聚苯胺包覆的中空硫电极材料

本文首次提出采用升华物质为模板,制备聚苯胺包覆的中空硫电极材料. 首先通过Na₂S₂O₃和稀HCl反应,在具有升华特性的ADD(2,4,6-三异丙基-1,3,5-三氧杂环己烷)微粒表面沉积一层S,然后在S的表面再沉积聚苯胺包覆层. 在经60 ^oC干燥12小时后,其中的ADD自然挥发,得到聚苯胺壳体包覆的中空硫复合物. SEM、TEM和TG分析表明,制得的聚苯胺包覆中空硫的粒径约为2 μm,硫含量为61.1%. 在500 mA·g^-1充放电电流下,首次放电比容量为776.2 mAh·g^-1,库仑效率为95.9%. 100次充放电循环后,放电比容量为524.7 mAh·g^-1. 由于聚苯胺包覆物的聚苯胺膜具有抑制聚硫锂向外的扩散作用,以及包覆物中的空间对放电时S的膨胀具有缓冲作用,聚苯胺包覆中空硫粉末的放电比容量和充放电稳定性均明显高于未包覆聚苯胺的中空硫和化学制备的硫. 这种制备导电聚合物包覆中空硫的新方法具有操作简单、成本低廉的优点,有进一步发展的前景.     

纳米金与磁性纳米复合物构建电流型免疫传感器的研究

制备了易于磁性分离、硫堇(Thi)包覆的四氧化三铁(Fe3O4)纳米复合物。通过静电吸附作用,将萘酚(Nafion)、Thi包覆的Fe3O4复合纳米粒子层层修饰到玻碳电极表面,再利用Thi分子中的氨基吸附纳米金,最后固载甲胎蛋白抗体,从而制得灵敏度高、稳定性好的无试剂电流型甲胎蛋白免疫传感器。实验通过透射电子显微镜(TEM)对该复合纳米粒子进行表征,并用循环伏安法考察了电极的电化学特性。结果表明,Fe3O4/Thi复合纳米粒子修饰的电极在实验过程中呈现出良好的氧化还原活性,其检测范围为0.05～20μg/L,检出限为0.03μg/L。     

Rapid magnetic solid phase extraction with in situ derivatization of methylmercury in seawater by Fe3O4/polyaniline nanoparticle

A new Fe(3)O(4)/polyaniline nanoparticle (PANI) material has been successfully developed as magnetic solid-phase extraction sorbent in dispersion mode for the determination of methylmercury (MeHg) in aqueous samples, via quantification by gas chromatography/mass spectrometry (GC-MS). The resultant core-shell magnetic solid-phase extraction nanoparticle (MSPE-NP) sorbent was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS) and Fourier transform-infrared (FTIR) spectroscopy. Fe(3)O(4)/PANI composites showed fibrous structure with diameters between 50 and 100 nm for fibers. The MSPE-NP process involved the dispersion of the Fe(3)O(4)/PANI nanoparticles in water samples with sonication, followed by magnetic aided retrieval of the sorbent and then, solvent (hexane) desorption of extracted MeHg for GC-MS analysis. The extraction, derivatization and adsorption conditions were optimized by selecting the appropriate extraction parameters including the amount of sorbent, extraction time, derivatizing reagent volume and extraction solvent. The calibration graph was linear in the concentration range of 0.5-300 ng mL(-1) (R(2)>0.993) with detection limit of 0.1 ng mL(-1) (n=3), while the repeatability was 4.1% (n=5). Enrichment factor was obtained as 91. Seawater sample was analyzed as real sample and good recoveries (>98%) were obtained at different spiked values.     

(Au)核(Ag)壳纳米微粒光度法快速检测过氧化氢

以粒径为10 nm的纳米金为晶种, 用柠檬酸钠还原硝酸银制备了平均粒径为30 nm的(Au)核(Ag)壳纳米微粒, 用高速离心纯化除去过量的柠檬酸三钠获得了较纯的(Au)核(Ag)壳纳米微粒, 其吸收峰位于393 nm处. 在pH 4.4的HAc-NaAc缓冲溶液中, Fenton反应产生的羟基自由基可以氧化(Au)核(Ag)壳纳米微粒银层生成银离子, 导致393 nm处的吸光度降低. H2O2的浓度(c)在6.58～421.1 μmol/L范围内与393 nm处的吸光度降低值ΔA 393 nm呈良好的线性关系, 回归方程为ΔA393 nm=0.00111c+0.0210, 相关系数为0.9908, 检出限为1.73 μmol/L. 本方法用于废水样品测定, 结果满意.     

Preparation of surface plasmon resonance biosensor based on magnetic core/shell Fe3O4/SiO2 and Fe3O4/Ag/SiO2 nanoparticles

In this paper, surface plasmon resonance biosensors based on magnetic core/shell Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles were developed for immunoassay. With Fe(3)O(4) and Fe(3)O(4)/Ag nanoparticles being used as seeding materials, Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles were formed by hydrolysis of tetraethyl orthosilicate. The aldehyde group functionalized magnetic nanoparticles provide organic functionality for bioconjugation. The products were characterized by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), FTIR and UV-vis absorption spectrometry. The magnetic nanoparticles possess the unique superparamagnetism property, exceptional optical properties and good compatibilities, and could be used as immobilization matrix for goat anti-rabbit IgG. The magnetic nanoparticles can be easily immobilized on the surface of SPR biosensor chip by a magnetic pillar. The effects of Fe(3)O(4)/SiO(2) and Fe(3)O(4)/Ag/SiO(2) nanoparticles on the sensitivity of SPR biosensors were also investigated. As a result, the SPR biosensors based on Fe(3)O(4)/SiO(2) nanoparticles and Fe(3)O(4)/Ag/SiO(2) nanoparticles exhibit a response for rabbit IgG in the concentration range of 1.25-20.00 μg ml(-1) and 0.30-20.00 μg ml(-1), respectively.     

Sorption of palladium(II), rhodium(III), and platinum(IV) on Fe(3)O(4) nanoparticles

The adsorption of palladium(II), rhodium(III), and platinum(IV) from diluted hydrochloric acid solutions onto Fe(3)O(4) nanoparticles has been investigated. The parameters studied include the contact time and the concentrations of metals and other solutes such as H(+) and chloride. The equilibrium time was reached in less than 20 min for all metals. The maximum loading capacity of Fe(3)O(4) nanoparticles for Pd(II), Rh(III), and Pt(IV) was determined to be 0.103, 0.149, and 0.068 mmol g(-1), respectively. A sorption mechanism for Pd(II), Rh(III), and Pt(IV) has been proposed and their conditional adsorption equilibrium constants have been determined to be logK=1.72, 1.69, and 1.84, respectively. Different compositions of eluting solution were tested for the recovery of Pt(IV), Pd(II), and Rh(III) from Fe(3)O(4) nanoparticles. It was found that 0.5 mol L(-1) HNO(3) can elute all of the metal ions simultaneously, while 1 mol L(-1) NaHSO(3) was an effective eluting solution for Rh(III), and 0.5 mol L(-1) NaClO(4) for Pt(IV). In competitive adsorption, the nanoparticles showed stronger affinity for Rh(III) than for Pd(II) and Pt(IV).     

无溶剂Fe3O4纳米流体的制备及表征

采用共沉淀法合成Fe3O4纳米粒子, 将含有硅氧烷基的离子型改性剂二甲基十八烷基氯化铵与Fe3O4纳米粒子进行接枝反应, 再用脂肪醇聚氧乙烯醚磺酸盐的长链阴离子交换Cl-, 在Fe3O4纳米粒子表面生成具有阴、 阳离子双电层结构的表面处理层, 得到无溶剂Fe3O4纳米流体. 研究结果表明, 在Fe3O4纳米粒子表面成功接枝了有机物长链, 改性的Fe3O4纳米粒子呈单分散分布, 其损耗剪切模量G″明显大于储能剪切模量G', 具有明显的流体行为, 在室温下即可流动.     

Analysis of Paraben Preservatives in Cosmetic Samples: Comparison of Three Different Dynamic Hollow Fiber Liquid-Phase Microextraction Methods

This study focused on a comparison of three different dynamic hollow fiber-based liquid-phase microextraction (DHF-LPME) methods for extraction and preconcentration of parabens from wastewater, toothpaste, cream, and shampoo samples. The first method is two-phase DHF-LPME, in which n-octanol was used as the extraction solvent. The second is three-phase DHF-LPME, in which n-octanol and basic aqueous solution were used as the extraction solvent and acceptor phase, respectively. High-performance liquid chromatography with UV detection (HPLC–UV) was applied for determination of the parabens in both methods. The third method is a recently introduced method; three-phase DHF-LPME based on two immiscible organic solvents (n-dodecane as organic solvent and acetonitrile as an acceptor phase). The quantitative analyses were performed by the use of gas chromatography-mass spectrometry (GC–MS) after injection port derivatization. The effect of different extraction conditions (i.e., extraction solvent, pH, ionic strength, stirring rate, and dynamic and extraction times) on the extraction efficiency of the parabens was investigated and optimized. All the three procedures provide similar working parameters characterized by high repeatability (3.9–6.3 %) and good linearity (correlation coefficient ranging from 0.989 to 0.998). Results of real sample analyses obtained by these three methods were highly correlated. Although all methods provide compatible alternatives for paraben analysis, the three-phase DHF-LPME based on two immiscible organic solvents may be a more appropriate technique due to its higher extraction efficiency and thus lower limits of detection (LODs). LODs for all the parabens ranged from 0.2 to 5.0 μg L^?1 using the two first methods combined with HPLC–UV. An improvement in sensitivity of several orders of magnitude was achieved using three-phase DHF-LPME based on two immiscible organic solvents followed by single-ion monitoring GC–MS analyses (0.01–0.2 μg L^?1) due to compatibility of this technique with GC instrument.