Preconcentration of copper with multi-walled carbon nanotubes pretreated by potassium permanganate cartridge for solid phase extraction prior to flame atomic absorption spectrometry

A procedure for the preconcentration of copper was described in this paper using multi-walled carbon nanotubes (MWCNTs) oxidized by potassium permanganate as the adsorbent for the enrichment of trace copper in water samples. Important parameters, such as the sample pH, the concentration and volume of eluent, sample flow rate and volume, and interference of coexisting ions, were investigated. The obtained results indicated that proposed method possessed an excellent analytical performance. The linear range, the detection limit, and precison (RSD) were 1–100 ng/mL (R(2) = 0.9993), 0.32 ng/mL and 2.88%, respectively. The results showed that copper could be adsorbed quantitatively on the pretreated MWCNTs with potassium permanganate, and proposed method was very useful in the monitoring of copper in the environment.

Application of multiwalled carbon nanotubes treated by potassium permanganate for determination of trace cadmium prior to flame atomic absorption spectrometry

In this study we investigated the enrichment ability of oxidized multiwalled carbon nanotubes （MWCNTs） and established a new method for the determination of trace cadmium in environment with flame atomic absorption spectrometry. The MWCNTs were oxidized by potassium permanganate under appropriate conditions before use as preconcentration packing. Parameters influencing the recoveries of target analytes were optimized. Under optimal conditions, the target analyte exhibited a good linearity （R^2=0.9992） over the concentration range 0.5-50 ng/ml. The detection limit and precision of the proposed method were 0.15 ng/ml and 2.06%, respectively. The proposed method was applied to the determination of cadmium in real-world environmental samples and the recoveries were in the range of 91.3%-108.0%. All these experimental results indicated that this new procedure could be applied to the determination of trace cadmium in environmental waters.

Preparation, characterization and application of thiosemicarbazide grafted multiwalled carbon nanotubes for solid-phase extraction of Cd(II),Cu(II) and Pb(II) in environmental samples

Thiosemicarbazide-grafted multi-walled carbon nanotubes were prepared and employed to investigate the pre-concentration of Cd（Ⅱ）, Cu（Ⅱ） and Pb（Ⅱ） from aqueous solution prior to their determination by ICP-OES. The resulting material was characterized by FT-IR, TGA and SEM. Various factors influencing the separation and pre-concentration were investigated. The enrichment factor typically is 60. Under optimized experimental conditions, the maximum adsorption capacities of Cd（Ⅱ）, Cu（Ⅱ） and Pb（Ⅱ） were found to be 1.98, 10.94, 3.69 mg/g, and the relative standard deviations are 〈 3.5% （n = 6）. The new adsorbent shows superior reusability and stability. The procedure was successfully applied to the determination of trace quantities of Cd（Ⅱ）, Cu（Ⅱ） and Pb（Ⅱ） in water samples.

Determination of aniline derivatives in water samples after preconcentration with oxidized multiwalled carbon nanotubes as solid-phase extraction disk

A sensitive and selective preconcentration method using solid-phase extraction （SPE） disk made from oxidized multiwalled carbon nanotubes （OMWCNTs）, has been developed for the determination of aniline derivatives, such as 2-nitroaniline （2-NA）, 4- nitroaniline （4-NA）, and 2,4-dichloroaniline （2,4-DCA） in water samples. Anilines were extracted onto OMWCNT disk and then determined by high performance liquid chromatography （HPLC） with UV detector. Several parameters on the recovery of the analytes were investigated. The experimental results showed that it was possible to obtain quantitative analysis when the solution pH was 8 using 200 mL of validation solution containing 2 ug of anilines and 10 mL of acetonitrile/ethanol （8/2, v/v） as an eluent. Relative standard deviations for five determinations were 7.5% （2-NA）, 6.5% （4-NA） and 3.8% （2,4-DCA） under optimum conditions. The linear range of calibration curves were 0.5 ng.mL 1 to 15 ng.mL-1 for each analyte with good correlation coefficients. The detection limits （3S/N） of 2-NA, 4-NA and 31 pg.mL -1 and 26 pg.mL-1 was successfully applied to 2,4-DCA were 30pg.mL -1, respectively. Our method the determination of aniline compounds in fiver water sample with high precision and accuracy.

Multi-walled carbon nanotube as a solid phase extraction adsorbent for analysis of indole-3-butyric acid and 1-naphthylacetic acid in plant samples

In this work, a new sample pretreatment method prior to HPLC separations was developed for the determination of auxins in plant samples, Owing to its large surface area and high adsorption capacity, multi-walled carbon nanotube （MWCNT） was chosen as the adsorbent for the extraction of auxins from plant samples. In this study, two important auxins were selected as model analytes, namely indole-3- butyric acid （IBA） and 1-naphthylacetic acid （NAA）. They could be extracted and concentrated due to their π-π stacking interactions with MWCNT. Then HPLC-UV was introduced to detect IBA and NAA after sample pretreatment. Factors that may affect the enrichment efficiency were investigated and optimized. Comparative studies showed that MWCNT was superior to CI 8 for the extraction of the two analytes. Validation experiments showed that the optimized method had good linearity （0.9998 and 0.9960）, high recovery （81.4%-85.4%）, and low detection limits （0.0030 mg/L and 0.0012 mg/L）. The results indicated that the novel method had advantages of convenience, good sensitivity, high efficiency, and it was feasible for the determination of auxins in plant samples.

Metal-organic framework derived magnetic nanoporous carbon as an adsorbent for the magnetic solid-phase extraction of chlorophenols from mushroom sample

In this work, a metal-organic framework derived nanoporous carbon （MOF-5-C） was fabricated and modified with Fe3O4 magnetic nanoparticles. The resulting magnetic MOF-5-derived porous carbon （Fe304@MOF-5-C） was then used for the magnetic solid-phase extraction of chlorophenols （CPs） from mushroom samples prior to high performance liquid chromatography-ultraviolet detection. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and N2 adsorption were used to characterize the adsorbent. After experimental optimization, the amount of the adsorbent was chosen as 8.0 mg, extraction time as 10 min, sample volume as 50 mL, desorption solvent as 0.4 mL （0.2 mL × 2） of alkaline methanol, and sample pH as 6. Under the above optimized conditions, good linearity for the analytes was obtained in the range of 0.8-100.0 ng g 1 with the correlation coefficients between 0.9923 and 0.9963. The limits of detection （SIN= 3） were in the range of 0.25-0.30 ng g-1, and the relative standard deviations were below 6.8%. The result showed that the Fe304@MOF-5-C has an excellent adsorption capacity for the analytes.

碳纳米管中和器工作特性研究

针对引力波探测和地球重力场探测等高精度空间探测任务对系统精度提高的要求,从碳纳米管场发射中和器的工作稳定性和电子引出问题进行试验设计,测试了其老练前后的电流波动特性,应用Spearman秩相关检验方法对背景电场和电流波动进行相关性分析,并使用3种不同孔径的栅极对中和器引出特性进行测试,分析了栅极孔径对中和器性能影响的机理。结果表明,老练处理有助于提高中和器工作稳定性,且发射极工作背景电场与发射电流不稳定性具有强相关关系;栅极孔径对发射性能与引出性能均有影响,在试验工况下1 mm孔径栅极性能最佳。该结果可为推进系统中的中和器配置和中和器结构设计提供一定指导。

Simple and Sensitive Determination of Aromatic Acids in Coconut Water by g-C3N4@SiO2 Based Solid-phase Extraction and HPLC-UV Analysis

In this study, graphitic carbon nitride deposited silica（g-C3N4@SiO2） was prepared by simple pyrolysis of melamine on silica and then used as a solid-phase extraction（SPE） sorbent for the extraction of four representative aromatic acids including benzoic acid（BA）, salicylic acid（SA）, indolyl-3-butyricacid（IBA） and naphthalene acetic acid（NAA） in coconut water（CW） samples, g-C3N4@SiO2 exhibited an excellent adsorption capacity for the four aromatic acids, which are in the concentration range of 500--558.8 gg/g. The four aromatic acids could be directly captured by g-C3N4@SiO2 from CW samples within 5 rain. Thus, a rapid, simple and effective method for the analy- sis of four aromatic acids in CW samples was developed by coupling g-C3N4@SiO2-based SPE with high performance liquid chromatography-ultraviolet（HPLC-UV） detection. The linearity of the developed method was in the range of 20--1000 ng/mL and its limit of detection was in the range of 1.9--5.7 ng/mL, which were signi- ficantly lower than those of the reported similar methods. The intra-day and inter-day precisions（based on the relative standard deviation, n=3） of the four aromatic acids were under 9.5% and 10.4%, respectively. The developed method was applied to determining the four aromatic acids in real CW samples and the spiked recoveries varied from 81.1% to 121.8%.

Modified Coated Copper Wire as a New Fiber for SPME-GC Analysis of Some Polycyclic Aromatic Hydrocarbons

In this study for the first time, a novel copper Solid Phase Microextraction (SPME) fiber has been introduced for removal of naphthalene, phenanthrene and anthracene from aqueous solution. Copper was used as a solid support, which was at first coated by 3-mercaptopropyltrimethoxysi- lane. A stationary phase of oxidized multi walled carbon nanotube (MWCNTs)) was bonded to the surface of the copper wire. The developed SPME was characterized by IR and Scanning Electron Microscopy (SEM) and coupled to gas chromatography for separation of the analytes. Stability of the fiber, the effect of coating thickness and recovery time were optimized. The MWCNTs film thickness was about 5 μm which was perfect for a rapid mass transfer. The detection limits were at the range of 0.005 to 0.1 μg·L-1. The calibration curves were linear R2 > 0.9813 in the range of 0.01 to 5 μg·L-1. The method has been successfully applied for real samples with standard addition of 5 μL-1 of each sample. Stability study of the fiber to acid and alkali shows that it can be used for more than 50 times.

碳纳米管复合材料结合分散固相萃取-高效液相色谱-串联质谱法检测环境水样中痕量全氟化合物

以碳纳米管-二氧化硅棒复合材料为吸附剂,基于分散固相萃取法和液相色谱-串联质谱法建立了一种高灵敏、快速分析环境水样中痕量全氟化合物(PFCs)的方法。该研究选择全氟己烷磺酸、全氟庚酸、全氟辛酸、全氟辛烷磺酸、全氟壬酸和全氟癸酸6种全氟化合物为目标分析物。采用单因素优化法对影响萃取效果的重要因素进行了优化。获得的最佳条件为:吸附时间为30 min、吸附剂用量为10 mg、样品溶液pH为6、萃取过程添加NaCl浓度为1.7 mol/L、解吸溶剂为丙酮、解吸时间为4 min、解吸液的体积为4 mL。采用高效液相色谱-三重四极杆质谱联用技术对水样品中全氟化合物进行定量分析。以5 mmol/L乙酸铵和甲醇为流动相进行梯度洗脱,经Kinetex C18色谱柱(100 mm×2.1 mm, 1.7μm)分离,采用电喷雾离子源、负离子扫描模式和质谱多反应监测,实现了环境水样中6种全氟化合物的快速定性和定量分析。在优化条件下,6种全氟化合物在各自的线性范围内线性关系良好,检出限(S/N=3)为0.10~0.26 ng/L。添加500 ng/L 6种PFCs进行重复性实验,日内相对标准偏差(RSD)为2.51%~7.48%,日间RSD为3.59%~9.63%。将方法应用于自来水、桶装饮用水和河水3种实际环境水样中全氟化合物的分析,在低、中、高3个水平下,6种全氟化合物的加标回收率为72.1%~109.6%,结果满意。本方法成功地应用于实际环境水样中全氟化合物的检测,为快速、有效地检测环境水样中痕量全氟化合物提供了良好的选择。

多壁碳纳米管固相萃取净化-高效液相色谱法测定猪肉和鸡肉中的磺胺多残留

建立了多壁碳纳米管为吸附剂的固相萃取净化-高效液相色谱-紫外检测测定猪肉和鸡肉中多种磺胺类药物多残留的方法。样品采用乙腈提取，多壁碳纳米管固相萃取净化，NaH2PO4缓冲溶液（pH5.5～6.0）溶解上样，5％（v/v）丙酮-正己烷淋洗，丙酮-二氯甲烷（1：1，v/v）洗脱。色谱分离以50mmol/LNaH2PO4-乙腈（7：3，v/v）为流动相，方法的线性范围为0.01～1.00mg/L，线性相关系数大于0.998，检出限（LOD）为0.003mg/L，定量限（LOQ）为0.01mg/L。在0.02～0.2mg/kg添加范围内，9种磺胺类药物的回收率高于70％，RSD低于8％，表明多壁碳纳米管对磺胺类药物具有较强的吸附富集能力。该方法简便、准确可用于动物组织及产品中磺胺药物残留的检测。

多壁纳米碳管固相萃取测定水中的有机氯农药

对于水样中的有机氯农药的净化方法主要是采用传统的液液分配的方法,缺点是溶剂使用量和前处理复杂.近年来固相萃取及固相微萃取等技术被应用到水样中的有机污染物的测定[1,2].如利用键合在硅胶上的非极性(C18,LC18等)或极性物质(LC-CN,LC-NH2)对水中有机物进行富集,用GDX或XAD自填的固相柱的报道也很多[3,4].……

基于壳聚糖修饰碳纳米管表面铅离子印迹材料的制备及其性能研究

以壳聚糖修饰的多壁碳纳米管为基材,Pb2+为模板分子,乙烯化壳聚糖(CS)为功能单体,乙二醇二甲基丙烯酸酯(EGDMA)为交联剂,在碳纳米管表面枝接一层Pb2+印迹聚合物。采用红外光谱、热重分析和扫描电镜对聚合物进行表征和分析。结果表明,在碳纳米管上成功制备了一层15～20nm厚的Pb2+印迹聚合材料。采用原子吸收法研究此印迹聚合物的吸附性能,此印迹聚合物对Pb2+表现出特异性吸附。此印迹聚合物用作固相萃取富集材料,结合原子吸收光谱技术,成功应用于废水中Pb2+的分离及测定,回收率为94.8%～101.6%。

碳纳米管应用研究进展

碳纳米管具有特殊的导电性能、力学性质及物理化学性质等,自问世以来即引起广泛关注,近年来广泛应用于众多科学研究领域,本文综述了碳纳米管近年来在固相萃取吸附剂、催化剂、气体传感器等方面的应用研究进展。

Fe_3O_4纳米粒子修饰多壁碳纳米管的制备及在水和蜂蜜样品中痕量菊酯类农药分析中的应用

通过化学共沉淀法使Fe3 O4纳米粒子负载于酸化多壁碳纳米管（ AMWNTs）表面，得到Fe3 O4／AMWNTs磁性纳米材料。该材料具有很好的磁响应度和分散性，将其用于富集痕量拟除虫菊酯类农药残留，结果证明该复合材料对菊酯类农药的吸附性能良好。通过对影响萃取性能的几种因素如离子强度、萃取时间和解吸时间依次进行优化，在最优条件下，建立了Fe3 O4／AMWNTs磁性分散固相萃取？气相色谱测定6种菊酯类农药残留的分析方法。线性范围在0？5～50μg／L之间，相关系数（ R2）大于0？990，检出限为0？07～0？20μg／L，精密度为3？8％～8？1％。该方法用于河水、鱼塘水和两种市售蜂蜜中菊酯类农药的残留分析，回收率高于78？4％。该方法操作简便、灵敏度高，能够满足环境水样及蜂蜜样品中痕量菊酯农药残留的分析需求。

多壁碳纳米管固相萃取-气相色谱法检测蔬菜中毒死蜱、丙溴磷和三唑磷农药残留

本文以多壁碳纳米管为固相萃取材料，建立了蔬菜中毒死蜱、丙溴磷和三唑磷农药残留的GC—FPD分析方法。样品经乙酸乙酯匀浆提取后，用多壁碳纳米管SPE柱净化，以丙酮：正己烷（1：1，v／v）为洗脱剂，浓缩后用丙酮定容，再用GC—FPD进行检测。三种有机磷农药在0．0025—2．0mg／L范围内呈良好的线性关系，相关系数在0．9998～0．9999之间，回收率在83．3％-96．7％之间，方法的检出限在8．21×10^-4～1．37×10^-3mg／kg之间。将该方法推广到莴苣、番茄、豇豆、梨、香菇等9种蔬菜、水果和食用菌中毒死蜱、丙溴磷、三唑磷农药残留的测定，效果较好。

利用碳纳米管固相萃取气相色谱法对水中有机氯农药和多氯联苯的测定

研究利用碳纳米管作为固定相，萃取水中4种有机氯农药（Heptachlor、Aldrin、Dieldrin、Endrin）和5种多氯联苯（PCB052、101、138、153、180），并用GC／ECD测定。建立了碳纳米管柱SPE／GC／ECD同时测定水中4种有机氯农药和5种多氯联苯的分析方法。通过空白加标和样品基质加标实验考察了方法性能，测得碳纳米管柱萃取的方法检出限为0．10—0．27μg·L^-1，相对标准偏差为8．61％～19．3％，9种目标化合物的回收率在62％-120％之间。