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。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。纳米技术和纳米材料的发展为开发固相萃取材料带来新契机。纳米材料是指尺寸大小在从1～100m之间物质。与普通的块体材料相比,纳米材料具有较大的比表面,因而有可能具有较大吸附容量。纳米材料在环境有机污染物分离富集方面的应用研究才刚刚开始。本文主要就纳米碳管对水样中的有机氯农药进行研究,优化固相萃取条件。     

Multiwalled Carbon Nanotubes: Adsorbent for Ruthenium from Aqueous Solution

Journal of Radioanalytical and Nuclear Chemistry - This paper describes the adsorption behavior of ruthenium on multi walled carbon nanotubes (MWCNTs) from aqueous solution. The adsorption behavior...     

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62～0%之间.     

Simultaneous Determination of Cyanazine, Chlorotoluron and Chlorbenzuron in Environmental Water Samples with SPE Multiwalled Carbon Nanotubes and LC

In this paper, a new method based on solid-phase extraction with multiwalled carbon nanotubes as the packed materials for sensitive determination of cyanazine, chlorotoluron and chlorbenzuron in environmental water samples was demonstrated. Related parameters that may influence the enrichment efficiency of multiwalled carbon nanotubes such as the kind and volume of elute, sample flow rate, sample pH, and volume of the water samples were investigated. Under the optimum conditions, the detection limits of cyanazine, chlorbenzuron and chlorotoluron were 0.015, 0.012, 0.034 ng mL⁻¹, respectively. The experimental results indicated a good linearity (R ² > 0.9947) over the concentration range of 0.4–40 ng mL⁻¹ for cyanazine and chlorotoluron, and 0.8–80 ng mL⁻¹ for chlorbenzuron. The relative standard deviations of the three analytes were 3.54, 1.55 and 1.38%, respectively. The established method also was applied to the analysis of the real-world water samples and excellent achievements were obtained with average spiked recoveries from 87.8 to 110.1%. All the results indicated that this procedure could allow the simultaneous determination of these three compounds in environmental water samples at trace levels.     

Application of SPE Using Multi-Walled Carbon Nanotubes as Adsorbent and Rapid Resolution LC-MS-MS for the Simultaneous Determination of 11 Triazine Herbicides Residues in River Water

A method for the simultaneous determination of 11 triazine herbicides residues in river water has been developed. It involves solid-phase extraction (SPE) pretreatment step and rapid resolution liquid chromatography-tandem mass spectrometry (RRLC-MS-MS). In the SPE pretreatment step, the adsorptive performance of MWCNTs material as SPE adsorbent and the elution capability of five kinds of solvents were investigated; in the LC separation step, a rapid resolution high throughput LC column, was used and the gradient elution mode adopted. The linear correlation coefficients (r ²) of the method for 11 target analytes varied between 0.9930 and 0.9980, the mean recoveries were in the range of 73.0 and 98.0% with relative standard deviations (RSD) 2.6 ~ 4.2%, the method detection limits (MDL) were all below 0.1 ng L^?1. An expanded uncertainty of not more than 20% was estimated for each analyte at the spiked concentration of 4.0 μg L^?1. The proposed method was applied to the determination of the residue concentrations of 11 pollutants in Songhuajiang River water.     

枪头式羧基化多壁碳纳米管固相萃取/高效液相色谱测定饮用水中双酚类化合物

该文建立了一种枪头式羧基化多壁碳纳米管固相萃取/高效液相色谱检测饮用水中5种双酚类化合物的分析方法.系统考察了碳纳米管的种类和用量、样品溶液pH值、洗脱剂的种类和用量对方法回收率的影响.在最优实验条件下,双酚A(BPA)、双酚E(BPE)、双酚F(BPF)、双酚Z(BPZ)和四甲基双酚A(TMBPA)在2.2～220μ...     

Exploring Multiwalled Carbon Nanotubes for Naproxen Detection

The electrochemical oxidation of naproxen was investigated at a multiwalled carbon nanotube (MWCNT)‐modified electrode. A decrease (200 mV) in the overpotential of the naproxen oxidation reaction and considerable (4‐fold) current increase (compared to the bare glassy‐carbon electrode) was observed. Two one‐electron transfers were verified at both bare and MWCNT‐modified electrodes and thus a new mechanism for the electrochemical oxidation of naproxen is proposed. Indicative of a mass transport regime that includes a thin‐layer diffusional process (entrapment of naproxen species within the MWCNT film) is presented as a possible explanation for the lowered oxidation potential and substantial current increase. The anti‐fouling properties of MWCNTs on the amperometric detection of naproxen using a batch‐injection analysis (BIA) system is demonstrated.     

Use of Mercury Film Glassy Carbon Electrode Modified with Multiwalled Carbon Nanotubes in Electrochemical Analysis of DNA

Mercury film plated on a glassy carbon electrode modified with multiwalled carbon nanotubes (MF/MWNTs/GCE) was used for the analysis of single (ss) and double stranded (ds) DNA, as well as for Jurkat genomic DNAs methylated to different degrees. The results indicated that the DNA molecules adsorbed quite strongly on the MF/MWNTs/GCE surface allowing ex situ adsorption and produce well developed peaks (due to cytosine and adenine) by using adsorptive stripping (Ads, ex situ) square wave voltammetry (SWV). Also, SWV of Jurkat DNA mixtures methylated to different degrees revealed a linear decrease of the peak height with increasing methylation indicating an increase of structural rigidity.     

Use of Cationic Surfactants Film Carbon Paste Electrodes Modified with Multiwalled Carbon Nanotubes in Electrochemical Analysis of dsDNA

Direct electrochemistry of dsDNA based on the enhancement effect of cationic surfactants such as dodecyltrimethylammonium bromide (DTAB) and tetradecyltrimethylammonium bromide (TTAB) was achieved by using a carbon paste electrode modified with multiwalled carbon nanotubes (MWCNTs/CPE) as the basal electrode. The results indicated that the dsDNA molecules have been adsorbed quite strongly on the cationic surfactants’ film and very well developed peaks which were attributed to the oxidation of guanine residues on the dsDNA molecule structure were obtained from both electrodes. The electrochemical behavior of dsDNA at the surface of the modified electrodes was also evaluated. Based on the signal of guanine, under the optimal conditions, very low levels of dsDNA were detected following short accumulation times with detection limits of 0.650 mg L^?1 and 0.119 mg L^?1 for DTAB/MWCNTs/CPE and TTAB/MWCNTs/CPE, respectively.     

Multiwalled Carbon Nanotubes Encased in Ruthenium Oxide Film as a Hybrid Material for Neurotransmitters Sensor

A hybrid film (MWCNTs‐RuO_x?nH₂O) which contains multiwalled carbon nanotubes (MWCNTs) along with the incorporation of ruthenium oxide (RuO_x?nH₂O) has been synthesized on glassy carbon electrode (GCE), gold (Au), indium tin oxide (ITO) and screen printed carbon electrode (SPCE) by potentiostatic methods. The presence of MWCNTs in the hybrid film enhances surface coverage concentration (Γ) of RuO_x?nH₂O to ≈2100%. The surface morphology of the hybrid film deposited on ITO has been studied using scanning electron microscopy and atomic force microscopy. These two techniques reveal that the RuO_x?nH₂O incorporated on MWCNTs. Electrochemical quartz crystal microbalance study too reveals the incorporation of MWCNTs and RuO_x?nH₂O. The MWCNTs‐RuO_x?nH₂O hybrid film exhibits promising enhanced electrocatalytic activity towards the biochemical compounds such as epinephrine and norepinephrine. The electrocatalytic responses of these analytes at RuO_x?nH₂O, MWCNTs and MWCNTs‐RuO_x?nH₂O hybrid films have been measured using cyclic voltammetry. The obtained sensitivity values from electrocatalysis studies of analytes for MWCNTs‐RuO_x?nH₂O hybrid film are higher than the RuO_x?nH₂O and MWCNTs films. Finally, the flow injection analysis has been used for the amperometric studies of analytes at MWCNTs‐RuO_x?nH₂O hybrid film modified SPCEs.     

Hemin Functionalized Multiwalled Carbon Nanotubes as a Matrix for Sensitive Electrogenerated Chemiluminescence Cholesterol Biosensor

Based on hemin‐MWCNTs nanocomposite and hemin‐catalyzed luminol‐H₂O₂ reaction, a sensitive electrogenerated chemiluminescence (ECL) cholesterol biosensor was proposed in this paper. Firstly, hemin‐MWCNTs was prepared via π–π stacking and modified on the surface of GCE. Subsequently, cholesterol oxidase (ChOx) was adsorbed on the modified electrode to achieve a cholesterol biosensor. Hemin‐MWCNTs nanocomposite provided the electrode with a large surface area to load ChOx, and endowed the nanostructured interface on the electrode surface to enhance the performance of biosensor. The biosensor responded to cholesterol in the linear range from 0.3 µM to 1.2 mM with a detection limit of 0.1 µM (S/N=3).     

Aqueous Dispersions of Thin Multiwalled Carbon Nanotubes

Aqueous dispersions of thin multiwalled carbon nanotubes stabilized by surface-active substance Triton X-100 were studied. The concentration of tubes depended on the surfactant: tubes weight ratio and reached 1.67 g/l at ratios of (2.0–2.3): 1.0. The diameter and length distributions of nanotubes were different in the dispersions and precipitates. A functional relation between the diameter and the ratio between the length and diameter was found for nanotubes in colloidal solution: the thickest tubes had the smallest length, and the length of the thinnest tubes was maximum.     

A New Indirect Electrochemical Method for Determination of Ozone in Water Using Multiwalled Carbon Nanotubes

A new electrochemical methodology has been developed for the detection of ozone using multiwalled carbon nanotubes (MWCNT). The method presented here is based on the reaction of ozone with indigo blue dye producing anthranilic acid (ATN). The electrochemical profile of ATN on an electrode of glassy carbon (GC) modified with MWCNT showed an oxidation peak potential at 750 mV vs. Ag/AgCl. An analytical method was developed using differential pulse voltammetry (DPV) to determine ATN in a range of 50–400 nmol L^?1, with a detection limit of 9.7 nmol L^?1. Ozonated water samples were successfully analyzed by GC/MWCNT electrode and the recovery procedure yielded values between of 96.5 and 102.3 %.     

多壁碳纳米管-固相萃取分析有机磷农药残留

建立了多壁碳纳米管为吸附剂的固相萃取净化和火焰光度检测气相色谱法测定蔬菜中16种有机磷农药的方法.采用双柱双检测器进行定性和定量分析.建立了水相和有机相上样两种净化体系.水相上样时采用pH 5.0醋酸-醋酸钠缓冲体系,真空抽干除水,二氯甲烷为洗脱剂,只有9种农药的回收率>75%.对于正己烷溶解药物,丙酮-正己烷(5: 5,V/V)作洗脱剂的有机相净化体系,16种农药回收率均>75%.本研究提出的有机相上样净化体系用于黄瓜、卷心菜、韭菜、生姜和洋葱等样品的净化,效果良好,表明多壁碳纳米管具有较强的吸附和去除色素的能力,可以克服色素对测定的干扰.     

超支化聚酯修饰多壁碳纳米管

将碳纳米管先用V(H2SO4)∶V(HNO3)=3∶1混合溶液进行处理,再用V(H2SO4)∶V(H2O2=4∶1的混合溶液进一步酸化,制得含有羧基的碳纳米管。将羧基化碳纳米管与二氯亚砜反应使碳纳米管连接酰氯基团,利用酰氯基团与超支化聚酯上的羟基反应,将超支化聚酯接到碳纳米管的表面上,实现了碳纳米管的表面修饰。利用红外光谱、拉曼光谱、透射电镜观察分析测试结果表明,超支化聚酯以共价键形式连接到碳纳米管的表面。热失重分析结果表明,修饰密度为每321个C原子连接1个H20分子,每842个C原子上连接1个H40分子。修饰后的碳纳米管在有机溶剂中的溶解性能明显提高。     

Epoxy Nanocomposites Modified with Functionalized Multiwalled Carbon Nanotubes

Russian Journal of Applied Chemistry - Multiwalled carbon nanotubes were modified by interaction with γ-aminopropyltriethoxysilane and were dispersed in an epoxy compound. The properties of...     

Protein Profiles of Human Serum by SELDI-TOF-MS with Multiwalled Carbon Nanotubes as Absorbent

The present paper describes a biomarker capturing strategy based on the enrichment efficiency of multiwalled carbon nanotubes (MWCNTs) for peptides and proteins from human serum. The method is shown to enrich proteins/peptides, and the captured molecules were profiled using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS). Mass spectra of the MWCNTs-treated human serum samples showed a significant enrichment of proteins by MWCNTs. Preliminary results indicated a good level of reproducibility in serum profiles with coefficients of variation (CVs) on signal intensity ranging from 8.9% to 25.2%. The developed method holds promise for improving the discovery of low-abundance serum biomarkers.     

多壁碳纳米管负载铂的甲苯加氢脱芳催化剂

以多壁碳纳米管(CNTs)为载体制备了负载型Pt催化剂Pt/CNTs并将其用于催化甲苯加氢脱芳(HDA)反应.结果表明,在1.0%Pt/CNTs催化剂上,在0.4MPa,373K,PhCH3/H2摩尔比=6/94和GHSV=120L/(h.g)的反应条件下,甲苯转化率可达100%,比反应速率为0.0523mmol/(s.m2),分别是γ-Al2O3和AC负载各自最佳Pt负载量催化剂1.4%Pt/γ-Al2O3和2.4%Pt/AC上相应值的1.17和1.18倍.甲苯加氢产物全部为甲基环己烷,其他可能的加氢产物均在气相色谱检测限以下.催化剂的表征研究揭示,用CNTs代替γ-Al2O3或AC作为载体并不会引起所负载Pt催化剂上甲苯HDA反应的表观活化能发生明显变化.与γ-Al2O3或AC负载的相应催化剂相比,一方面,CNTs负载的Pt催化剂易于在较低温度下还原活化,并且其工作态催化剂表面催化活性Pt物种(Pt0)所占表面Pt摩尔分率有所提高;另一方面,CNTs负载的Pt催化剂对H2具有较高的吸附/活化和储存能力.这些促进效应对催化剂HDA活性的提高都有重要贡献.     

碳纳米管负载/促进的Mo-Co加氢脱硫催化剂

 以多壁碳纳米管(CNT)为载体制备了负载型Mo-Co/CNT,并将其用于噻吩HDS反应. 结果表明,在n(C4H4S)/n(H2)= 2.3/97.7, GHSV=2200 ml/(g·h),p=0.1 MPa和T=623 K的条件下,在7.2%(Mo-Co)/CNT催化剂上,噻吩HDS的比反应速率可达到0.64·10-3s-1,分别是9.7%(Mo-Co)/γ-Al2O3和16.9%(Mo-Co)/AC催化剂上的1.68和2.28倍. 对比研究结果表明,用CNT代替γ-Al2O3或AC并不引起催化剂上噻吩HDS反应的表观活化能发生明显变化. 与Mo-Co/γ-Al2O3或Mo-Co/AC催化剂相比,一方面,Mo-Co/CNT催化剂更易在较低温度下还原活化,并导致工作态催化剂表层活性Mo物种(Mo4+)在总Mo量中所占比例明显提高; 另一方面,Mo-Co/CNT催化剂对H2具有更强的吸附和活化能力. 这两个因素对提高催化剂活性都有重要贡献.     

Oxidized Multi-Walled Carbon Nanotubes as SPE Sorbent for Determination of Mefenacet and Its Degradation Products Residues in Water Samples by RRLC-UV-ESI-MS

A new method was developed for the analysis of herbicide mefenacet (MN) and its three photolysis degradation products namely hydroxylbenzothiazole (HBT), N-methylaniline (N-MA) and 2-benzothiazoloxyacetic acid (2-BAA) in water samples by rapid resolution liquid chromatography coupled with UV detection and electrospray ionization mass spectrometry. In the SPE pre-concentration step, the adsorptive potential of oxidized multi-walled carbon nanotubes for the extraction of these four target analytes was investigated for the first time. Parameters influencing the extraction efficiency, such as sample flow-rate, eluent volume and sample volume, were examined. The mean recoveries were between 85.6 and 101.4% and relative standard deviations were between 3.0 and 9.2%. The limits of detection obtained were 0.02 μg L^?1 for MN and 2-BAA and 0.04 μg L^?1 for HBT and N-MA. The proposed method was applied to monitor the residual concentrations of these four target analytes in 39 real water samples collected from April to July of 2009.