Impedance Spectroscopic Measurements of Pure Gas Adsorption Equilibria on Zeolites

Physisorption equilibria of gases on inert porous solids like activated carbon or molecular sieves can be characterized by measuring the (frequency dependent) capacitance of a capacitor filled with a sample adsorbent. This quantity strongly depends not only on the physico-chemical structure of the empty adsorbent in vacuum, but also on the permanent or induced dipole moments of the molecules adsorbed and of the fluid phase. Consequently, it should be possible to determine the excess mass being adsorbed on the internal surface of a highly porous solid by measurements of the dielectric constant. The aim of this work is to show for various pure gases and adsorbents that the change of the capacitance of an adsorption system depends on the adsorbed mass. Therefore, this effect can be used to characterize porous solids and their adsorbates and, for example, to check the state or the quality of industrial adsorbents during a process on site if calibration measurements have been taken (Staudt et al., 1994, 1998).     

A Robust Electrochemical Sensor Based on Butterfly-shaped Silver Nanostructure for Concurrent Quantification of Heavy Metals in Water Samples

Heavy metals in drinking water have become a severe threat to human health. Detection of heavy metals has been achieved by electrochemical sensors that are modified with complex nanocomposites; however, reproducibility of these sensors is still a big challenge when applied in commercial settings. Here, a simple, very robust, and sensitive electrochemical sensor based on a screen-printed carbon electrode modified with butterfly-shaped silver nanostructure (AgNS/SPCE) has been developed for the concurrent determination of cadmium (II), lead (II), copper (II), and mercury (II) in water samples. The electrochemical behavior of the modified electrodes was investigated using cyclic voltammetry and differential pulse anodic stripping voltammetry. The AgNS/SPCE showed distinct peak potentials and a significant increase in the peak currents for all heavy metals, attributed to the high electrical conductivity and electrocatalytic activity of the synthesized butterfly-shaped AgNS. Moreover, the excellent stability and sensitivity towards simultaneous quantification of heavy metals have been obtained with detection limits of 0.4 ppb, 2.5 ppb, 7.3 ppb, and 0.7 ppb for Cd (II), Pb (II), Cu (II), and Hg (II), respectively. Besides, the constructed sensor was successfully applied to simultaneously quantify target heavy metals in spiked water samples. Owing to excellent sensitivity, high robustness, affordability, and fast response, the presented electrochemical sensor could be incorporated into a portable and miniaturized potentiostat device, making it a promising method for on-site water analysis.     

交流阻抗法在细胞分析中应用的研究进展

交流阻抗法作为一种新型的无标记、全程动态、实时分析方法已在细胞研究中得到了广泛应用。本文综述了基于交流阻抗法进行细胞分析的研究新进展,重点对非法拉第阻抗谱法和法拉第阻抗谱法用于细胞分析的原理及应用进行了总结,主要包括交流阻抗法在细胞形态、细胞生长、细胞增殖、细胞凋亡以及作用于细胞的药效和毒性研究中的应用,并对其发展趋势进行了展望。     

Electrochemical Impedance Spectroscopic Measurements of Sexithiophene—Effect of the Electrode Nature and the Dopant (CuCl2) Content

Electrochemical impedance spectroscopic (EIS) measurements of sexithiophene (6T) were carried out according to the Pt/6T/M sandwich structure configuration, for various electrode materials (M＝GC, ITO, Ag, Cu, Al) and for different doping levels of copper chloride (CuCl2). The results demonstrate that two types of charge transport are involved in the redox process at the electrode/6T interface and inside the bulk oligomer. The complex-plane impedance plots obtained for various doping levels of CuCl2 exhibit arc shapes. The charge-transfer resistance measured from the diagrams decreases systematically with the addition of the salt, leading to an increase of the oligothiophene conductivity.     

在线固相氧化物吸附-火焰原子吸收法测定痕量银

基于硅胶表面对碱性体系中新生成的氧化银(Ag2O)的有效吸附, 建立了流动注射-固相氧化物分离富集-火焰原子吸收法测定痕量银的方法. 当银以氧化物的形式被滞留在硅胶固相表面时, 硅胶表面的硅醇基和表面电荷有利于反应体系中新生成的Ag2O胶状沉淀的吸附, 将收集的沉淀用HNO3(10%, 体积分数)洗脱后用火焰原子吸收测定. 当进样体积为5.4 mL时, 测得的富集系数为25.5, 检出限为0.6 μg/L, 采样频率为50次/h, 线性范围为2~150 μg/L, 相对标准偏差(RSD)为2.0%(40 μg/L, n=11). 将该法用于自来水、河水、井水、雪水和山泉水中银含量的测定, 加标回收率分别为93.3%, 89.5%, 96.6%, 108.4%和102.8%.     

泥炭吸附废水中铅离子的研究

测定了泥炭吸附废水中铅离子浓度 ,为开发泥炭资源提供参考。结果表明 ,Pb2 + 离子浓度越高 ,除铅率越低 ,表观吸附量越大 ;温度越高 ,表观吸附量越大。     

液液萃取中半挥发性有机物正辛醇/水分配系数与回收率相关性分析

该文讨论了水中目标有机物的回收率与正辛醇/水分配系数之间的联系,结果表明半挥发性有机污染物在水中的回收率与正辛醇/水分配系数(lg Kow)间存在一定的规律:当lg Kow5时,回收率为16.1%~56.1%,当lg Kow5时,回收率为59.5%~124.9%;用溶解度(lg S)与89种有机污染物的回收率进行分析,得出与正辛醇/水分配系数(lg Kow)一致的结论:当lg S-0.60时,回收率为59.5%~124.9%,当lg S-0.6时,回收率为16.1%~56.1%;采用实际水样的实验室空白加标结果对所得结论进行验证,其结果显示与上述结论一致,即当污染物的lg Kow5,或者lg S-0.6时,其液液萃取的回收率为85.3%~115.9%。     

多孔有机聚合物吸附分离水体系中有机污染物研究和应用进展

有机物对水体的污染严重威胁生态环境安全和人类健康。 如何有效控制和消除水体系中的有机污染物是当前全球性热点问题之一,基于多孔材料的高效吸附是处理水体有机污染的有效方法。 多孔有机聚合物(Porous Organic Polymers,POPs)具有比表面积高、物理化学稳定性好、易修饰等特点,作为新型吸附剂在处理水体系有机污染方面具有广阔的应用前景。 本文综述了近10年来新型多孔有机聚合物对水体系中有机溶剂、农药与杀虫剂、有机染料等污染物的吸附分离研究进展。     

多孔有机聚合物在水处理中的应用

多孔有机聚合物是一类由纯有机基团构成的新型材料。 近年来,多孔有机聚合物在吸附水中污染物方面引起了人们的兴趣。 本文简要地介绍了几种多孔有机聚合物吸附水中污染物最近的研究进展,并对其吸附机理、影响因素和研究前景进行了总结与展望。     

Microanalysis of Volatile Organic Compounds (VOCs) in Water Samples – Methods and Instruments

Volatile organic compounds (VOCs), due to their toxicity and persistence in the environment, are particularly important pollutants. Some of these compounds are mutagens, teratogens or carcinogens, while others are responsible for the degradation of organoleptic parameters such as taste and odour of water. This review focuses on a number of key procedural steps in the analysis of volatile organic compounds (VOCs) in water samples. A wide spectrum of techniques for the isolation and preconcentration of the aforementioned pollutants for trace organic analysis by gas chromatography are presented and discussed. The advantages and disadvantages of these techniques are discussed and novel developments are also taken into consideration.     

DNA与5-氟尿嘧啶相互作用的电化学和谱学研究

以电位控制共价组装法制得的DNA修饰电极为工作电极, 采用循环伏安和方波脉冲伏安法, 以亚甲蓝(MB)为电活性指示剂, 研究了非电活性抗癌药物5-氟尿嘧啶(5-FU)与DNA的相互作用, 还结合紫外-可见光谱进一步研究了这种相互作用. 循环伏安测试结果表明: 5-FU与DNA在电极表面反应的过程为可逆电化学反应-化学反应偶合(EC)过程. 当扫描速度较低时, EC反应是扩散控制过程; DNA与电活性物质MB通过静电吸附相互结合, 抗癌药物5-FU与DNA通过插入作用相互结合. 本研究对于遗传工程中以DNA为靶标的药物设计有重要的意义.     

The Application of Microelectrodes for the Measurements of Trace Metals in Water

Abstract

The analytical approaches for the determination of trace concentrations of heavy metals in aquatic systems are briefly introduced. A detailed review on the recent advances of microelectrodes is presented, including the definitions, types, advantages, theory, and fabrication of microelectrodes. The application of microelectrodes on the measurements of trace metals in water is focused on the voltammetric‐, potentiometric‐, and in situ electrochemical sensors.     

多巴胺功能材料在水污染控制中的应用

多巴胺又名4-(2-乙氨基)-苯-1,2-二酚,具有官能团丰富,吸附位点多以及良好的生物相容性等众多优势,近年来,利用多巴胺研制纳米复合功能材料及环境应用是重要研究方向之一。本文从多巴胺结构特性以及自聚组装机理入手,介绍了将聚多巴胺涂布于不同基底材料进行改性,总结性能优异的多巴胺纳米复合材料的制备方法及在污水处理方面的应用进展及应用前景。     

Alternating Current Measurements in Scanning Electrochemical Microscopy,Part 2: Detection of Adsorbates

A scanning electrochemical microscope (SECM) in ac mode is used for the characterisation of the adsorption process during the hydrogen evolution reaction (HER) in sulfuric acid solution. It is shown that this technique allows quantitative analysis of the adsorption process, and measurements of the differential capacitance with the frequency as parameter are obtained. The time constant for relaxation of adsorbed hydrogen (H_ads) is approximately 2 Hz, and analysis of the Nyquist plot allows direct evaluation of the charge involved. In addition, the direct comparison of the usual electrochemical impedance data and ac‐SECM results obtained simultaneously permits characterisation of processes occurring at the surface and in solution.     

Electrochemical Dissolution of Silver Nanoparticles and Its Application in Metalloimmunoassay

This work demonstrates the use of silver nanoparticles as a simple electrochemical biolabel to induce 10⁶ signal enhancement. We propose a mechanism of measuring the silver nanoparticles on a specific screen‐printed planar carbon electrode, without the requirement for the harsh oxidant or toxic reagents described in prior‐art for gold sol methods. The possible measurement process was validated with orthogonal techniques such as UV/Vis spectroscopy, dynamic light scattering and by anodic stripping voltammetry (ASV). The findings were utilized to develop a novel electrochemical sandwich immunoassay where the analyte concentration is directly proportional to ASV oxidation peak of silver. This technique in the future is envisaged to form the foundation of a generic Point of Care platform. The assay was applied to cardiac marker: myoglobin with detection limit of 3 ng/mL.     

Electrochemical Biosensors Based on Enzymatic Reactor of Silver Solid Amalgam Powder for Measurements in Flow Systems

An enzymatic reactor based on silver solid amalgam powder was suggested as the main part of biosensors in flow systems for the first time. Biosensors were tested with following enzymes: ascorbate oxidase, glucose oxidase, catalase, tyrosinase and laccase. The current response of each biosensor was optimized with respect to the detection potential, flow rate, the injection and reactor volume. Relative standard deviation for detection with the studied enzymes was found to be in the range of 0.81–2.1 %. The biosensor with the ascorbate oxidase reactor was used for determination of ascorbic acid in the vitamin tablets Celaskon.     

尖晶石LiMn2O4中锂离子嵌入脱出过程的电化学阻抗谱研究

运用电化学阻抗谱(EIS)研究了尖晶石LiMn2O4电极的首次充放电过程. 发现EIS谱高频区域拉长压扁的半圆是由两个半圆相互重叠而成的, 分别归属于与锂离子通过固体电解质相界面膜(SEI膜)的迁移和与尖晶石LiMn2O4材料的电子电导率相关的特征. 通过选取适当的等效电路, 对实验所得的电化学阻抗谱数据进行拟合, 获得尖晶石LiMn2O4电极首次充放电过程中SEI膜电阻、电子电阻和电荷传递电阻等随电极极化电位变化的规律. 根据研究结果提出了嵌锂物理机制模型.     

Synthesis and Characterization of Flexible Hydrogel Electrodes for Electrochemical Impedance Measurements of Protective Coatings on Metal Sculptures

A novel conductive anionic hydrogel was synthesized for use as a solid electrolyte for electrochemical impedance spectroscopy (EIS) characterization of the barrier properties of protective coatings on outdoor metalworks, such as bronze sculptures. The AMPS‐co‐PAA hydrogel was soaked in a variety of aqueous salt solutions and characterized by swelling capacity and conductivity in order to determine the most appropriate gel/liquid electrolyte combination for use on culturally significant objects. K₂PIPES‐equilibrated hydrogels were selected as the preferred electrodes for this particular application and were used to measure the impedance of a coated substrate, yielding spectra similar to those from standard liquid cells.     

大黄酚的电化学行为及其应用研究

大黄酚在０．１５ｍｏｌ／Ｌ ＨＡｃ－ＮａＡｃ（ｐＨ４．９）底液中，出现一灵敏的示波极谱导数峰，峰电位为－０．４５Ｖ（ｖｓ，ＳＣＥ），峰电流与大黄酚浓度在２．０×１０＾－７－５．０×１０＾－６ｍｏｌ／Ｌ范围内成线性关系，检测限为２．０×１０＾－６ｍｏｌ／Ｌ。用于生药大黄中大黄酚的测定，回收率为９２．４％－１０８．４％。用多种电化学手段研究体系的电化学行为，测得电极反应电子数ｎ＝２。体系具有吸附性，并     

Spectroscopic Measurements of Physiological Elements in Microdialysis Samples from Rat Brain,Flowering Plum Fruit and Pea

IntroductionMicrodialysisisanimportantbioanalyticalsamplingtechnique,whichinvolvestheimplantationofasmallprobeofsemipermeablemembraneintothesubjecttobestudiedl.Themethodisminimallyinvasiveandverysuitableforstudyingparameterssuchasphysiologicalelement...