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1.
金属络合物体系极谱数据的计算机分析方法 总被引:1,自引:3,他引:1
介绍了一种用于金属络合物体系多级稳定常数测定的新型极谱研究方法。运用电化学原理,推导出适合于金属络合物体系极谱研究的数学方程。该方程表明实验得到的金属络合物体系峰电位的移动和峰电流的变化是与溶液中自由金属离子浓度变化有关。依据实验得到的极谱峰电位的移动和峰电流的变化,建立合适的金属络合物体系模型。用计算机分析程序,求解体系的质量平衡方程,拟合络合物形成曲线,得到金属络合物体系的多级稳定常数和形态分布图。 相似文献
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《Environmental Modelling & Software》2005,20(3):353-359
Speciation modeling is an essential tool to estimate the chemical composition of an aqueous sample and to assess the bioavailability and potential risks associated with metal contamination. It is also an indispensable alternative for quantifying the metal speciation when analytical techniques are not available. In this study, we tested the effectiveness of two models, WinHumicV and the Non-Ideal Competitive Adsorption (NICA)-Donnan model, in predicting the amount of Cd2+ and Pb2+, which were originally measured by anodic stripping voltammetry (ASV). In general, with its default parameters, WinHumicV satisfactorily estimated the free Cd concentrations. For Pb, at high pH the model predictions were lower than the ASV measurements. The discrepancy between the measured and predicted free Pb concentrations may be attributed to the uncertainty of stability constants in WHAM model V for metal–DOC interactions, or the possible overestimation of free metals by ASV at high pH. Using the published generic parameters for fulvic acid (FA), the consistent NICA-Donnan model also made predictions comparable to the experimental data when Al and Fe competition was taken into account in the model. The agreement of model predictions and experimental data demonstrates that both models provide reasonable predictions of the metal speciation in soil solutions. However, the results stress the requirement of estimates or measurements of Al and Fe concentrations in soil solution speciation to provide reasonable estimates of trace element speciation. 相似文献
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导电聚合物电极同时测定痕量铜、铅、镉、锌 总被引:1,自引:0,他引:1
使用一种新型导电聚合物电极作为工作电极,采用阳极溶出伏安法通过同位镀铋对导电聚合物电极进行修饰,实现了痕量铜、铅、镉、锌的同时测定.比较了导电聚合物电极和丝网印刷碳电极的性能,研究了预富集时间和不同介质对重金属离子测定的影响规律.结果表明:铜、铅、镉、锌在铋膜修饰的导电聚合物电极上分别在0.05 V、-0.55 V、-0.80 V、-1.10 V产生灵敏的电位溶出峰,峰高与离子浓度线性相关,最低检测限分别可达到0.5 μg/L、1 μg/L、1 μg/L和0.5 μg/L.在检测重金属离子方面,导电聚合物电极比丝网印刷碳电极更加灵敏和稳定,为一次性电化学传感器的发展提供了良好的基础. 相似文献
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A novel electronic tongue combined MLAPS with stripping voltammetry for environmental detection 总被引:1,自引:0,他引:1
A kind of integrated electronic tongue device has been developed, which includes a multiple light-addressable potentiometric sensor (MLAPS) and two groups of electrochemical electrodes. MLAPS is based on chalcogenide thin film for the simultaneous detection of Fe(III) and Cr(VI) ions while two groups of electrochemical electrodes, respectively, detect other heavy metals using stripping voltammetry (SV) including anodic and cathode stripping voltammetry. The methods are more convenient for the simultaneous detection of heavy metal in wastewater or seawater and can improve the detection speed and measurement accuracy to many heavy metals. Accordingly a kind of potable electronic tongue instrument to work on-line is also developed. 相似文献
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P. R. M. Silva M. A. El Khakani B. Le Drogoff M. Chaker A. K. Vijh 《Sensors and actuators. B, Chemical》1999,60(2-3):161-167
Mercury-electroplated-Ir microelectrode array based sensors have been developed; their electroanalytical performance is investigated for the simultaneous detection of ultratraces of Pb, Cd and Zn. Two Ir microelectrode array geometries were used, namely: (i) an array of 1089 microelectrodes of 3-μm diameter and (ii) an array of 1764 microelectrodes of 6-μm diameter. Prior to the Hg electroplating, the arrays were systematically characterized by means of cyclic voltammetry at various scan rates ranging from 5 to 500 mV s−1 and found to exhibit a steady-state voltammetric behavior. The effect of the Hg charge (over a range as wide as 0.05–40 mC) on the electroanalytical performance (net peak current, peak potential and peak width) of the metal trace sensors has been systematically studied by using square wave anodic stripping voltammetry (SWASV). It is clearly shown that the net peak current not only depends on the magnitude of Hg charge, but also presents a maximum value for an optimum Hg charge. Optimum Hg charges of 4 and 15 mC were identified for the 3- and 6-μm diameter Ir microelectrodes, respectively. At the optimum Hg charges, calibration plots demonstrated good linearity for the three metal traces over a concentration range as wide as (100 ppt–1 ppm). By increasing the preconcentration time from 5 to 20 min, it is shown that the detection limit of metal ultratraces can be decreased from 100 to 20 ppt. 相似文献
9.
Zhiwei Am Eric Pei-Ming Jaephil Paul L. Chong H. 《Sensors and actuators. B, Chemical》2008,134(1):18-24
This paper presents an environmentally friendly disposable heavy metal ion sensor for in situ and online monitoring in the nature and physiological systems. The miniaturized sensor chip consists of a non-toxic microfabricated bismuth (Bi) working electrode that replaces the conventional mercury electrodes, an integrated Ag/AgCl reference electrode, a gold counter electrode, and microfluidic channels. In this work, the electrochemical behavior of the Bi working electrode was characterized in several non-deaerated buffer solutions using cyclic voltammetry. The detection and quantification of Pb (II) and Cd (II) were statically performed using anodic stripping voltammetry inside the microchannels, in the Pb (II) concentration range of 25–400 ppb (R2 = 0.991) with limit of detection of 8 ppb for 60 s deposition, and in the Cd (II) concentration range of 28–280 ppb (R2 = 0.986) with limit of detection of 9.3 ppb for 90 s deposition. Particularly, the applications of this sensor chip have been reported with the examples of in situ measurement of Cd (II) concentration in soil pore and ground water and online direct measurement of Cd (II) concentration in cell culture media in its native environment. 相似文献
10.
Wooseok JungAuthor VitaeAm JangAuthor Vitae Paul L. BishopAuthor VitaeChong H. AhnAuthor Vitae 《Sensors and actuators. B, Chemical》2011,155(1):145-153
This paper presents a reusable polymer lab chip sensor for continuous and on-site heavy metal monitoring in nature. In particular, detection of lead (Pb(II)), which is the most common heavy metal pollutant, has been performed using the proposed lab chip sensor. The miniaturized lab chip sensor consists of a microfabricated silver working electrode that replaces the conventional mercury and bismuth electrodes, an integrated silver counter and quasi-reference electrode, and microfluidic channels. The proposed sensor targets on-site environmental monitoring in a continuous fashion without disturbing or contaminating the sensing environment when it is reused. The reusability of the miniaturized lab chip sensor was characterized through forty-three consecutive measurements in non-deoxygenating standard solutions inside the microchannels using square-wave anodic stripping voltammetry (SWASV). With only 13.5 μL of sample volume the sensor chip showed a correlation coefficient of 0.998 for the Pb(II) concentration range of 1-1000 ppb with the limit of detection of 0.55 ppb at 300 s deposition time. The peak potentials during the forty-three consecutive SWASV measurements showed a relative standard deviation of 1.0%, with a standard deviation of 0.005 V. The high repeatability and linearity of the sensor over the large, three orders of magnitude, dynamic range of 1-1000 ppb showed that the developed sensor chip can be reused for a variety of on-site measurements such as for soil pore water or groundwater, using only micro-volumes. 相似文献
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In this paper a novel process to bond and, at the same time, to electrically connect a silicon wafer to a glass wafer is presented. It consists of a low temperature anodic bonding process between silicon and glass by using a glass wafer with etched channels in order to contain metal tracks. The glass-to-silicon anodic bonding process at low temperatures (not exceeding 300°C) assures a strong mechanical link (Berthold et al. in Transducers 1999, June:7–10, 1999). The electrical contacts between the metal pads on the backside of a silicon wafer and the metal pads on the glass wafer are achieved by sintering and diffusion of metals due to a kind of thermo compression bonding. This bonding method permits a high vertical control due to a well-controlled etching of the cavity depth and to the thickness precision of both metallization (pads on silicon wafers and metal tracks on glass wafer). This IC-processing compatible approach opens up the way to a new electrical connection concept keeping, at the same time, a strong mechanical bond between glass and silicon wafers for an easier fabrication of a more complex micro-system. 相似文献
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Howard S. Manwaring 《Neural computing & applications》1994,2(3):168-178
A comparison is made between backpropagation and general regression neural networks for the prediction of parts per billion lead concentration when used to process data obtained from digested curry powder by the electrochemical analysis method of differential pulse, anodic stripping at a thin film mercury electrode (TFME). Two data sets are used, one requiring the net to classify an unknown analytical data vector into one of a number of previously learnt concentrations, and one requiring the net to predict the probable concentration of an unknown sample by interpolation of the already learnt concentrations. For both of these data sets the general regression neural network is shown to train faster and to provide results superior to those obtained by backpropagation. 相似文献
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多孔阳极氧化铝经化学修饰后吸附细胞色素C,制备了过氧化氢生物传感器电极。多孔阳极氧化铝通过电化学和化学腐蚀阻挡层后,用两步无电沉积方法制备了纳米金修饰的多孔阳极氧化铝电极,再在含有L-半胱氨酸的细胞色素C的溶液中通过吸附制备细胞色素C电极。用循环伏安法和计时电流法测试细胞色素C电极的电化学性能及催化对过氧化氢的还原。结果表明,包覆的细胞色素C电极显示较好的稳定性,在扫描速度为80 mV/s时于-50 mV、-190 mV附近出现一对稳定的氧化还原峰。该电极对过氧化氢具有良好的电催化还原性能,在1.5×10-5 mol/L~4.8×10-4 mol/L浓度范围内,电流与浓度呈良好的线性关系。多孔阳极氧化铝经化学修饰后,可应用于生物传感器。 相似文献
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Ian Streeter Gregory G. Lidong Richard G. Compton 《Sensors and actuators. B, Chemical》2008,133(2):462-466
Cyclic voltammetry is recorded of the oxidation of ferrocyanide on a glassy carbon electrode modified with multiple layers of single-walled carbon nanotubes. The current response is interpreted in terms of semi-infinite planar diffusion towards the macro-electrode surface and in terms of oxidation of the electroactive species trapped in pockets in between the nanotubes. A thin layer model is used to illustrate the effects of diffusion within a porous layer. It is found that a semi-infinite planar diffusion model alone is not appropriate for interpreting the kinetics of the electron transfer at this electrode surface. In particular, caution should be exercised in respect of comparing voltammetric peak-to-peak potential separations between naked electrodes and nanotube-modified electrodes for the inference of electrocatalysis via electron transfer via the nanotubes. 相似文献
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Bismuth film electrodes (BiFEs) have a potential to replace toxic mercury used most frequently for determination of heavy
metals (Cd, Pb, Zn) by anodic stripping voltammetry. We prepared a graphite disc electrode (0.5 mm in diameter) from a pencil-lead
rod and developed a nitrogen doped diamond-like carbon (NDLC) microelectrode array consisting of 50,625 microdiscs with 3 μm
in diameter and interelectrode distances of 20 μm on a highly conductive silicon substrate as a support for BiFEs. The disc
graphite BiFE was used for simultaneous determination of Pb(II), Cd(II) and Zn(II) by square wave voltammetry (SWV) in an
aqueous solution. We found the optimum bismuth-to-metal concentration ratio in the solution to be 20. The dependence of the
stripping responses on the concentration of target metals was linear in the range from 1 × 10−8 to 1.2 × 10−7 mol/L. Detection limits 2.4 × 10−9 mol/L for Pb(II), 2.9 × 10−9 mol/L for Cd(II) and 1.2 × 10−8 mol/L for Zn(II) were estimated. A bismuth-plated NDLC microelectrode array was used for Pb(II) determination by differential
pulse voltammetry (DPV) in an aqueous solution. We found that the stripping current for bismuth-plated NDLC array was linear
in the concentration range of Pb(II) from 2 × 10−8 to 1.2 × 10−7 mol/L. The detection limit 2.2 × 10−8 mol/L was estimated from a calibration plot. 相似文献
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重金属捕集剂二甲基二硫代氨基甲酸对6种重金属螯合固化性能的量子化学研究 总被引:1,自引:0,他引:1
为探讨二甲基二硫代氨基甲酸盐螯合重金属离子的作用机理,本文采用密度泛函理论,在B3LYP/6-31++G(d,p)和B3LYP/LanL2DZ混合基组水平上,分别计算了二甲基二硫代氨基甲酸离子(DDC-)和铬、铜、钴、锌、铁、镉6种重金属离子形成配合物的前线轨道能级、配位能△E、考虑基组重叠误差后的配位能△EBSSE、零点振动能校正后的配位能△EZPE及自然电荷分布。研究结果表明:上述二甲基二硫代氨基甲酸配合物的稳定性与能级差△ε及配位能△EBSSE、△EZPE的绝对值密切相关,△ε及△EBSSE、△EZPE的绝对值越大,配合物越稳定。6种二甲基二硫代氨基甲酸重金属配合物的稳定性由大到小的顺序为:[CrDDC]2+>[CuDDC]+>[CoDDC]+>[ZnDDC]+>[FeDDC]+>[CdDDC]+。在形成配合物的过程中,电子从配体DDC-流向重金属离子,电荷转移越多,配位能的绝对值越大。 相似文献
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Porous polycrystalline silicon: a new material for MEMS 总被引:4,自引:0,他引:4
A new technique for the fabrication of thin patterned layers of porous polycrystalline silicon (polysilicon) and surface micromachined structures is presented. First, a multilayer structure of polysilicon between two layers of low-stress silicon nitride is prepared on a wafer of silicon. Electrochemical anodization with an external cathode takes place in an RF solution. A window in the outer nitride layer provides contact between the polysilicon and the HF solution; the polysilicon layer contacts the substrate through openings in the lower silicon nitride layer (remote from the upper windows). Porous polysilicon growth in the lateral direction is found at rates as high as 15 μm min-1 in 12M (25%, wgt) HF to be controlled by surface-reaction kinetics. A change in morphology occurs when either the anodic potential is raised or the HF concentration is decreased, causing the polysilicon to be electropolished. The etch front advances proportionally to the square root of time as expected for a mass-transport-controlled process. Similar behavior is observed in HF anodic reactions of single-crystal silicon. Dissolution of the polysilicon layer is confirmed using profilometry and scanning electron microscopy. Enclosed cavities (chambers surrounded by porous plugs) are formed by alternating between pore formation and uniform dissolution. Porous polysilicon also forms over a broad-area layer of polycrystalline silicon that has been deposited without overcoating the silicon wafer with a thin film of silicon nitride. The resulting porous layer may be useful for gas-absorption purposes in ultrasonic sensors 相似文献
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Harutaka Mekaru 《Microsystem Technologies》2014,20(6):1103-1109
Metal nanostructures are used as wire grids for liquid crystal displays and lighting-receiving surface electrodes of solar cells. They are also integrated in emerging devices for chemical and biomedical detection and analyses carried out under various research and development programs. Currently, the mainstream fabrication method of metal nanostructures needs many manufacturing processes including patterning and metallization technologies. Here, our high-temperature nanoimprint technology for glass materials was applied to metals, which led to the development of technology to transfer nanopatterns onto a metal foil using a quartz mold. Although the glass transition temperature does not exist in metal but plastic deformation of metal is possible if the metal is made to re-crystallize at a high-temperature, but kept below its melting point. In our experiment, Al, Ag, and Cu foils of 100 μm thickness were bonded on a glass substrate of 1 mm thickness using an intermediation layer of the same metal. After that, a heated quartz mold was pressed against each metal foil, and nano-patterning was carried out. Within the limits of the specifications of a used thermal nanoimprint system, the optimal imprint temperature for Al, Ag, and Cu foils was 500, 600, and 650 °C respectively. For all metals the imprint pressure and holding time were set as 20 MPa and 1 h. As a result of trial experiments, on the three kinds of metal foils we succeeded in forming line/space with a minimum linewidth of 350 nm; and concave and convex square dotted patterns with a minimum width of 500 nm. This technique required imprint pressure less than used in conventional direct-nanoimprinting at the room temperature. With this technique of nanofabrication, molds with a low mechanical strength could be used. 相似文献
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A promising electrochemical biosensor was developed by electrodeposition of palladium nanoclusters on polyfuran film modified platinum electrode. This biosensor electrode was used to determine some catecholamines, namely dopamine, epinephrine and norepinephrine, ascorbic acid and paracetamol. The method of formation of the polymer film and deposition of Pd particles plays a key role in the electroactivity of the resulting hybrid material. This sensor effectively resolved the overlapping anodic peaks of ascorbic acid (AA), dopamine (DA) and paracetamol (ACOP) into three well-defined voltammetric peaks in differential pulse voltammetry analysis. The detection limit of DA in the absence and presence of AA and ACOP are eventually the same which indicates that the oxidation processes of DA, AA and ACOP are independent and that the simultaneous measurements of the three analytes are possible without interference. The electrodeposition of Pd on polyfuran improved exceptionally the detection limit about four decades. Moreover, diffusion coefficient measurements confirmed the fast electron transfer kinetics of the electrochemical oxidation of the analyte molecules at the sensor/solution interface. It is very interesting to note that the electrocatalytic effect of PF/Pd composite has been increased to be sometimes 21 times that of the pristine PF which has been considered for a long time to be of low conductivity and attracted low attention as a result of the difficulty of its formation and poor conductivity. 相似文献