排序方式: 共有77条查询结果,搜索用时 15 毫秒
51.
《Analytical letters》2012,45(4):593-598
Abstract The nickel hydroxide–modified nickel (NMN) electrode was prepared by cyclic voltammetry. The modified electrode exhibited better catalytic effect toward electrochemical oxidation of methane in 1.0 mol · L?1 NaOH solution. The catalytic activation of nickel hydroxide on the nickel electrode surface was investigated in different supporting electrolyte solutions by the cyclic voltammetry method in detail, and the related electrochemical oxidation of methane at the NMN electrode was first proposed by amperometric i‐t curve method under the experiment conditions. The results indicated that in the 1.0 mol · L?1 NaOH solution, the anodic peak current increased with the increased concentration of methane. 相似文献
52.
Isabela M. Morita Gabriela M. Araújo Lucia Codognoto 《International journal of environmental analytical chemistry》2013,93(15):1565-1574
ABSTRACTThis work was focused in to develop an electroanalytical method based on a direct modification of a glassy carbon electrode (GCE) by the deposition of successive aliquots of diluted dispersions of functionalised carbon nanotubes (MWCNT-COOH) in ethanol (0.1 mg.mL?1) aiming the determination of Diuron into seawater samples, a common antifouling substance, using differential pulse voltammetry as electroanalytical technique. The GCE/MWCNT-COOH showed a sensitivity of 2.20 μA/μmol L?1 about 10 times higher than the unmodified counterpart (GCE) which showed a sensitivity of 0.192 μA/μmol L?1. The limits of detection and quantificationwere 6.88 × 10?8 and 2.29 × 10?7 mol L?1 for GCE/MWCNT-COOH while for GCE were 7.87 × 10?7 and 2.62 × 10?6 mol L?1, respectively. The applicability was evaluated with spiked detectable amounts of Diuron into seawater samples. The recovery results were between 76% and 119%. 相似文献
53.
Yuling Wang Rong Jin Neso Sojic Dechen Jiang Hong‐Yuan Chen 《Angewandte Chemie (International ed. in English)》2020,59(26):10416-10420
The inside walls of a nanopipette tip are decorated by a Pt deposit that is used as an open bipolar electrochemiluminescence (ECL) device to achieve intracellular wireless electroanalysis. The synergetic actions of nanopipette and of bipolar ECL lead to the spatial confinement of the voltage drop at the level of the Pt deposit, which generates ECL emission from luminol. The porous structure of Pt deposit permits the electrochemical transport of intracellular molecules into the nanopipette that is coupled with enzymatic reactions. Thus, the intracellular concentrations of hydrogen peroxide or glucose are measured in vivo as well as the intracellular sphingomyelinase activity. In comparison with the classic bipolar ECL, the remarkably low potential applied in our approach is restricted inside the nanopipette and it minimizes the potential bias of the voltage on the cellular activity. Accordingly, this wireless ECL approach provides a new direction for analysis of single living cells. 相似文献
54.
An electrochemical method was developed for the sensitive determination of chlorogenic acid using a boron doped diamond electrode (BDDE) modified with nano‐carbon black (nano‐CB). The active surface areas were found to be 0.059 and 0.146 cm2 for the unmodified BDDE, and nano‐CB/BDDE, respectively. Compared with a BDDE, the nano‐CB/BDDE exhibited a well‐defined redox couple for chlorogenic acid. In addition, the plot of the peak current response changing from a square root to a linear dependence on scan rate is attributed to the transition from planar diffusion to surface behaviour. The anodic and cathodic peak separations (ΔEp) were 97 mV and 14 mV at BDDE and nano‐CB/BDDE, respectively. The decrease in ΔEp at the proposed electrode indicated that the process of chlorogenic acid was greatly accelerated. Square wave voltammetry (SWV) exhibited a dynamic range in which the current versus the concentration of chlorogenic acid were linear from 2.0×10?8 to 2.0×10?6 M with a LOD of 4.1×10?9 M (based on 3Sb/m). The nano‐CB modified BDDE provided improved electrochemical behavior, high electrocatalytic activity, high sensitivity and good reproducibility. 相似文献
55.
56.
将卷积技术应用于循环示波计时电位信号的处理,提出了2.5次微分循环示波计时电位法并将其用于对铑在HCl-KBr底液中的示波性质的研究。实验结果表明:在HCl+KBr体系的示波图上,Rh^3+的特殊峰是由于铑 对氢的催化作用而产生的;在Y^2.5-E曲线上峰高与Rh^3+浓度在4×10^-7-7×10^-5mol/L范围内呈线性关系,检测下限为8×10^-5mol/L。 相似文献
57.
Gold nanoelectrodes ensembles (NEEs) have been prepared by electroless plating of Au nanoelectrode elements within the pores of a microporous polycarbonate template membrane. Cyclic voltammograms recorded in (ferrocenylmethyl) trimethylammonium hexafluorophosphate (FA+ PF6−) solutions showed that these NEEs operate in the “total-overlap” response regime, giving well resolved peak shaped voltammograms. Experimental results show that the faradaic/background currents ratios at the NEE are independent on the total geometric area of the ensemble, so that NEE can be enlarged or miniaturized at pleasure without influencing the very favorable signal/noise ratio. Differential pulse voltammetry (DPV) at the NEE is optimized for direct determinations at trace levels. DPV at NEE allowed the determination (with no preconcentration) of trace amounts of FA+, with a detection limit of 0.02 μM. The use of NEE and DPV in cytochrome c (cyt c) solutions showed the possibility to observe the direct electrochemistry of submicromolar concentration of the protein, even without the need of adding any promoter or mediator. 相似文献
58.
制备了十六烷基三甲基溴化铵/正丁醇/正庚烷/水四组分体系的相图。讨论了 体系中助表面活性剂与表面活性剂的质量比k_m对形成微乳状液单相区域大小的影 响。以二茂铁为电活性探针用半微分电分析法测定系列微乳样品的表观扩散系数 D_(app),从表观扩散系数D_(app)随含水量Φ_w的变化确定微乳液的微结构和结构 转变。电导率数据证实了半微分电分析的实验结果。 相似文献
59.
Mariana Bartilotti Maísa Azevedo Beluomini Maria Valnice Boldrin Zanoni 《Electroanalysis》2021,33(5):1346-1355
A molecularly imprinted polymer (MIP) sensor was successfully constructed on glassy carbon electrode for the determination of 1-naphthol (1-Nph). The sensor was constructed by electropolymerization on bare GCE in the presence of the target molecule. The recognition of 1-Nph was conducted indirectly using [Fe(CN)6]3−/4− as redox probe. The MIP sensor presented wide linear working range and limit of detection of 1.5×10−9 mol L−1. The MIP sensor was applied for the determination of 1-Nph in oilfield produced water. The results obtained showed good selectivity and sensitivity of the proposed sensor in terms of 1-Nph quantification. 相似文献
60.
The study of a new type of working electrode - the renovated silver ring electrode (RSRE) - for lead ions detection via differential pulse anodic stripping voltammetry (DP ASV) without removal of oxygen is reported. The only four constituents of the RSRE: a specially constructed silver ring electrode, a silver sheet used as silver counter/quasi-reference electrode and a silicon O-ring, are fastened together in a polypropylene body. The renovation of this electrode is carried out through mechanical removal of solid contaminants and electrochemical activation in the electrolyte which fills the RSRE body. Excellent repeatability and reproducibility - also in organic samples solutions - were reached in a period of a few weeks through the renovation of the electrode surface before each measurement. The reduction and stripping of lead on silver electrode under the DP ASV conditions are underpotential deposition/dissolution phenomena. The RSRE is used for the determination of Pb ions in concentrations ranging from 1 × 10−9 to 1 × 10−7 M. The repeatability of DP ASV runs in synthetic solutions covering the entire concentration range is better than 2%. Obtained calibration curves are represented by a correlation coefficient of at least 0.999. The detection limit (LOD) for the time of electrodeposition equal to 60 s is 0.2 × 10−9 M. LOD for Pb2+ detection at the RSRE is similar to this reported for a rotating silver electrode in subtractive anodic stripping voltammetry (E. Kirowa-Eisner, et al., Anal. Chim. Acta, 385 (1999) 325). The analysis of Pb2+ in synthetic solutions with and without surfactants, certified reference materials and natural water samples have been performed. 相似文献