交流示波极谱滴定法

用交流示波极谱曲线(dE/dt)=f(E)上切口的出现或消失来指示滴定终点的容量分析方法称为交流示波极谱滴定法,简称示波极谱滴定。     

交流示波极谱滴定汞的研究

1 引言 用交流示波极谱滴定仪指示滴定终点的交流示波极谱滴定法已得到广泛的应用。在pH6的HAc-NaAc缓冲溶液中并有Br~-存在时,Hg~(2+)在金电极上有灵敏的切口,可用于指示滴定终点。本文对EDTA滴定Hg~(2+)的条件进行了研究。所拟定的方法简便、快速、准确,终点清晰、直观、敏锐、不受颜色、沉淀的影响,并已用于岩     

锆英石单矿物中锆的交流示波极谱滴定

交流示波极谱滴定法作为一个以交流示波极谱曲线图形的变化来判断终点的方法已应用于许多元素的测定。本文根据pH5-6时铅在示波极谱图上有敏锐的切口,试验了一个间接测定高含量锆的方法,即加入过量EDTA络合锆,用铅反滴定至出现铅之切口为终点。干扰元素用钛铁试剂和丙二酸掩蔽。方法简单、快速、准确,不经任何分离手续。由于过量EDTA存在避免了锆盐的水解,可在常温下滴定,掩蔽剂与干扰离子形成的有色络合物由于终点直观不影响测定,优于文献采用的方法。本法可应用于锆英石单矿物的分析。     

电流反馈示波极谱滴定法

本文提出了电流反馈示波极谱滴定法的原理、仪器装置及操作技术。为了提高去极剂切口的灵敏度, 可将dE/dt信号转换为电流信号后再反馈回电解池以补偿充电电流,一般可将切口灵敏度提高1至5倍, 图形分辨率也较经典方法高, 从而使滴定终点的变化更为敏锐, 扩大了示波极谱滴定的应用范围, 推导了电流反馈的交流电流极化理论公式, 分析了电流反馈对示波极谱图形、去极剂切口灵敏度及切口电位的影响。     

交流示波极谱滴定法测定铈

利用Ｃｕ（Ⅱ在交流示波极谱曲线上有敏锐的切口并可指示交流示波极谱滴定终点的性质，提出用ＥＤＴＡ络合Ｃｅ（Ⅳ），并用Ｃｕ（Ⅱ）标准溶液回滴剩余的ＥＤＴＡ从而测定铈的方法。结果表明，该法简便、快速、干扰较少。     

影响示波极谱中和滴定终点示波圈变化的因素 Ⅰ.交流电流密度

指示示波极谱滴定终点的方法有:示波极谱图形的位移,图形的扩张或收缩以及切口的出现与消失等。它们与通过电解池的交流电流的大小和电极面积密切相关。 (一)示波极谱滴定终点示波图的变化与电流密度的关系当通过电解池的交流电流很小时,即指示电极上没有任何电极反应而仅为充电电流时,“E-t”曲线可用下式表示:     

交流示波极谱图重现性的研究

本文用集成运放为主要元件改进了交流示波极谱的实验线路,并用该线路在严格控制实验条件的情况下,对交流示波极谱图的重现性进行了系统的研究。实验表明,交流示波极谱图的重现性良好,可将其用于有机化合物及有机药物的定性鉴定。     

熔融盐中应用交流示波极谱分析有机物的研究

本文研究了在熔融的甲酸铵介质中,温度为125℃±0.5℃时应用交流示波极谱研究硝基苯等有机化合物的示波极谱特性.并且发现和采用流汞电极在1M 氢氧化钠溶液中所获得的电容切口是一样的简单.同时还发现随着电解纯化甲酸铵时间的增加.同量硝基苯产生的切口有明显地加深.提高了灵敏度.本文还使用滴汞电极、悬汞电极和 Kaliskova 电极对硝基苯进行了定性和定量.具有较高的灵敏度。重现性也较好.实验还指出.采用固体电极材料在交流示波极谱中的应用将是继续研究的新课题. ·     

光荣榜——《高等学校化学学报》刊发文章获奖题录(续)

(一)国家自然科学奖 (23)获奖项目:示波滴定(1991年,三等奖,南京大学) 1.示波滴定;毕树平,高鸿,1989,10(8):860 2.交流示波极谱研究(Ⅲ)——底液Micka公式的修正;毕树平,高鸿;1990,11(5):529 3.交流示波极谱研究(Ⅳ)——切口的性质;毕树平,高鸿;1990,11(6):579 4.交流示波极谱图的频谱分析;毕树平,祁洪,都思丹,高鸿;1991,12(5):604 5.Kalman滤波分辨交流示波极谱图中重迭切口;毕树平,都思丹,王忠,高鸿;1991,12(12):1592 (二)国家教委科学进步奖     

交流示波极谱法测定工业污水中的微量汞

本文提出了用交流示波极谱法测定工业废水中的微量汞。在pH=6的HAc-NaAc缓冲液中,有Br-存在时,Hg2 在金电极上有敏锐的切口,可用于指示终点。方法简便、快速、准确,终点清晰、直观,切口敏锐,不受颜色和沉淀的影响,用于废水中的微量汞的测定,结果满意。     

Complexation reaction of metal ions with peptide systems. Part II. Potentiometric studies of the complexes of glycyl-DL-valine with Gd, Dy, Er and Yb

The stable complexes of amino acids with rare earths have found importance in the separation of these metals¹. The complexation reactions of a number of dipeptides with copper and nickel have been reported in the literature^{2 – 9}; but little work appears to have been done with rare earth metals. This paper is a continuation of our earlier communication¹⁰, and deals with the study of complexes of Gd³⁺, Dy³⁺, Er ³⁺ and Yb³⁺ with Glycyl-DL-valine. The Calvin—Bjerrum^{11, 12} pH titration technique, as modified by Irving and Rossotti¹³, has been employed.     

Effects of copper on dielectric properties of E. coli cells

Dielectric properties of E. coli cells before and after Cu²⁺ incubation were investigated by using the dielectric spectroscopic technique. The dielectric spectra are analyzed theoretically by means of the extended three-shell ellipsoidal model, which can reflect the complicated morphological structure of E. coli cell including the outer membrane, the periplasmic space, the inner membrane and the cytoplasm. The results showed that dielectric properties of these cellular components were changed with Cu²⁺ treatment in a time- and concentration-dependent way. The permttivity of the outer membrane increased with the incubation time and concentration of Cu²⁺, possibly because polarizability of the outer leaflet of lipopolysaccharides was affected by Cu²⁺. The conductivity of the periplasmic space decreased with the incubation time and concentration of Cu²⁺, possibly due to the damage of peptidoglycan. The decreased permittivity of the inner membrane may be caused by disturbance of the lipid bilayer structure produced by Cu²⁺ incubation. The decreased cytoplasmic conductivity may be the consequence of the leakage of K⁺ from it. The cytoplasmic permittivity decreased with Cu²⁺ treatment probably because of the leakage of its some components.     

Chemiluminescence mapping. I. Experimental method and initial measurments on the D+F2 and F+D2 reactions

Measurements by a new experimental chemiluminescence method of the nascent DF product vibrational distribution confirm earlier findings for the F + D₂ → DF(ν?4) + D reaction. The distribution for D + F₂ → DF(ν?15) + F shows a larger fraction (≈ 78%) of the reaction exothermicity channeled into product vibration than is observed by conventional chemiluminescence measurements on the parallel H + F₂ system (58%). The new method, termed chemiluminescence mapping for its simultaneous recording of spectrally and temporally resolved chemiluminescence, differs from the earlier arrested relaxation and measured relaxation techniques by the introduction of a short duty cycle pulsed molecular reagent source, a modified deuterium dissociation source, and signal averaged (time resolved), detection of the DF infrared emission. The chemiluminescence mapping technique results for D + F₂ and F + D₂, are presented; apparent deviation from the energy distribution in the H + F₂ system is discussed.     

人工神经网络用于交流示波计时电位法的研究

提出了交流示波计时电位法的人工神经网络校正方法,并对其可行性和适用性进行了探讨,用此方法分别解析了大量Ｔｌ＾＋存在时Ｐｂ＾２＋和大量Ｉｎ＾２＋存在时Ｃｄ＾２＋的交流地波计时电位法的ｄＥ／ｄｔ－Ｅ曲线,结果表明,对Ｐｂ＾２＋和Ｃｄ＾２＋和Ｃｄ２＋的预测最大相对误差不超过５％,其性能良好。     

Chromo- and Fluoroionophores Based on Diaza-Crown Ethers for Alkaline Earth Metal Ions

Abstract

Two new metal-selective dyes were synthesized and used to develop methods for determining Ca²⁺ and Mg²⁺. A chromogenic diaza-18-crown-6 with an alizarin group at each crown nitrogen is a calcium-selective ionophore used for extraction-spectrophotometry. The detection limit for the technique is 1 × 10^?5 M Ca²⁺. Fluorometric determination of Mg²⁺ is performed using a diaza-15-crown-5 derivatized with two methyiumbelliferone groups. This method allows for the one-phase determination of Mg²⁺ down to 7 × 10^?6 M.     

Competing binding of metal ions with protein studied by microdialysis

A method has been established to study the competing binding of metal ions with protein by a combined technique of microdialysis with high performance liquid chromatography (HPLC). Ni2+, Cd2+, Zn2+, Cu2+ and human serum albumin (HSA) were chosen as model metal ions and protein. The experimental results show that Ni2+ and Cu2+ share a common primary binding site on HSA, and Zn2+ and Cd2+ share a different common primary binding site from them, but there is a common multi-metal binding site for all of those four metal ions. This method show advantages of fast sampling, easily to be operated and especially to be useful when ideal spectroscopic probes are not available for the study of interaction between protein and metal ions.     

Effect of light on calcium transport in bull sperm cells.

The effect of light on calcium transport was studied. Bull sperm cells were irradiated with an He-Ne (630 mm) laser and a 780 nm diode laser at various energy doses, and 45Ca2+ uptake was measured by the filtration technique. It was found that there is an accelerated Ca2+ transport in the irradiated cells, which means that laser light can stimulate Ca2+ exchange through the cell membrane. This may cause transient changes in the cytoplasmic Ca2+ concentration which, in spermatozoa, has a regulatory role in control of motility and acrosome reaction, and in other cells can trigger mitosis.     

Synthesis of new luminescent materials activated with divalent samarium

A simple technique for the preparation of powder compounds doped with divalent samarium is described. The reaction is carried out in nickel containers sealed in an inert atmosphere. The samarium impurity is introduced as samarium trifluoride SmF₃, and metallic samarium powder acts as the reducing agent to change Sm³⁺ into Sm²⁺. Using this method, samarium has been stabilized in the divalent state in various fluorides: KMgF₃, BaLiF₃, BaY₂F₈, and KY₃F₁₀. The resulting compounds show under ultraviolet or visible excitation an intense luminescence in the red region characteristic of Sm²⁺-doped materials. The emission and excitation spectra of these phosphors are presented and briefly discussed.     

Selective reagents for solvent extraction of metals—II. Bis-quinaldic acids

Bis-quinoline-2-carboxylic acids in which the quinoline rings were joined via ether linkages to the 8-position have been synthesized and tested for metal extraction. The reagents extracted Cu²⁺ and Zn²⁺ selectively in the presence of Fe²⁺ and Fe³⁺ from aqueous sulphate solution.     

Complexation of polyacrylates by Ca2+ ions. Time-resolved studies using attenuated total reflectance Fourier transform infrared dialysis spectroscopy

The attenuated total reflectance Fourier transform infrared dialysis technique is introduced for the time-resolved investigation of the binding processes of Ca2+ to polyacrylates dissolved in water. We observed transient formation of intermediates in water with various types of coordination of the carboxylate group to Ca2+ throughout the complexation steps. Time-resolved changes in the spectra were analyzed with principal component analysis, from which the spectral species were obtained as well as their formation kinetics. We propose a model for the mechanisms of Ca2+ coordination to polyacrylates. The polymer chain length plays an important role in Ca2+ binding.