线性变位极谱法研究(ⅩⅤ)——铜(Ⅱ)-L-肾上腺素配位吸附波

本文提出了Cu(Ⅱ)-L-肾上腺素的极谱配位吸附波,在pH为6.9的B.R.缓冲溶液中.该波的峰电位为-0.246V(vs.SCE).对极谱波电流、电位性质和电极反应机理进行了研究,测定了电极反应速率常数(k_s)、转移系数(α)、配合物的组成及其表观稳定常数和化学反应速率常数。     

催化波在矿物原料分析中的应用——催化法极谱测定矿石中微量钒

本文提出微量的五价钒在苦杏仁酸-氯酸钾的微酸性介质中产生灵敏度为0.001微克/毫升的催化极谱波,半波电位为-0.965伏(对饱和甘汞电极)。从溶液酸度、底液组份、汞柱高度、温度等因素对波高的影响以及从极谱波的对数分析确定:由五价钒产生的极谱波系由它催化生成的苯甲醛在电极上进行单电子扩散还原的可逆波,不具有动力波特性。讨论并通过实验证实产生催化扩散电流的电极过程和反应机理。拟定了无须经过分离和富集手续测定矿石中0.000x—0.5％的五氧化二钒的快速简便操作流程。     

阳极溶出催化极谱法测定微量碲

使用经典极谱法测定碲的灵敏度往往不能令人满意,后来出现了溶出伏安法和极谱催化波都提高了灵敏度。至于把二者结合起来应用于碲的测定尚未见报导。本法是把碲电解富集在工作电极上,然后在选定的催化体系中溶出,使其产生溶出催化波,从而提高了灵敏度。     

稀土元素的电分析化学研究——偶氮硝羧(CNA)作为稀土络合剂的极谱研究

本文应用多种极谱技术详细研究了CNA的极谱性质,求得了它的电极反应电子数、扩散系数和电极反应标准速率常数,提出了电极还原步骤,证明了波的歧化反应机理。     

钒极谱催化波的研究 Ⅰ.钒-磷酸盐体系中过氧化氢极谱催化波的研究

本文对钒(Ⅴ)在磷酸盐体系中过氧化氢的极谱催化波进行了研究。确定了催化波的分析条件为0.2MNaH_2PO_4,0.05MH_2O_2,pH=5底液中,钒(Ⅴ)浓度由1×10~(-8)—7×10~(-7)M之间与电流呈直线关系。推导了利用催化电流求电极活性络合物组成的关系式为,1/i=1/imax 1/βimax·1/[H_PO_4~-]~(n■)并求得电极活性络合物组成为H_2VO_5H_2PO_4~(2-),相应条件稳定常数β=25.2。同时求得在砷酸盐底液中电极活性络合物组成为H_2VO_5H_2AsO_4~(2-),相应β=28.3。另外由汞柱高对催化电流影响、电毛细管曲线、i-t曲线、三角波扫描图形等实验判断.认为催化电流是由VO_3·H_2PO_4~(2-)在电极上被吸附,因而催化了过氧化络合物的形成和在电极上放电。     

方波极谱的原理及其技术

一、引言方波极谱的特点是有效地消除了一般极谱电容电流对还原电流测量的干扰,这方法是Barker在研究汞表面上的快速电极反应机构时发现的,对提高极谱测定的灵敏度和分辨能力有一定贡献。方波极谱能够测定可逆反应离子的浓度低至4×10~(-8)克分子/升,在大量前方放电物质同时存在时(甚至50,000比1)痕量物质仍能测定。方波极谱还可测定扩散系数、电极反应电子数和反应速度常数等。由于近年超纯分析的发展,方波极谱法得到了多方面的应用而日益受到重视。     

极谱催化波

利用催化波的极谱分析,其灵敏度特别高。一般极谱分析可测至10~(-4)M 的浓度,若用催化波可提高二、三个至四、五个数量级。但到目前为止,催化波的机理不很清楚,因而在分析中的应用也不多。1943年以来捷克斯洛伐克学派系统地研究极谱动力波,给催化波中的一种类型提供了理论的根据。我们试就文献所载,初步把催化波分为三类:氢催化波,化学反应与电极反应平行的催化波,和其他催化波,并通过具体例子加以说明,也许对扩大催化波在极谱分析中的应用和深入研究其机理有些用处。     

在碘酸钾存在下铝与茜素S的络合吸附波研究

在pH7.6的三乙醇胺缓冲溶液中,铝-茜素S络合物于-0.90V可产生一个灵敏的极谱波,加入碘酸钾后,极谱波负移至-0.94V,波高迅速增大,灵敏度增大约30倍。导数波高与Al^3 浓度在0.06-～10μg/L范围内呈线性关系,检测限达0.02μg/L。研究了极谱波性质及电极反应机理,证明极谱波为络合吸附催化波,在电极上还原的是络合剂茜素S,电还原的中是产物又被氧化回原状态而形成催化循环,使波高增大。利用本法直接测定了天然水中痕量铝。     

锗-连苯三酚-过氧化氢体系的催化极谱性质的研究

过氧化氢能被一系列物质在电极上的还原产物所催化分解。我们发现锗(Ⅳ)与邻苯二酚或连苯三酚的络合物对过氧化氢也有催化分解作用。当溶液中有过氧化氢存在时,能使上述络合物的极谱波增高(图1),并在一定浓度范围内,随过氧化氢浓度的增大而线性地增高。可应用此催化波于测定样品中的锗、微量氧或过氧化氢。本文研究锗-连苯三酚-过氧化氢体系的催化极谱性质。在883型极谱仪上应用此催化波测定锗的灵敏度为0.2微克/毫升。     

胱氨酸在铜(Ⅱ)-乙二胺溶液中的极谱配合物吸附波

本文研究了胱氨酸在铜(II)-乙二胶溶液中的极谱行为,发现了某些新的灵敏度较高的极谱波。该极谱波可应用于微量胱氨酸及半胱氨酸总量的测定。用多种方法研究了极谱波的性质。实验结果证明,这些极谱波的产生与铜和胱氨酸或半胱氨酸配合物在电极上的吸附有关。     

A polarographic investigation of the alkaloids of Ungernia

Summary In the investigation of the polarographic behavior of nine ungerine alkaloids, it was found that the reduction of narwedine forms the corresponding carbinol, while the reduction of hippeastrine, ungerine, and unsevine forms the corresponding tetrahydro derivatives. The catalytic hydrogen waves that all the ungerine alkaloids form can be used for analytical purposes.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 365–367, May–June, 1976.     

Polarographic analysis of the reduction waves of Pt(II)-SATSC complex

A polarographic study of the Pt(II)-salicylaldehyde thiosemicarbazone complex in sodium perchlorate as supporting electrolyte is described. In addition to the reduction wave of the complex, a catalytic hydrogen wave is also recorded. The characteristics of this catalytic hydrogen wave are studied under different experimental conditions such as varying acid/complex/supporting electrolyte/surfactant concentrations and also with mercury droptime. Based on these, a probable mechanism for the electrode process has been postulated. Presented at the 12th Annual Symposium in Chemistry held at the Indian Institute of Technology, Madras in March 1987.     

A contribution to the theory of D.C. polarographic current-voltage curves: Electrode reactions with three parallel charge transfer processes

Equations of polarographic current-voltage curves are derived for electrode reactions with three parallel charge transfer processes coupled by two chemical reactions on the basis of the staeady-state assumption in the reaction layer. If the rate constants of the charge transfer processes are sufficiently different from one another, the current-voltage curve consists of three separated waves and the equation for each wave has the same form as for a simple electrode reaction with one pathway.     

依来铬蓝黑B-镁配合物的极谱研究

依来铬蓝黑B是一种金属指示剂^[1],在pH1.95～12.20的Britton-Robinson缓冲溶液中产生一良好的还原波^[2]。在氨性缓冲溶液中,当溶液的pH在9.5～11.3时,依来铬蓝黑B也产生一明晰波。     

Polarographic investigations of some copper chelates of 3-arylazopentane-2,4-diones

The polarographic curves of the copper chelates of twelve substituted 3-arylazopentane-2, 4-diones exhibit single 4e diffusion-controlled irreversible waves between pH 2 and 11. The two azo groups in the compound are equivalent so that only a single 4e wave is obtained; no copper reduction wave is observed. The polarographic behaviour differs from that of p-bisazobenzene. There is a linear correlation between the E$\text{1}\text{2}$ values and the Hammett substituent constants.     

Polarographic Studies on Se(IV) in Absence and Presence of Pb(II), Zn(II) and Sb(III) Ions in Aqueous N-(2-ACETAMIDO) Imino Diacetate Buffer Solutions

Abstract

The polarographic reduction and determination of selenite ions in absence and presence of a mixture of some cationic species such as, Pb(II), Zn(II) and Sb(III) in N-(2-acetamido) imino diacetate solutions, at constants of ionic strength 0.1 mol dm^?3 (KNO₃) and temperature 25°C was studied using direct current and differential pulse polarographic (DPP) techniques. It was shown that reduction of Se(IV) takes place along one, two or three waves depending on the pH value of the solution using the direct current polarographic measurements. The reduction of Se(IV) in N-(2-acetamido) imino diacetate buffer solutions was found to be reversible and involving six electron transfer process. Microcoulometric experiments was performed at the limiting current region of the different waves and at various pH values. Kinetic parameters and wave characteristics for the reduction of selenite ions have been calculated. A method for the analytical determination of selenite ions in either simple or quadruple mixture of ADA buffer solutions using DPP techniques are reported and discussed.     

Differential-pulse polarography of amino acids in acetaldehyde-borax medium

A differential-pulse polarographic method for the determination of amino acids is reported, based on the formation of Schiff's base compounds in borax buffer solution (pH 10.10) containing acetaldehyde. The compounds are reduced at a mercury electrode with peak potentials of about ?1.5 V (vs. SCE) and well defined polarographic waves are obtained which can be used to determine amino acids in borax medium. The differential-pulse polarographic method was found to be the most sensitive and suitable for the determination of amino acids in the concentration range 1 × 10^?6–8 × 10^?4 M (lysine) and 2.8 × 10^?6–1 × 10^?3 M (arginine). The polarographic characteristics of these waves were studied by differential-pulse polarographic and cyclic voltammetric methods. The waves are ascribed to the reduction of the imido group in the Schiff's base compounds. The procedure was applied to the determination of lysine and arginine in foodstuffs and the total proteins in serum samples.     

Application of the modified polarographic Brdička method for cancer testing

This paper reviews the application of a modification of the polarographic Brdi?ka method for cancer testing. The modification comprises the catalytic electroreduction of metal ions (here called Brdi?ka method based on catalytic metal ion reduction for cancer testing—BMMCT) and/or the electrooxidation of proteins, instead of the classical approach based on the catalytic electroreduction of protons, i.e., hydrogen waves (here called Brdi?ka method based on catalytic hydrogen evolution for cancer testing—BMHCT). Further, in the modified method, the mercury electrode has been replaced by a nontoxic solid electrode and the entire measuring system has been automated. The modified method excels in improved testing rates and sensitivity of cancer testing. The cancer testing of vaginal secretions is characterized by high specificity as well.     

Logarithmic analysis of two overlapping d.c. polarographic waves: V. Application of a minicomputer to automatic analysis

A system for automatic analysis of d.c. polarographic waves, based on a DEC PDP-11/20 minicomputer and a PAR 170 Electrochemical system is described. More general expressions for analysis and separation of overlapping d.c. polarographic waves are derived than those previously reported in the literature. Corresponding programs are prepared in order to enable the automatic interpretation of polarographic experiments in an on-line system.     

Die Tropfzeitabhängigkeit der polarographischen Halbstufen-potentiale von 2-Phenylchinoxalin

Reversible redox reactions which are followed by irreversible steps give often polarographic waves with drop life dependent shapes. A mathematical model is proposed which is capable to describe the change of the polarographic waves of quinoxalines, even at short drop lives and slow reactions of the irreversible step.