库仑分析法中一个值得重视的概念

库仑分析法中一个值得重视的概念龚琦（广西大学化学化工学院南宁５３０００４）库仑分析法是以电量作为测量信号，根据法拉第定律所建立起来的定量分析方法。而能否获得准确的电量数据，直接影响到分析结果的准确度，因此，无论在教学还是在科研工作中，对这个问题应给予...     

一种新的库仑微水滴定仪的设计方法

在传统微库仑滴定仪原理的基础上，利用８７５１单片机和微机，采用对电解电流时间调制的方法以及测量精度为准则判断滴定终点，从而大大地提高了仪器的测量精度和重复性。     

非水库仑滴定法测定碳

1引言碳（碳酸盐）的测定曾做过广泛研究，其中，非水库仑滴定测碳因其滴定效率高，稳定性好被列入ＡＳＴＭＤ－５１３－８２；该方法推荐使用美国库仑公司的专利仪器及电解液，其关键技术是非水电解液。本文对该方法的电解液进行了组分选择及优化，建立起完整的测定装置，取得了较好的结果；可作为测定金属含碳量、水体中溶解无机碳的首选方法，广泛应用于冶金、环保等领域。2实验部分2．１仪器与试剂ＫＬＴ－１型库仑仪（江苏电分析仪器厂）；ＰＨＳ－２型酸度毫伏计（上海雷磁仪器厂）。试剂：二甲亚砜、乙醇胺、四乙墓滨化胺为分析纯；…     

库仑自动分析定值系统研究

阐述库仑分析方法的工作原理及应用状况.介绍库仑自动分析定值系统的研制过程,包括恒电流源的研制、恒电位库仑分析装置的建立、分析和控制软件的编制、分析方法的建立等.将该定值系统用于标准物质定值,满足定值要求.     

恒电流库仑滴定装置的自动化

介绍了恒电流库仑滴定装置的结构与原理,对电解电流的自动恒定以及利用计算机对库仑滴定过程进行自动控制做了探索。     

恒电流动态库仑法检测空气中偏二甲肼

偏二甲肼[(CH_3)_2NNH_2](UDMH)是液体火箭的主要推进剂,具有中等偏高毒性,极易挥发.空气中最大允许浓度为0.5ml/m~3.因此,研制检测空气中微量UDMH的装置.对于预防其中毒,具有十分重要的意义.空气中UDMH的测定方法主要有:固体吸附/分光光度法;固体吸附/气相色谱法.这两种方法均有测量范围大、下限低、测量准确等优点,但操作复杂、仪器条件要求高,且不能连续测定.本文采用库仑滴定法测定空气中的UDMH,依据法拉第电解定律,研究空气中UDMH与库仑池中电解液进行电化学反应,测量其在反应过程中产生的电流值,得到空气中UDMH浓度与响应电流的关系,从而求出UDMH气体的浓度.     

微库仑法测定硫注意事项

根据微库仑法测定硫的基本原理和仪器本身的特点，分析了微库仑法测定硫时，电流、磁场、温度、气体流量、滴定池、电解液等因素对测定结果的影响，探讨了影响机理，提出了应注意的事项。     

吸附方波伏库仑法研究：I.简单吸附体系

对简单吸附体系方法伏库仑法进行了理论推导和实验验证，讨论了各种因素对伏库仑曲线的影响，研究表明，对于简单吸附体系，方法伏库仑法的灵敏度和检测限均优于方波伏安法。     

吸附方波伏库仑法研究 Ⅰ简单吸附体系

对简单吸附体系方波伏库仑法进行了理论推导和实验验证，讨论了各种因素对伏库仑曲线的影响。研究表明，对于简单吸附体系，方波伏库仑法的灵敏度和检测限均优于方波伏安法。     

基准试剂纯度定值研究

本文介绍了基准试剂纯度定值装置的工作原理,研究制作了用于反映库仑滴定终点的终点指示器,并对基准试剂的纯度分析方法进行了研究,使定值精度达到了国内外先进水平。     

Coulometrie und das coulomb als universelle urtitersubstanz

The theoretical bases of coulometry are described as Well as the newly developed coulometric methods, such as the indirect coulometric method, coulometric iodometry, coulometric perman-ganatometry, and coulometric metallometry. Furthermore the application of coulometric methods to the determination and preparative separation of various isomers, to the study of chemical kinetics and for coulometric buffering is dicussed; the respective results obtained are presented and the potential further development is indicated.Based on the results mentioned, the possibility and usefulness is pointed out of the introduction in analytical chemistry of the electron or the coulomb, as a universal standard, instead of the -numerous cliemical substances, more or less suitable for this purpose, and the general use of the universal coulomb is proposed.     

Fast procedure for no-reference inversion-voltammetric determination of lead in aqueous solutions

Possibility of no-reference inversion-voltammetric determination of lead in aqueous solutions with the use of a preliminarily determined coulometric constant of the electrochemical cell, which enables substantially faster analysis as compared with the known analogs, was studied. The coulometric constants of electrochemical cells with a mercury film electrode were found for different solution volumes.     

Trace analysis for chlorinated hydrocarbons in air by quantitative combustion and coulometric chloride determination: application to standardization of vinyl chloride permeation tubes

Methods for high-temperature combustion of vinyl chloride in air were studied theoretically and two types of gas mixtures were found to give 100% conversion into HCl. The chloride was determined by coulometric titration with silver, in 70% acetic acid. Good agreement between theoretical and experimental results was obtained. Permeation rates of vinyl chloride from fluorinated ethylene propylene permeation tubes were determined gravimetrically and with the coulometric method developed. The standard deviations of the methods were 0.002 and 0.001 microg min respectively for permeation rates of 0.5 microg min when the temperature was controlled to +/- 0.02 degrees . The coulometric mean value was 99.9% of the gravimetric mean; 1 ppm of vinyl chloride in air could be determined coulometrically with a standard deviation of about 0.002 ppm.     

Coulometric Determination of the Antioxidant Capacity of Tea Extracts Using Electrogenerated Bromine

A coulometric procedure based on the reaction between aqueous extracts of tea with electrogenerated bromine compounds was proposed for the rapid estimation of the antioxidant capacity of different kinds of tea. The antioxidant properties of tea with respect to bromine are mainly due to naturally occurring flavonoids, tannins, and some vitamins. Photometric and coulometric data for black teas exhibit good correlation.     

Coulometric titrations with an ion exchange separation step

Summary The coupling is described of coulometric separation methods with an ion exchange separation step. Various methods of enrichment and separation are described using the analysis of nitrogen compounds, such as ammonia, urea and nitrite, as examples. A microcomputer controls the separation step and regulates the coulometric determination. Quantitative separations are achieved in all cases, so that the advantage of coulometric titration, as a precise absolute determination method, is retained.     

Coulometric titration of bases in acetic acid and acetonitrile media

The working conditions and the results for coulometric titration of milligram amounts of some bases in 0.1M sodium perchlorate in a mixture of acetic acid and acetic anhydride (1:6), are given. Determinations were made both by coulometric back-titration or direct titration at the platinum anode. Back-titration was done in the catholyte, by coulometric titration of the excess of added perchloric acid. The titration end-point was detected photometrically with Crystal Violet as indicator. The direct titration of bases was done at the platinum anode, in the same electrolyte, to which hydroquinone was added as anode depolarizer and as the source of hydrogen ions, Malachite Green being used as indicator. Similarly, bases can be determined in acetonitrile if sodium perchlorate, hydroquinone and Malachite Green are added to the solvent. Errors are below 1 %, and the precision is satisfactory.     

薄层分离-库仑滴定法测定茄尼醇

提出以２ｍｏｌ／ＬＫＢｒ－醋酸（１：３Ｖ／Ｖ）为电液,在阳极电生溴与尼醇发生反应来测定茄尼醇含量的库仑滴定法。茄尼醇与溴反应,其ｎ值为１８,对于烟叶以物中茄尼醇,以正己烷－二氯乙烷－丙醇为展开剂,用薄层色地邓以分离,用库仑滴定法进行测定 。     

Potentiometric and Coulometric Determination of Carbimazole

ABSTRACT

A method for the determination of carbimazole involving its reaction with iodine in an alkaline medium is presented. In volumetric titration with potentiometric end-point detection the range of determination is 30–500 μmol (5.6–93 mg). In coulometric titration using biamperometric end-point detection, 0.5–20 μmol (0.09–3.7 mg) of carbimazole was successfully determined. The coulometric titration was applied to the determination of carbimazole in tablets.     

Investigation on drying conditions and assays of amidosulfuric acid and sodium carbonate by acidimetric coulometric titration and gravimetric titration

Amidosulfuric acid and sodium carbonate as standards for acid–base titrimetry were assayed by coulometric titration and gravimetric titration. Amidosulfuric acid was directly assayed by coulometric titration with electrogenerated hydroxide ions, and sodium carbonate was assayed by gravimetric back-titration. For sodium carbonate, excess amount of sulfuric acid, whose concentration was determined by coulometric titration, was added to sodium carbonate, and then gravimetrically back-titrated using a sodium hydroxide solution whose concentration was determined by gravimetric titration using the sulfuric acid. The accuracy of the coulometric titration for amidosulfuric acid and sulfuric acid was evaluated by examining the current efficiency of pulse electrolysis, the amount of the electrolysis current used, and the time spent for a titration. In addition, the drying conditions for high purity primary standards have a significant effect on the titration results due to changes in the acid–base assay. The suitable drying conditions for amidosulfuric acid and sodium carbonate were evaluated by mass-change measurements, coulometric titration and gravimetric titration. The measurement uncertainties were estimated from the uncertainties on the titration processes. Finally, the assays of amidosulfuric acid and sodium carbonate were 99.986% ± 0.010% (k = 2) after drying at 50 °C for 2 h, and 99.970% ± 0.016% (k = 2) after drying at 280 °C for 4 h, respectively. In addition, the international consistency was confirmed by measuring certified reference materials (CRMs) available from different National Metrology Institutes, and the compatibility of values among CRMs was experimentally ascertained.