Sequential potentiometric complexometric redox determination of iron(III) and cobalt(II) with application to alloys

A simple potentiometric method is presented for successive determination of iron(III) and cobalt(II) by complexometric titration of the iron(III) with EDTA at pH 2 and 40 degrees , followed by redox titration of the cobalt(II) complex with 1,10-phenanthroline or 2,2'-bipyridyl at pH 4-5 and 40 degrees , with gold(III). There is no interference in either determination from common metal ions other than copper(II), which severely affects the cobalt determination but can be removed by electrolysis. The method has been successfully applied to determination of iron and cobalt in Kovar and Alnico magnet alloys.     

Potentiometric redox determination of gold(III) and its application to alloys

The simple potentiometric method proposed for the indirect determination of 1–10 mg of gold(III) is based on reduction to the metal with excess of cobalt(II) in the presence of 1,10-phenanthroline or 2,2'-bipyridine at pH 3 and 50°C, and titration of the unused cobalt(II) complex with iron(III) chloride solution. Many metal ions can be tolerated; Ag(I) and Pd(II) are eliminated by precipitation with sodium chloride and 1,10-phenanthroline or 2,2'-bipyridine, respectively, but Hg(II), Fe(III) and Pt(IV) interfere. The method is applied to the determination of gold in alloys.     

Semiautomatic and automatic catalytic amperometric and catalytic constant-current potentiometric titrations of gold(III)

Semiautomatic and automatic amperometry and constant-current potentiometry were used to follow the course of catalytic titration of gold(III) with potassium iodide. The Ce(IV)-As(III) system in the presence of sulfuric acid was used as the indicator reaction. The possibilities of the application of two types of graphite electrodes were investigated. The effect of concentration of the indicator reaction components, and the presence of organic solvents and acids on the shape of the catalytic titration curves was studied. Amounts of 80–900 μg of gold(III) were determined with a relative standard deviation less than 1.1%. The results obtained are in good agreement with those of comparable methods.     

Coulometric titration of gold with electrogenerated chloro-cuprous ion

A method for the coulometric titration of +3 gold to the metallic state with clectrolytically generated chloro cuprous ion is described Quantities of gold from as little as I mg to 100 mg or more were titrated in a volume of 100 ml with an average error of ± 0.3%.The titration is applicable to the determination of gold in the presence of large amounts of copper, silver, mercury, lead, and most of the elements with which gold commonly is associated. Small amounts of +4 platinium (less than half the amount of gold) are innocuous, but larger quantities of platinum produce a large positive error     

Liquid anion exchanger study of gold (III) from aqueous halide media with N-n-octylaniline

N-n-octylaniline in xylene is used for the extractive separation of gold(III) from halide media. Gold(III) was extracted quantitatively with 10 ml of 2% reagent in xylene from 0.5-10 M and 0.5-8 M hydrochloric acid and hydrobromic acid, respectively. It was stripped from the organic phase with ammonia buffer solution (pH 10.1) and estimated spectrophotometrically with stannous chloride. The effect of metal ion, acids, reagent concentration and of various foreign ions has been investigated. Method is applicable to the analysis of synthetic mixtures containing platinum metals and alloy samples. The method is fast, accurate and precise.     

Coulometric titration of penicillins and penicillamine with mercury(II)

An absolute coulometric method based on the titration of hydrolysed penicillins with coulometrically generated mercury(II) is presented. An amalgamated gold plate is used as anode and the titration is performed in a pH 4.6 acetate buffer solution. The method gives values which deviate by less than 1% from values obtained by other absolute methods. The relative standard deviation for determination of penicillin G is 0.4%. The determinations of penicillamine and mixtures of penicillamine and penicilloate are also reported.     

示波极谱—铜试剂法测定巴比妥类药物的含量

采用示波极谱－ＤＤＴＣ（二乙基二硫代氨基甲酸钠，铜试剂）滴定法测定巴比妥类药物及其制剂的含量。该法到目前为止未见报道，它具有快速、准确、终点直观的特点，溶液的颜色、产生的沉淀、制剂中的赋形剂对滴定无影响，所测结果与药典法无显著差异。     

Potentiometric titration of gold in ores with potassium iodide

Summary A direct potentiometric titration method for the determination of gold in ores and alloys is described. It is based on the reduction of Au(III) with iodide ions yielding accurate and reproducible results. Detection limit and sensitivity were 0.06 and 0.032 mg/l Au, respectively. The linear response range was between 0.1 and 120 mg/l Au. The method can be used for the routine assay of gold in different kind of samples.     

电位滴定法测定火试金得到的金银合粒中的银

本文研究了用自动电位滴定仪测定外购铜物料样品中经火试金熔炼、富集、灰吹后得到的金银合粒中银的方法。金银合粒用硝酸溶解后在自动电位滴定仪上用硫氰酸钾标准溶液滴定银量,选择了仪器的测定条件,考察了溶液酸度、共存元素对测定的干扰。方法相对标准偏差为1.34％～3.62％,测定结果与硫氰酸钾手工滴定法和减杂法相一致。方法的准确度和精密度均能满足分析需要,具有较强的实用性和推广价值。     

Precise and accurate determination of halogens in organic compounds using an amalgamated gold electrode

Precise and accurate titration of halogens in organic and inorganic materials has been studied. The halogen was titrated with coulometrically generated silver and determined potentiometrically by using an amalgamated gold indicator electrode. An argentometric titration curve using the amalgamated gold indicator electrode showed a large jump in potential at the endpoint as well as in mercurometric determination. Sodium carboxymethyl cellulose (CMC) and aluminum nitrate were added as they are most effective for clarifying the sample solution and eliminating adsorption of the halide ion on the silver halide generated. The electrolytes used were 0.5 M nitric acid containing 0.1% CMC and 0.2 M aluminum nitrate. Approximately 0.2 mmol of chloride, bromide, and iodide ions were titrated with high precision and accuracy. Their standard deviations were 0.03, 0.02, and 0.02%, respectively, with no apparent systematic error. The precise determination of halogens, employing oxygen flask combustion and dissolution of the halide salts in the electrolyte, was carried out with ±0.1% absolute error using samples weighing between 20 and 30 mg.     

The analysis of slag for copper,total iron,iron(II) and iron(III) by titration,controlled potential coulometry and electrodeposition

The interference of copper in the titrimetric determination of iron(II), iron-(III) and total iron in slags is discussed. The titration of iron(II) suggested by Bowen and Schairer is accurate and can be conducted with a reproducibility of ±0.29% at the 95% confidence level. Electrolytic copper-iron separation techniques were adapted to copper-containing iron-silicate slag, to obtain a reliable method for copper and total iron analysis. The theoretical and practical limitations for performing potentiostatic determinations of iron(III) in copper-containing slag are reviewed. Some determinatons were made but initial results were unreliable. Complete analyses of copper-gold alloys were made potentiostatically. Copper plus gold recoveries were ca. 99.8%.     

A precise direct heterometric determination of traces of copper with diethyldithiocarbamate in excesses of metals

The most favorable conditions for the heterometric titration of copper with sodium diethyldithiocarbamate and the influence of complexing agents on the titration were investigated.Titrations of copper were carried out in the presence of large excesses (? 99. 5%) of most of the common cations. A method is presented for a precise determination of traces of copper in metals and salts.The titration time was 7–10 minutes. In most titrations the amount of copper present was determined with an error close to zero.     

Volumetric determination of primary arylamines and nitrites, using an internal indicator system

A new nitrite titration method is presented. The titration is performed in the presence of a standard solution of 4,4'-sulphonyl-dianiline and diphenylamine, which is used as an internal indicator. An intense red colour develops during the titration as a result of a simultaneous diazotization and coupling process. A very sharp end-point is given by a colour change to yellow. The titration is performed at a temperature of about 45 degrees in the presence of large amounts of nitrate. The method is specific and precise. It is suitable for the direct volumetric determination of various easily diazotized primary arylamines, sulphonamides and other amino-compounds which can be determined by nitrite titration. It is suitable also for the indirect determination of nitrites. The method is applicable on the semimicro and macro scales.     

盐酸黄连素示波电位滴定法的研究

黄连素(小檗碱)是一种重要的抗菌素药,用于治疗细菌性痢疾和一般炎症。现行的分析方法为碘量法,比较烦琐。本文将示波电位滴定法中的金属片电极涂上一层含活性物质的PVC膜,使电极对黄连素等有机药物产生一定的响应,可用于四苯硼酸钠直接滴定黄连素的终点指示。该方法比药典法、直接电位法更简便、直观,易推广使用,同时也扩大了示波电位滴定法的应用范围。     

Accurate and precise determination of 2–25 mg amounts of uranium by means of a special automatic potentiometric titration

Analytical and Bioanalytical Chemistry - A precise and accurate potentiometric titration of 2–25 mg of uranium is described. The uranium is reduced to U(IV) according to the method of Eberle...     

Improved method for the constant-current potentiometric determination of plutonium

A highly precise method is described for the determination of plutonium by constant-current potentiometric titration with primary standard potassium dichromate. The relative standard deviation is 0.04% or better.     

全自动电位滴定法测定锂电池原料碳酸锂中主成分的含量

采用全自动电位滴定法测定锂电池原料碳酸锂中主成分的含量,用盐酸标准溶液进行滴定,考虑自动电位滴定仪的灵敏性和准确度,通过多次对比实验,确定了仪器的最佳工作参数、滴定剂浓度和样品称样量等滴定条件;对两个不同品位试样分别进行了11次平行测定,相对标准偏差(RSD)均小于1％.在碳酸锂试样中加入基准物质无水碳酸钠进行碳酸根的...     

Accuracy in the precise coulometric titration of ammonia and ammonium ion with electrogenerated hypobromite

A precise and accurate method in which ammonia and ammonium ions are coulometrically titrated with electrogenerated hypobromite was studied. Through the measurement of the current efficiency for generating hypobromite and the dependencies of titration results on electrolysis current and delay time between sampling and starting electrolysis, precision and accuracy of 0.01 and 0.02%, respectively, were obtained. The accuracy of the titration was compared with that of acidimetric coulometric titration of ammonia.     

Volumetric determination of iron (III) with hydroxylamine as a reducing agent

Summary A new volumetric method has now been developed for the determination of iron(III) through reduction to iron(II) with excess of hydroxylamine. The reduction is completed at the temperature of the boiling water bath in 10 min, keeping the acidity at 0.2–0.5 N sulphuric acid. The mixture is cooled and treated with enough 1 1 sulphuric acid to bring up the acidity to 6 N. It is then titrated with a standard solution of sodium vanadate, using N-phenyl anthranilic acid as inside indicator. Diphenyl benzidine, barium diphenyl sulphonate, or 1,10-phenanthroline cannot be used as indicators in this titration, because of the interference of the unreacted hydroxylamine.The method has been found to be very precise, and convenient. It has also the advantage that it is subject to fewer interferences than the existing methods.One of us, Mrs. G. Somidevamma, desires to thank the Ministry of Education Government of India for the award of Research Fellowship which enabled her to take part in this investigation.     

Conductometric titration of pindolol and propranolol using ammonium reineckate and potassium tetracyanonickelate

A simple and sensitive conductometric method for the determination of 2–24 mg of pindolol and propranolol hydrochlorides using ammonium reineckate and potassium tetracyanonickelate in an ethanol-water mixture is described. The effect of the solvent ratio, reagent concentration, time and temperature on the shape of the titration curve is studied. Statistical treatment of the experimental results indicates that the method is precise and accurate. The accuracy of the method is indicated by the excellent recovery (98.2–101.2%) and the precision is supported by the low standard deviation value < 0.10. The sensitivity of the proposed method is discussed and the results are compared with the pharmacopoeial non-aqueous titration method.