The polarographic determination of indium in zinc-base alloys : The determination of indium in mazak alloys

In this paper, the development of a co-precipitation method for the separation of indium from zinc alloys is described and a method for the determination of indium down to 0.5 p.p.m. in mazak alloys is presented. Results obtained in trials of this method are given and the final conclusions regarding this and previously developed methods are included.     

The polarographic determination of indium in zinc-base alloys : The determination of indium in zinc and in zinc alloys of low aluminium content

Studies of the application of an 8-hydroxyquinoline extraction and of a zinc oxide “collection” procedure for the separation of trace amounts of indium from zinc alloys are described and discussed. A combination of radio-chemical and polarographic determination were employed for this work. A polarographic method for the determination of indium in zinc and in zinc alloys of low aluminium content is presented     

The polarographic determination of aluminium in zinc-base die-casting alloys

A procedure for the direct polarographic determination of aluminium is described, with particular reference to zinc-base die-casting alloys. Interfering elements are removed by electrolysis of a solution of the alloy in a mercury-cathode cell. The solution is polarographed at a carefully controlled pH in a supporting electrolyte of magnesium chloride and sodium sulfate of appropriate concentration. The precision and accuracy of the method are shown to be satisfactory by the analysis of standard samples from three different laboratories.     

Extraction-photometric determination of indium in zinc-base alloys with bromopyrogallol red

The extraction-photometric determination of indium at the 5 p.p.m. level in highpurity zinc and zinc-base alloys is described. After a preliminary separation of indium by isopropyl ether extraction from hydrobromic acid medium, indium is determined by extraction into benzyl alcohol of its complex with bromopyrogallol red at pH 9.0. It is shown that 2:1, 1:1 and 1:2 complexes can be formed in aqueous and water-ethanol media; the 1:3 complex reported earlier was not found. The composition of the complexes extracted into benzyl alcohol from aqueous solutions at pH 6.5 and 9.0, was found to be 1:2.     

The application of the cathode ray polarograph to the analysis of explosives—III Simultaneous determination of nitroglycerine and dinitroglycol

A polarographic method for the determination of nitroglycerine and dinitroglycol in mixtures containing both of these substances is described. The nature of the reductions involved is discussed.     

The simultaneous determination of copper and iron in high purity aluminium using the k 1000 cathode ray polarograph

An accurate simultaneous determination of copper and iron in 99 99% aluminium can be carried out in 10–15 min, using the linear sweep polarograph. Lead can also be determined in the same solution The basic electrolyte used is sodium hydroxide and sucrose, but the addition of ethylene-diaminotetraacetic acid (EDTA) is necessary if manganese is present. The effect of EDTA on the reduction wave of copper and iron has been investigated     

The polarographic determination of lead in tin-base alloys

A polarographic method for the determination of lead in tin-base alloys is described For alloys containing more than 2% lead no separations are necessary; in those with a lower lead content, most of the copper present must be removed as cupric oxide Results are exact: ±4% of the amount of lead present.     

The polarographic determination of chromium in aluminum alloys

A convenient polarographic method for the determination of 0.1–0.5% of chromium in aluminum alloys is described. The alloy is dissolved in a bromine water-sodium hydroxide mixture; after suitable treatment, chromate is determined polarographically. Specific directions for the simultaneous running of a blank experiment are given ; this provision greatly improves the accuracy of the results obtained.     

The polarographic determination of aluminium* : General introduction polarography of solochrome violet r.s. in the presence of aluminium

A survay is made of the methods available for the determination of microgram quantities of aluminium, together with techniques for its separation from interfering ion species. The polarography of aluminium is briefly discussed and a. study is reported of a method involving the modification, by this element, of the polarographic characteristics of a diortho-hydroxy azo dye. Interferences other elements are given in detail and discussed. Means for their removal are suggested     

纳米纤维在辣椒粉中苏丹红Ⅱ测定中的应用

建立了以静电纺丝聚苯乙烯纳米纤维作固相微萃取载体富集辣椒粉中苏丹红Ⅱ,线性扫描极谱测定的新方法。苏丹红Ⅱ在硼砂-NaOH缓冲溶液(pH11.5)体系中,用线性扫描极谱法测定,在Ep=-0.93V处产生了一个灵敏的还原峰。峰电流(ip)与苏丹红Ⅱ浓度在2×10-2～2×10-1mg/L范围内呈线性关系,相关系数r=0.9947,检出限为3×10-3mg/L。此法用于辣椒粉中苏丹红Ⅱ的检测,回收率在78.0%～85.7%。     

The differential pulse polarographic determination of trace amounts of tin and its application to zinc-aluminium alloys

A differential pulse polarographic procedure for the determination of 0.001-0.02% of tin in zinc-aluminium alloys is described. The tin is first separated from interfering elements such as copper and lead by homogeneous co-precipitation with aluminium succinate. The tin is determined polarographically in a 1M hydrochloric acid + 4M ammonium chloride electrolyte. After the tin has been masked with alkaline citrate a second polarogram is recorded to ascertain whether residual lead is present and, if so, a correction is applied.     

The determination of glycerol : General introduction: volumetric determination as the copper complex

A method for the determination of glycerol by means of the copper-glycerol complex is described; the complex is filtered free of excess copper(II) hydroxide and the copper is determined iodimetrically. Earlier difficulties due to adsorption of the complex are overcome by the use of glass-fibre filter discs. The method gives accurate results in the range 40-4% glycerol in the solution (400 to 40 mg glycerol in the aliquot taken).     

Spectrophotometric determination of thallium in zinc and zinc-base alloys with iodoacetic acid and hexamethylenetetramine

Thallium(III) forms a ternary complex of yellow colour with iodoacetic acid and organic bases, especially hexamethylenetetramine. The complex is soluble in water and various organic solvents. Zinc, copper, cadmium and iron do not form complexes with these reagents, so that a spectrophotometric determination of thallium in zinc and its alloys is possible. The limit of detection is 15 gg^–1, the molar absorption coefficient about 2000 mol^-1l^-1cm^-1.     

The uranium-Xylidyl Blue I complex and its application in linear sweep polarography

The linear sweep polarographic wave of the uranium-Xylidyl Blue I complex in ethylenediamine-1,10-phenanthroline-hydrochloric acid medium has been studied. The complex, corresponding to UO(2)(XBI)(2-)(2) with log beta' = 9.09 (by polarography), 8.81 (by spectrophotometry), is strongly adsorbed on the surface of the mercury electrode. The polarographic wave is attributed to the reduction of Xylidyl Blue I in the complex. The method is very sensitive with a detection limit of 3 x 10(-8)M. The wave height is proportional to the concentration of uranium over the range 8 x 10(-8)-7 x 10(-6)M. Solvent extraction is used to separate possible interferences. The recommended procedure has been applied to the determination of trace amounts of uranium in ores.     

General expression of the linear potential sweep voltammogram in the case of diffusionless electrochemical systems

The equation of the linear potential sweep voltammogram is derived for any degree of reversibility of the electrochemical reaction for the following methods: surface voltammetry when both the oxidized and the reduced forms are strongly adsorbed, and a Langmuir isotherm is obeyed, thin layer voltammetry, and linear potential sweep coulometry. The results are expressed in one mathematical form valid for the three cases. The transfer coefficient and the rate constant of the electrochemical reaction can be deduced from an experimental study of the variations of the peak potentials as a function of the sweep rate.     

Determination of hydrogen peroxide in pickling baths for copper alloys by linear sweep voltammetry

Hydrogen peroxide in pickling baths for copper and copper alloys can be determined by linear sweep voltammetry with a glassy carbon electrode. The oxidation mechanism changes around 0.15 M H₂O₂. Catalytic decomposition was found to be much smaller at glassy carbon electrodes than at platinum electrodes. An almost linear calibration curve was obtained up to 60 mM H₂O₂. Interferences from Cu²⁺, Zn²⁺, Ni²⁺, Al³⁺, Fe³⁺ and Pb²⁺ as well as from the stabilizers were small. All measurements were made in sulphuric acid solutions.     

茜素黄R与蛋白质相互作用的线性扫描极谱法研究及分析应用

以电化学方法研究了在pH3.2的Britton Robinson(B R)缓冲溶液中茜素黄R与蛋白质的相互作用。茜素黄R在-0.43V(vs.SCE)有一个良好的极谱还原峰,加入人血清白蛋白(HSA)后,其峰电位不变而峰电流下降,利用峰电流的下降可以测定蛋白质。优化了结合反应条件和电化学测定条件,在最佳条件下,峰电流降低值同HSA的质量浓度在4.0～40.0mg L范围内呈线性关系,其线性方程为ΔI″p(nA)=-5.48 72.28ρ(mg L),r=0.993。将该方法应用于人血清样品的测定,结果与经典的考马斯亮蓝G 250光度法一致,回收率在97%～103%之间。此方法还可应用于牛血清白蛋白、牛血红蛋白、卵清白蛋白等蛋白质的测定。     

A specific method for the determination of uranium in ores by cathode ray polarography

A method is presented for the specific determination of uranium in ores by cathode my polarography. The uranium is separated by a simple and rapid mercury-cathode electrolysis, then determined polarographically in a base electrolyte in which vanadium, titanium and tungsten do not interfere. Application of the method to the analysis of ten standard uranium ores is shown.     

The application of 2,4,6-trinitrobenzene-1-sulphonic acid in the differential pulse polarographic determination of amines

The differential pulse polarographic behaviour of 2,4,6-trinitrophenyl (TNP) derivatives of several primary amines and amino acids was investigated in the presence of sulphite ion. All the derivatives produced a polarographic peak for their complexes with sulphite (1 × 10^?2 M) in pH 8.0 phosphate buffer (0.05 M)/0.1 M potassium chloride. The derivatives of proteins and peptides did not give such a peak. A 5-min reaction time at room temperature (or 50°C for lysine) and pH 10.5 using 1 × 10^?4 M 2,4,6-trinitrobenzene-1-sulphonic acid provides the optimal conditions for the determination of 5 × 10^?6?2.5 × 10^?5 M amines. The relative standard deviation for determining 1 × 10^?5 M glycine (n = 5) was 1%.