Applications,involving the iodide ion: VIII. Direct and indirect determination of mercury(I) and analysis of mixtures. Analysis of chromium(VI)-chromium (III) mixtures. Determination of hypochlorite

Mercury(I), down to 3 ppm, has been accurately determined by direct titration with iodide or by back-titrating excess of iodide with mercury (II) using silver amalgam as the indicator electrode. The direct method and additional volumetric ones were applied to the rapid analysis of various mixtures involving mercury(I) with fair accuracy and precision. Analysis of Cr(VI)-Cr(III) mixtures involved potentiometric back-titration of excess iodide and of excess EDTA separately with mercury(II). Back-titration of excess iodide was successfully applied to the determination of hypochlorite.     

Applications involving the iodide ion: VII. Determination of small amounts of cerium(IV) and analysis of its mixtures with some metal ions

A simple, rapid, and reliable method for cerium(IV) alone; in presence of a variety of cations involving rare earths and iron (III); or in binary, ternary, and quaternary mixtures is given. By its aid 10^?3 down to 1.5 × 10^?5 mole of cerium(IV) were determined with requisite accuracy and precision. The potential breaks detecting the end points ranged from a maximum of 410 to a minimum of 100 mV/0.1 ml of 0.05 or 10^?4M titrant, respectively. Analysis of 15 mixtures using the present method together with other recommended procedures was always much less tedious or time-consuming than reported methods.     

The enthalpimetric determination of mixtures of chloride,bromide and iodide

The individual components of mixtures of chloride (0–1 mmol), bromide and iodide (0–0.1 mmol) may be determined by the use of direct injection enthalpimetry. The heats of reaction of the ions with various reagents have been shown to be additive and the use of non-selective reagents is thus made possible. The amounts of the halides present are calculated by simultaneous equations. The limits of the methods are discussed.     

Qualitative analysis of some alloys and determination of copper and iron by the ring-oven method

Methods for the qualitative analysis of various copper alloys, including ancient Egyptian coins, aluminium alloys and zinc alloys by the ring-oven method, are described. Procedures for the colorimetric determination of copper and iron after separation on the ring oven are given.     

Amperometric determination of hydrogen peroxide in pickling baths for copper and copper alloys by flow injection analysis

The hydrogen peroxide is oxidized at + 1.5 V vs. SCE at a glassy carbon electrode of the wall-jet type. The samples are diluted about 100 times in a dispersion coil before entering the amperometric detector. The calibration curve is linear from 10^?4 to 1 M H₂O₂, when 5-μl samples are used. With 50-μl samples the detection limit decreases to 10^?6 M H₂O₂. Neither metal ions (Cu²⁺, Zn²⁺, Ni²⁺, Al³⁺) up to 0.5 M nor changes in the sulfuric acid concentration of the samples between 0.1 and 1 M interfere with the hydrogen peroxide determination. About 75 samples can be analyzed per hour.     

Application of arsenite reduction to the potentiometric determination of gold and to the analysis of mixtures and alloys

The present work is an application of iodide to the reduction of gold(III), in an attempt to develop new method for gold(III) based on potentiometric back-titration of the excess of iodide with mercury(II). Although it was proved by calculation that the reduction of tetrachloroaurate to the metal should proceed quantitatively to completion, yet our experiments showed that the reduction under ordinary conditions, gave Au(I) in the form of a white precipitate of AuI. We succeeded to push the reduction with iodide to the metal by an excess of ethanol-ether catalyzed iodide at somewhat elevated temperature.With the experimental conditions established a reliable procedure have been developed involving a potentiometric finish which enabled accurate determination of gold(III), either alone or in some of its alloys.     

Spectrophotometric determination of bismuth in copper and cartridge brass by the iodide method

An improved spectrophotometric method is proposed for the determination with iodide of trace amounts of bismuth in copper and cartridge brass. The sample is dissolved in nitric acid and the bismuth is separated from the copper by an ammoniacal precipitation in the presence of iron(III) hydroxide as a gathering agent. The hydroxide precipitate is dissolved in hydrochloric acid, sulfuric acid is added, the solution is evaporated to a few ml, hydrobromic acid is added to volatilize the antimony and tin, and the solution is evaporated to fumes of sulfuric acid. The bismuth iodide color is then developed with a composite potassium iodide—sodium hypophosphite reagent. Factors affecting the bismuth iodide color are investigated.     

Spectrophotometric determination of copper in alloys using naphthazarin

Naphthazarin (5,8-dihydroxy-1,4-naphthoquinone; Naph) is proposed as a chromogenic reagent for the spectrophotometric determination of copper(II). The polynuclear complex has a mole ratio of Cu:Naph=4:6 in a 50% v/v ethanol/water medium containing 0.1 M ammonium acetate and 1.5% (w/v) sodium dodecyl sulfate. The copper-naphthazarin complex shows an absorption maximum at 330 nm with a molar absorptivity of 1.84x10(4) l mol(-1) cm(-1). Beer's law is obeyed up to 4.5 ppm of copper(II). The method was applied for copper determination in alloy samples with satisfactory results.     

Continuous spectrophotometric determination of copper, nickel and zinc in copper-base alloys by flow-injection analysis

Flow-injection methods have been developed for the determination of copper, nickel and zinc in copper-base alloys, including several types of brasses, deoxidized copper, beryllium copper and German silver. The system for copper and nickel involves the measurement of the absorbance of the copper(II) and nickel(II) aquo-complexes at 805 and 410 nm, respectively, after simple dissolution of the sample in a nitric acid-phosphoric acid mixture. The system needs no further reagents and the sample solutions can be analysed at rates of up to 280 /hr for copper (or nickel in German silver) without any carry-over. The system for zinc consists of automatic dilution of the injected sample with a thiosulphate-acetate buffer solution and the subsequent measurement of the absorbance of the zinc-Xylenol Orange complex at 568 nm. This system permits analysis rates of up to 90/hr for zinc solutions, with no carry-over. The procedures have been applied to standard copper-base alloys. The results agreed satisfactorily with the certified values. The precision ranges are 0.2-0.7% for copper and nickel and 0.5-0.8% for zinc.     

Metal analysis in real matrices. Simultaneous voltammetric determination of copper and antimony in alloys

This work addresses the simultaneous determination of copper(II) and antimony(III) in real matrices by differential pulse (DPASV) and fundamental harmonic alternating current anodic stripping voltammetry (ACASV). The voltammetric measurements were carried out using as supporting electrolyte the same acidic mixture (nitric, hydrochloric and perchloric acids) used in the dissolution of the real matrices with proper dilution. The procedure of the sample preparation is thus reduced to one step hence avoiding errors from long and complex sample handlings prior to the instrumental measurement. The results were verified by the analysis of the standard reference materials NBS-SRM 631 Spectrographic Zinc Spelter D-2 and BCS 207/2 Gunmetal. The precision, expressed as relative standard deviation, and the accuracy, expressed as relative error, were, in all cases, less than 5%; the detection limit, for each element and in the experimental conditions employed, was around 10⁻⁷ M. The standard addition technique improved the resolution of the voltammetric method, even in the case of very high metal concentration ratios.     

The determination of sulphur in copper,nickel and aluminium alloys by proton activation analysis

The ³⁴S(p, n)^34mCl reaction induced by 13-MeV protons is used for the determination of sulphur in copper, nickel and aluminium alloys. The ^34mCl is separated by repeated precipitation as silver chloride. The results obtained were 3.08 ± 0.47, 1.47 ± 0.17 and <1μg g^-1 for copper, nickel and aluminium alloys, respectively.     

Applications of pressurized cation exchange chromatography for fission yield determination

In order to determine the fission yields of lanthanides precisely, lanthanides with carriers of 1–2 mg per element are separated from each other by means of pressurized cation exchange chromatography-HIBA concentration gradient elution: The effects of initial loading technique, concentration gradient, flow rate, and temperature on separation were investigated in detail. Under the optimum conditions adopted according to the results given in this work, all the lanthanides can be completely separated within about 90 minutes with a recovery of more than 95% and purity higher than 99%.     

The rapid spectrophotometric determination of copper in non-ferrous alloys

A very simple method has been established for the rapid determination of copper, employing the formation of the chlorocupric anion by means of concentrated hydrochloric acid. The absorption of the chlorocupric anion is measured spectrophotometrically at a wavelength of 950 mμ. The method is applicable to a wide variety of samples, including many non-ferrous alloys.     

Rapid iodometric determination of copper in some copper-base alloys

Copper-base alloys, especially those containing tin, are readily dissolved in a mixture of hydrofluoric and nitric acids. In the resulting solution copper can be titrated iodometrically in the conventional manner.     

Controlled potential electrolytic determination of copper in lead and tin-base alloys

In lead-base alloys, copper can be determined by a single controlled-potential electrolysis if less than 1.5% of antimony is present, otherwise, the deposit must be dissolved and re-electrolyzed Iron tends to inhibit the co-deposition of antimony in tin-base alloys, copper and lead can be determined successively. The sample weight is 5 g; percentages as low as 0.2% can be determined.     

The determination of small amounts of tin in copper and its alloys

Turbidimetric procedures are recommended for the determination of tin, over the range 0.001–0.4%, in copper-base materials. Compared with other known methods, these procedures are simpler and invariably quicker. The procedure using phenylarsonic acid is applicable provided the amount of iron in the sample does not exceed the amount of tin to be determined. In the examination of samples containing alloying amounts of iron and small amounts of tin, the use of a more sensitive reagent 4-hydroxy-3-nitro-phenylarsonic acid, is recommended particularly for the determination of tin below 0.01%. With the exception of iron both procedures are relatively free from interference by common allaoing elements.     

Determination of gold(III) alone or in some mixtures and alloys by potentiometric titration of iodide

The present work is an application of iodide to the reduction of gold(III), in an attempt to develop new method for gold(III) based on potentiometric back-titration of the excess of iodide with mercury(II). Although it was proved by calculation that the reduction of tetrachloroaurate to the metal should proceed quantitatively to completion, yet our experiments showed that the reduction under ordinary conditions, gave Au(I) in the form of a white precipitate of AuI. We succeeded to push the reduction with iodide to the metal by an excess of ethanol-ether catalyzed iodide at somewhat elevated temperature.With the experimental conditions established a reliable procedure have been developed involving a potentiometric finish which enabled accurate determination of gold(III), either alone or in some of its alloys.     

Rapid spectrophotometric determination of copper in iron,steel and ferrous alloys

A rapid spcctrophotometric mcthod for the determination of copper in iron, steel and ferrous alloys without separating the copper has been developed. The sample is dissolved in acid and ammonium citrate is added to complex the iron and other alloying elements. The pH is then adjusted to 8.0–9,5 with ammonium hydroxide. A solution of bis-cyclohexanone-oxalyldihydrazone ia finally added and the absorbance of the blue copper complex formed is measured.