Colorimetric determination of tantalum in titanium alloys

Experimental work on tantalum-titanium alloys has been handicapped by the lack of accurate methods for the determination of the tantalum. In this paper a colorimetric procedure is proposed for the determination. The tantalum is separated completely from the titanium by two tannin precipitations with an intervening digestion with tannin. The tannin precipitate is ignited, fused with potassium bisulfate and the melt taken up with ammonium oxalate solution. Pyrogallol is then added and the intensity of the yellow color is measured. A study was made of the tantalum pyrogallol color to obtain optimum conditions. Elements that would be found in the usual tantalum-titanium alloys do not interfere with the method. More than 0.0025 gram of niobium interferes by cauaing occlusion of titanium by the tannin precipitate. This causes high results for tantalum, since titanium reacts with pyrogallol to produce a yellow color. The presence of more than 0.0050 gram of tungsten causes high results for tantalum because tungsten is partially precipitated by the tannin and reacts with pyrogallol to produce a yellow color. The proposed method is recommended for tantalum-titanium alloys containing 0.05 to 5 percent, tantalum.     

Colorimetric determination of iron in titanium alloys

There is need for an improved method for the determination of iron in titanium alloys. In this paper a colorimetric method using o-phenanthroline is proposed. The method is applicable to the range of 0.02 to 9 per cent. iron. Two modifications of a basic procedure are described. One modification, applicable to ordinary titanium alloys, is a direct method. A second modification, applicable to alloys containing large amounts of certain alloying elements, calls for a prior separation of the iron by an ether extraction. In a direct method a one gram sample is dissolved in hydrochloric acid and an aliquot of the solution taken. Hydroxylamine and ammonium tartrate are added, the pH of the solution is adjusted by the addition of sodium acetate, and o-phenanthroline added. A study was made to find the best pH and optimum amount of o-phenanthroline for the development of the color.     

Colorimetric determination of niobium in titanium alloys

There is need for a method for the determination of niobium in titanium alloys, since niobium-titanium alloys are becoming increasingly important. The determination of niobium in this type of alloy is an extremely difficult matter. Many approaches were tried before the problem was solved. In the method proposed in this paper the sample is dissolved in a mixture of hydrofluoric and nitric acids, the solution evaporated to a small volume, and boric acid added. Two tannic acid separations are then made to separate the niobium from the bulk of the titanium. The niobium, is determined colorimetrically by the thiocyanate method using a water-acetone medium. A study was made of the possible interference of elements that might be present in titanium alloys. It was found that the presence of tantalum causes two opposing tendencies. Tantalum can cause high results for niobium because it forms a complex with thiocyanate which is visually colorless but shows some absorption. Tantalum can cause low results for niobium by hindering the development of the niobium color. The resultant effect of the tantalum depends upon the amount of tantalum present, the amount of niobium present and the ratio of tantalum to niobium. The presence of more than one per cent. tungsten can lead to high results for niobium. Other elements that might be present in titanium alloys do not interfere with the method. The procedure is designed for titanium alloys containing 0.05 to 10 per cent. niobium. The method is reasonably rapid. Six determinations can be finished in two days. The method should be applicable to many other materials besides titanium alloys.     

Colorimetric and gravimetric determination of silicon in titanium and titanium alloys

Improved colorimetric and gravimetric methods are proposed for the determination of silicon in titanium and titanium alloys. In the colorimetric method the sample is dissolved in hydrofluoric acid. boric acid added and the; titanium oxidized with hydrogen peroxide and permanganate. The bulk of the titanium is precipitated as a crystalline precipitate by heating in boiling water, and the molybdenum color developed. A portion of the solution is filtered and the transmittance measured. In the gravimetric method the sample is fumed with milfuric acid. the silica ignited and fused with aodium carbonate, The silica is then dehydrated with perchloric acid. Thecolorimetric method is recommended for 0.003 to 1.5% silicon, and the gravimetric method for 0.3 to 5% silicon.     

Colorimetric determination of carbon in titanium

A method is proposed for the colorimetric determination of carbon in titanium. In the method the sample is dissolved in a mixture of sulfuric and fluoboric acids, and nitric acid is added to dissolve the titanium carbide. The solution is boiled and filtered, and the yellow coloration from the nitrated organic complex is read with a spectrophotometer. A spectrophotometric study of the color was made. A comparison was made between the colorimetric determination of carbon in titanium and the colorimetric determination of carbon in steels. The proposed method is rapid and is readily adaptable to the determination of carbon in a large number of samples at one time. The procedure is designed for titanium containing up to 0.7 per cent. carbon. None of the elements encountered in “commercially pure” titanium metal interferes.     

Polarographic determination of aluminum in titanium alloys

Considerable interest has been shown in titanium metal because of its combination of desirable properties, including its favorable strength to weight ratio and its resistance to corrosion. Since titanium-aluminum alloys are fairly common, there is need for an accurate method of determining aluminum over a wide range of concentrations. This paper describes an accurate and fairly rapid polarographic method for determining aluminum based on the reduction of an aluminum-azo dye complex after removing titanium, and other interferences by cupferron precipitation, followed by electrolysis at a mercury cathode when necessary. The reduction takes place at — 0.44 volt versus the saturated calomel electrode in a solution buffered at pH 4.6 with acetate. The method is sensitive from 0.01 mg to 0.50 mg of aluminum per 50 ml, covering a range of 0.005 to 10.0 per cent aluminum.     

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 determination of titanium in alloys by atomic absorption spectroscopy

A method is described for the determination of 0.1–1.2 % of titanium in steels, permanent magnet alloys and cast iron using atomic absorption spectroscopy with hydrofluoric acid solutions and a nitrous oxide-acetylene flame. No preliminary separations are required. When the correct conditions are employed there is no interference from the other elements commonly found in these alloys.     

Extractions with long-chain amines-VIII Colorimetric determination of chromium(VI) with diphenylcarbazide

Traces of chromium(VI) are extracted from sulphuric acid solution into a chloroform solution of trioctylmethylammonium chloride. After the addition of solid diphenylcarbazide to the separated organic phase, a red colour is developed and is measured spectrophotometrically at 550 nm. A great number of common metals, including iron and copper, do not interfere when present in ratios up to at least 1:40,000 (chromium: metal).     

Colorimetric determination ofm-aminophenol

Summary Potassium iodate reacts withm-aminophenol in presence of sulfuric acid to give pink violet color having 5g as visual limit of identification. The color reaction is specific form-aminophenol;o-, andp-aminophenol do not interfere if their amount does not exceed 10 and 70% respectively. This provides a new colorimetric method for the determination ofm-aminophenol in small quantities.

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Zusammenfassung Kaliumjodat reagiert mit m-Aminophenol in Gegenwart von Schwefelsäure unter Bildung einer rosavioletten Farbe mit einer Erfassungsgrenze von 5g. Die Reaktion ist spezifisch; o- und p-Aminophenol stören nicht, sofern nicht mehr als 10 bzw. 70% anwesend sind. Daraus ergibt sich ein neues kolorimetrisches Verfahren zur Bestimmung kleiner Mengen m-Aminophenol.

     

Colorimetric determination of sinalbin

Summary Sinalbin (Sinapinp-hydroxybenzylglucosinolate) is present in white mustard seed(sinapis alba) and on enzymatic hydrolysis liberates a sharp, hot, pungent and flavoury compound,p-hydroxybenzyl isothiocyanate (p-HBI). A new sensitive colorimetric method has been developed in which thep-HBI is reacted with sodium hydroxide to givep-hydroxybenzyl alcohol and sodium thiocyanate. The thiocyanate is converted into cyanogen bromide by reacting it with bromine. The cyanogen bromide is then treated with pyridine—benzidine reagent to give a red colour which has an absorption maximum at 518 nm. The red complex solution obeys Beer's law over the concentration range 0.1–0.5 g of SCN per ml of the solution. One mole of sinalbin gives rise to one mole of thiocyanate ion. Recovery is 90%.

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Zusammenfassung Sinalbin (Sinapin-p-hydroxybenzylglucosinolat) ist ein Inhaltsstoff des Samens von weißem Senf (Sinapis alba) und bildet bei enzymatischer Hydrolyse eine scharf schmeckende, würzig riechende Verbindung, p-Hydroxybenzyl-isothiocyanat (p-HBI). Ein neues kolorimetrisches Verfahren wurde entwickelt, das auf der Reaktion von p-HBI mit Natronlauge beruht, wobei p-Hydroxybenzylalkohol und NaCNS entstehen. Dieses wird mit Brom zu Bromcyan umgesetzt, das seinerseits mit Pyridin-Benzidin eine Rotfärbung mit dem Absorptionsmaximum bei 518 nm gibt. Die Lösung dieser roten Komplexverbindung folgt dem Beer'schen Gesetz von 0,1–0,5 g SCN^–/ml. Ein Mol Sinalbin entspricht einem Grammion Thiocyanat. Die Ausbeute beträgt etwa 90%.

     

Colorimetric determination of manganese

The colour developed, when freshly formed manganese dioxide dissolves in alkaline tellurate solution is found to be suitable for the colorimetric determination of manganese. The colour obeys Beer's law within the concentration range 1.886.10^-4 - 7.54.10^-4M. The colour is developed by oxidizing Mn(II) (in presence of 2.5M alkali) with the equivalent amount of H₂O₂ in the presence of 4 moles of telluric acid per mole Mn(II).     

Colorimetric determination of magnesium

From a critical study of the colorimetric determination of magnesium with titan yellow we concluded that: a. titan yellow must be present in excess; b. a mixture of glycerol and starch solution is satisfactory as protecting colloid; c. the influence of calcium becomes constant with concentrations 10 mg Ca⁺² per 100 ml; d. aluminium, iron, phosphate, ammonium and silica interfere; e. alkali-ions interfere when present in large quantities.The method is rapid and the accuracy is satisfactory and can be recommended for the determination of Mg⁺² in water and in silicates.     

Correction method for X-ray fluorescent determination of chromium in high-alloy steels and nickel-base alloys

Summary A new interelement correction method has been developed for the X-ray fluorescent determination of chromium in high-alloy steels and nickel-base alloys. The calibration equation which was derived from the JIS (Japanese Industrial Standards) model is applicable over wide ranges of compositions by preparation of only Fe-Cr binary standards.The new approach gave better accuracy than that based on Rasberry-Heinrich correction model. The accuracies (_d) were 0.08% for high-alloy steels and 0.14% for nickel-base alloys.

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Korrekturmethode für die röntgenfluorescenzspektrometrische Bestimmung von Chrom in hochlegierten Stählen und Nickellegierungen

Zusammenfassung Die Eich-Gleichung für das neue Korrekturverfahren wurde vom JIS-Modell (Japanese Industrial Standards) abgeleitet und ist über einen weiten Bereich von Zusammensetzungen durch Herstellung von lediglich binären Fe-Cr-Standards einsetzbar. Das beschriebene Verfahren bietet eine bessere Genauigkeit als die Methode nach dem Korrekturmodell von Rasberry-Heinrich. Sie betrug 0,08% für hochlegierte Stähle und 0,14% für Nickellegierungen.

     

Colorimetric determination of water in acetone

A colorimetric method utilising dithizone for the determination of water in acetone is described. The method is based on the change of color with water content, which is possibly due to keto-enol formation of the dithizone. Calibration curves at 608 nm are linear at low water concentrations ; the absorbance decreases with increasing water concentration. A detection limit of 0.02 g of water per 100 ml of solution was obtained. The method is applicable to the determination of water of hydration in metal salts that do not react with dithizone.     

Colorimetric determination of pyrazole in blood

Summary A colorimetric procedure has been developed whereby pyrazole may be determined in blood. The pyrazole is assayed as a reaction product with pentacyanoaminoferrate(III). The method is rapid, straightforward, and will detect levels of pyrazole down to 0.1mol in a total sample volume of 0.2 ml. There appears to be no interfering materials in the serum of normal animals.

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Zusammenfassung Eine kolorimetrische Methode zur Bestimmung von Pyrazol im Blut auf der Basis seines Reaktionsproduktes mit Pentacyanoaminoferrat(III) wurde ausgearbeitet. Sie eignet sich bis zur Größenordnung von 0,1Mol Pyrazol in 0,2 ml Probe. Im Serum normaler Tiere fanden sich keine die Bestimmung störenden Substanzen.

     

Colorimetric determination of anionic detergents

Many types of anionic detergents can be determined colorimetrically by the action of the detergent on a protein-bromcresol purple complex. The amount of free dye liberated from the complex is proportional to the amount of detergent added between certain limits.