Spectrophotometric determination of ruthenium and osmium

The optimum conditions for preparation of stable solutions of ruthenate and osmate, after alkaline fusion of ruthenium(IV) compounds, ruthenium metal and osmium metal in a silver crucible, have been determined. The molar absorptivities of ruthenate and osmate are 1.74 × 10³ 1. mole⁻¹.cm⁻¹ at 465 nm (Ru) and 2.75 × 10³ 1.mole⁻¹.cm⁻¹ at 340 nm (Os) in 2M sodium hydroxide. A differential spectrophotometric method has been developed for determination of ruthenium in ruthenium dioxide, lead ruthenite and bismuth pyroruthenate. Simultaneous spectrophotometric determination is proposed for ruthenium and osmium. The other platinum metals interfere seriously only when present in> 1:1 w/w ratio to Ru.     

Spectrophotometric determination of ruthenium with 8-quinolinol

A spectrophotometric method is described for the determination of 2–80 μg of ruthenium. The method involves oxidation of ruthenium to ruthenate, addition of 8-quinolinol, adjustment of the pH to 4–6.5, digestion of the complex formed at 85° for 30 min, extraction with chloroform, and measurement of absorbance at 430 nm. Almost all other metals and excess of reagent are removed by washing the extract. About 98 % of ¹⁰⁶Ru tracer was recovered.     

Spectrophotometric determination of ruthenium with diphenylthiovioluric acid

Diphenylthiovioluric acid (DPHTVA) reacts with ruthenium(III) to form a complex which has an absorbance maximum at 520 nm. Effects of pH, heating time, buffer and reagent have been studied. DPHTVA has been found to be a sensitive reagent for ruthenium(III) (sensitivity = 0.0044 μg Ru/cm² for log I₀/I = 0.001), and has been made selective by the use of masking agents. The composition of the complex as revealed by different methods is 1:2 (ruthenium:DPHTVA).     

Spectrophotometric determination of ruthenium with 3,4-diaminobenzoic acid

Ruthenium(III) chloride and 3,4-diaminobenzoic acid, in aqueous solution at pH 4.0-4.5, react slowly at room temperature, but more rapidly when the mixture is heated, giving solutions that go through colour transitions from amber to purple-red; maximum absorbance of fully developed solutions occurs at 550 nm. The effects of heating temperature and time, pH, reagent concentration, and other variables have been studied. The system conforms to Beer's law; optimum concentration range, for measurement in 10-mm cells, is about 0.5-2 ppm of ruthenium. Interference from foreign ions, especially other platinum elements, is avoided by a distillation separation of ruthenium. The spectrophotometric mole-ratio and continuous-variation methods indicated the presence of complexes of 1:2 and 1:3 ruthenium-to-reagent stoichiometry. Elemental analysis of solid products isolated from solution confirmed the 1:2 reaction ratio. Several other o-diamines gave similar coloured solutions and reaction stoichiometry.     

Spectrophotometric determination of ruthenium(III) using diphenylcarbazone

Summary The purple violet ruthenium(III)-diphenylcarbazone complex which is formed at p _h 5–7, and has an absorption maximum at 530 nm with molar absorption coefficient 16.2·10⁴l.cm^–1.mole^–1 is suggested for the estimation of 20–125g ruthenium(III) spectrophotometrically in 30–60% ethanol. The complex is stable over p _h range 3.2–8.4. The limits of interference due to foreign ions have been studied.

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Zusammenfassung Der bei p _h 5 bis7 entstehende Ruthenium(III)-Diphenylcarbazon-Komplex hat ein Absorptionsmaximum bei 530 nm und einen Absorptionskoeffizienten von 16,2·10⁴ l.cm^–1.Mol^–1. Die spektrophotometrische Bestimmung von 20 bis 125g Ruthenium(III) in 30 bis 60%igem Äthanol mit Hilfe dieses zwischen p _h 3,2 und 8,4 beständigen Komplexes wurde vorgeschlagen. Die Störung durch Fremdionen wurde geprüft.

     

Spectrophotometric determination of ruthenium after extraction of perruthenate with benzyltributylammonium chloride

A simple and convenient extractive spectrophotometric method for the determination of ruthenium has been developed. It is based on the oxidation of the different ruthenium (II, III or IV) species to perruthenate with potassium periodate at pH 7.8. The perruthenate is then extracted with benzyltributylammonium chloride in chloroform followed by direct spectrophotometric measurements at 342 and 380 nm. The optimum concentration range was found to be 0.1–5 mg l^–1, the standard deviation ±2.1%. The method has been successfully applied to the determination of ruthenium in organoruthenium compounds.     

Spectrophotometric determination of carbon monoxide with ruthenium(II) octaethylporphyrin

A novel spectrophotometric method for the estimation of carbon monoxide at levels from 2 to 250 ppm is presented. The method is empirical and based on formation of a carbonyl complex of ruthenium(II) octaethylporphyrin and measurement of the difference in absorbance at 393.5 nm between this complex and the porphyrin reagent. Oxygen and nitrogen do not interfere and up to 300 ppm of sulphur dioxide and about 1500 ppm of carbon dioxide can be tolerated in determination of carbon monoxide at the 4 and 10 ppm levels. Hydrogen sulphide interferes and must be removed before the determination. The method has been tested over the range 2-45 ppm of carbon monoxide with 16 synthetic and 2 commercial standard air samples. The average error was +/- 3%. Application to urban-air samples and car-exhaust gases yielded acceptable results. The main disadvantages are the tedious preparation of the initial ruthenium(III)-porphyrin compound and the decomposition of the reagent in the presence of hydrazine.     

Spectrophotometric determination of ruthenium,rhenium, osmium and platinum with organic thiohydrazides

Summary Four organic thiohydrazides, e. g.,-naphthalenethiocarboxhydrazide, 2-pyrrolethiocarboxhydrazide, 2-furanthiocarboxhydrazide and 2-thiophenethiocarboxhydrazide are employed as reagents for the spectrophotometric determination of ruthenium, rhenium, osmium and platinum in the presence of considerable excess of diverse metal ions commonly associated with them. The coloured complexes, formed by the reagents with the metals, are stable for more than 12 hr and follow Beer's law at the wavelength of maximum absorbance. The molar absorptivities are in the 10⁴ range for the metal complexes studied.

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Zusammenfassung Alpha-Naphthalinthiocarboxhydrazid, 2-Pyrrolthiocarboxhydrazid, 2-Furanthiocarboxhydrazid und 2-Thiophenthiocarboxhydrazid wurden als Reagenzien für die spektrophotometrische Bestimmung von Ruthenium, Rhenium, Osmium und Platin in Gegenwart beträchtlicher Überschüsse verschiedener, damit üblicherweise vergesellschafteter Metallionen verwendet. Die dabei gebildeten gefärbten Komplexverbindungen sind mehr als 12 Stunden beständig und folgen dem Beerschen Gesetz bei der Wellenlänge maximaler Extinktion. Die molaren Absorptionen liegen in der Größenordnung 10⁴.

     

Spectrophotometric determination of ruthenium(III) and iridium(TV) with 8-hydroxyquinoIine N-oxide

The spectrophotometric characteristics and the stability constants of the yellow to brown 1:1 and 1:2 complexes of platinum metals with oxine N-oxide (existing as chloro mixed-ligand complexes) have been investigated. Oxine N-oxide can be used as a spectrophotometric reagent for ruthenium(III) and iridium(IV).     

Spectrophotometric determination ofm-phenylenediamine

Summary A mixture of chloranil and cupric chloride-triphenylphosphine complex in acetone gives pinkish red color withm-phenylenediamine which provides the basis of a new spectrophotometric method for the determination ofm-phenylenediamine in minute quantities,o- andp-phenylene-diamines do not interfere with the determination if their amount does not exceed 90 and 7% respectively.

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Zusammenfassung Eine Mischung von Chloranil und Kupfer(II)-chlorid-triphenylphosphin in Aceton gibt mit m-Phenylendiamin(I) eine rosa Färbung, die zur Bestimmung kleiner Mengen von I geeignet ist. o- und p-Phenylendiamin stören nicht, sofern deren Menge 90 bzw. 7% nicht überschreitet.

     

Spectrophotometric determination of osmium

Summary m-Amino benzoic acid in large excess reacts with tetra-, hexa- and octavalent osmium at theph range 4.5–6 to give a purple complex having absorption maximum at 500 nm. Beer's law is obeyed for 0.5 to 8 ppm of osmium(VI) and osmium(VIII) with optimum concentration range of 2 to 8 ppm of osmium(VI) and 3 to 8 ppm for osmium(VIII). The per cent relative error per 1% absolute photometric error is 2.8 for both osmium(VI) and osmium(VIII). Ions such as Pd²⁺, Rh³⁺, Ir⁴⁺, W⁶⁺, U⁶⁺, Co²⁺, Hg²⁺, Mg²⁺, Ca²⁺, Ba²⁺, Sr²⁺, Th⁴⁺ and Zr⁴⁺ do not interfere in the determination.Molar ratio method indicates that the reagent first reduces osmium (VIII) and osmium(VI) to osmium(IV), which then probably forms a 11 complex with the excess unoxidised reagent.Part III.: Anal. chim. Acta 22, 306 (1960); cf. Z. analyt. Chem. 177, 291 (1960).     

Spectrophotometric determination of crotonaldehyde

Summary A spectrophotometric method for determining crotonaldehyde witho-tolidine in glacial acetic acid medium is described. Aromatic aldehydes interfere.

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Zusammenfassung Ein spektrophotometrisches Verfahren zur Bestimmung von Krotonal-dehyd in Eisessiglösung unter Verwendung vono-Tolidin wurde beschrieben. Aromatische Aldehyde stören.

     

Spectrophotometric determination of phenylephrine

This paper describes a spectrophotometric assay procedure for the determination of small amounts of phenylephrine in the presence of a variety of foreign substances including ascorbic acid. This method is based on the formation of a blue colored indophenol derivative from the reaction of phenylephrine with N,2,6-trichloro-p-benzoquinoneimine.     

Spectrophotometric determination of peucedanin

Conclusions A spectrophotometric method has been proposed for determining peucedanin in a crystalline powder and in the roots ofPeucedanum Morisoni Bess.Khimiya Prirodnykh Soedinenii, Vol. 6, No. 1, pp. 3–6, 1970