Simultaneous polarographic determination of micro amounts of vanadium(V) and molybdenum(VI)

A simple and sensitive polarographic method has been developed for the determination of micro quantities of vanadium(V) and molybdenum(VI), based on the reduction of bromate, which is catalysed by these metal ions in the presence of 2,4-dihydroxyacetophenone oxime. Interference by various cations and anions has been investigated.     

Oxine complex of molybdenum

Molybdenum was reported to be precipitated quantitatively by 8-hydroxyquinoline in the pH range 3.3–7.6, the precipitated compound having the composition MoO₂(ox)₂. The pH range reported and the composition of the complex do not seem to be compatible with present knowledge of the pH stability of anionic and cationic molybdenum. It is now shown that under defined conditions, the precipitate is not formed at pH values higher than 2.24. In several estimations of other metals, molybdenum was masked by using a complexone at high pH values. It is now pointed out, that maintaining the solution at high pH value is itself sufficient and no other external complexing agent is necessary for masking molybdenum.     

Titrimetric determination of vanadium(V) and chromium(VI) alone and in mixtures with hydrazine sulphate in phosphoric acid media

Hydrazine sulphate is proposed as a primary standard reagent for the direct titrimetric determination of vanadium(V) and chromium(VI) alone and in mixtures with potentiometric and photometric end-points, in 9–12 M phosphoric acid medium. The methods proposed possess advantages over those currently available. The use of phosphoric acid as a reaction medium not only accelerates the hydrazine-vanadium(V) reaction very much but also makes it follow an accurate stoichiometric path.     

Extraction and spectrophotometric determination of iron as o-phenanthroline-azide mixed ligand complex

Summary The mixed ligand complex, [Fe(Phen)₂(N₃)₂] can be extracted into nitrobenzene giving a molar absorptivity of 16750 at 510 nm. This is the basis of a photometric method for iron which may be either in the trivalent or bivalent state. The new method is free from interference from a number of substances and is more sensitive than the ferroin method.

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Zusammenfassung Der Eisen-Phenanthrolin-Azid-Mischkomplex [Fe(Phen)₂(N₃)₂] ist mit Nitrobenzol extrahierbar und gibt bei 510 nm eine molare Absorption von 16750. Darauf läßt sich eine photometrische Bestimmungsmethode für zweioder dreiwertiges Eisen begründen. Diese wird von vielen Stoffen nicht gestört und ist empfindlicher als die Ferroinmethode.

     

Synthesis of some new metal-containing polyurethanes

Some new metal-containing polyurethanes were synthesized from manganese and lead salts of mono(hydroxyethyl)phthalate by condensing them with hexamethylene diisocyanate and toluene diisocyanate in dimethylformamide as solvent. The polymers were characterized by viscometry, infrared spectroscopy and thermal analysis. The decomposition temperatures of these polymers were found to be significantly lower than those of metal-free polymers of similar structure. However, the rates of decomposition of metal-containing polyurethanes were lower than those of polyurethanes having no metal. Inherent viscosities in DMSO at 30° of these polyurethanes were low, ranging from 0.043 to 0.067.     

A new oxidimetric reagent: potassium dichromate in a strong phosphoric acid medium—I Titrimetr1c determination of manganese

A new method has been developed for the direct titrimetric determination of manganese^II, depending on its oxidation to manganese^III with potassium dichromate at room temperature in a strong phosphoric acid medium using a potentiometric or photometric endpoint. Oxygen of the air does not interfere. The potentiometric method gives results to an accuracy within ± 0.3% for 20–150 mg of manganese/50 ml of titration solution; with the photometric method 5–17 mg of manganese/40 ml of titration solution can be determined with an error of 0.3–1.0% depending on the amount present. Potassium dichromate in 12.0M phosphoric acid has a formal redox potential of about 1.5 V and this reagent appears to have great possibilities in titrimetric analysis.     

L3/L2 white-line intensity ratios in the electron energy-loss spectra of 3d transition-metal oxides

The L₃/L₂ white-line intensity ratio in transition-metal oxides deviates widely from the statistical value of 2 : 1 but shows interesting systematics. In a series of oxides of a given metal, the ratio reaches a maximum for the d⁵ configuration (e.g. MnO) and a minimum for the d⁰ configuration (e.g. KMnO₄). In a series of monoxides, sesquioxides and dioxides of different metals, the ratio is again a maximum at the d⁵ configuration and decreases as the configuration changes towards d⁰ or d¹⁰. Our results, obtained by electron energy-loss spectroscopy, carried out in an electron microscope, are interpreted on an atomic mechanism involving spin-spin coupling. According to this model, the L₂ transition probability decreases in the progression d⁰ to d⁵ whereas the L₃ transition probability decreases beyond d⁵.     

Titrimetric determination of arsenic(III) with potassium dichromate, using redox indicators

Experimental conditions have been established for the accurate direct titrimetric determination of arsenic(III) with potassium dichromate, using ferroin and N-pnenylanthranilic acid as redox indicators. Interferences have been considered.     

Spectrophotometric determination of ziram, ferbam and zineb with diphenylcarbazone

A procedure has been developed for the determination of ziram (zinc dimethyldithiocarbamate), ferbam (ferric dimethyldithiocarbamate) and zineb (zinc ethylenebisdithiocarbamate) after their decomposition and extraction of the diphenylcarbazone complexes of the zinc or iron into isobutyl methyl ketone. These complexes absorb strongly at 520 nm. The method is rapid, sensitive and selective and can be used for the determination of these dithiocarbamates in commercial and synthetic mixtures.     

Analytical application of embelin

Summary Embelin is employed as a reagent for the gravimetric individual estimation of alkaline earth metals and magnesium.

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Zusammenfassung Zur gravimetrischen Einzelbestimmung von Magnesium und den Erdalkalien wird Embelin als Reagens empfohlen.

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Part III: Z. analyt. Chem. 185, 216 (1962).