The determination of cobalt,iron plus vanadium or manganese in soft magnetic alloys

A convenient ion exchange separation particularly designed for the separation of iron and vanadium or mangenese from cobalt has been developed for the determination of iron, cobalt and manganese or vanadium in soft magnetic alloys. After an anion exchange separation of their chloride complexes these elements are determined by a back titration of an excess of EDTA with a standard copper solution using calcein as an indicator under ultraviolet light.     

The microchemical analysis of ferrous and non-ferrous alloys

Satisfactory methods are described for the determination of certain of the alloying constituents in small quantities of steels, aluminium alloys and white metals. In steels, lead is determined by using an extraction procedure with dithizone, whereas the stable colour produced by vanadium with 3 : 3' dimethylnaphthidine is used for determining this element. In aluminium alloys, absorptiometric procedures are recommended for determining copper, nickel, iron and manganese. The determination of silicon is advocated by the absorptiometric technique. For the determination of antimony, in white metals, a micro volumetric procedure with standard potassium bromate is recommended using α-naphthaflavone as indicator.     

Determination of iron, nickel, chromium and vanadium by means of redox and ion-exchange columns

Redox and anion-exchange columns have been used to separate and determine iron, nickel, chromium and vanadium in solution. The anion-exchange columns provide some of the separations, and the redox columns are used for the determination of the iron, chromium and vanadium. The chromium and vanadium may be determined in the presence of the iron by adjustment of the acidity in the redox column. By using a column "memory" technique, titration of the actual metal solution has been avoided. The method shows some advantages over conventional methods.     

n-arylhydroxamic acids as reagents for vanadium(v) : Spectrophotometric determination of vanadium(v) with n-m-tolyl-p-methoxybenzohydroxamic acid

A study of the coloured complexes of 51 N-arylhydroxamic acids with vanadium(V) in hydrochloric acid media is described. The absorption spectra of the coloured chloroform extracts and the molar absorptivities are compared. The effects of different substituents attached to the carbon and nitrogen atom of the hydroxamic acid functional group are discussed. A rapid extraction-spectrophotometric method for the determination of vanadium(V) is described, employing the most promising of these reagents, N-m-tolyl-p-methoxybenzohydroxamic acid. The method is highly selective and tolerates large amounts of diverse ions usually associated with vanadium-bearing materials including iron(III), aluminium(III), chromium(III), nickel(II), cobalt(II), zinc(II) and manganese(II).     

Electrochemical Determination of Inorganic Contaminants in Automotive Fuels

This article critically reviews the electroanalytical methods developed for the determination of inorganic contaminants in automotive fuels. Topics include the methods applied to the analysis of liquid biofuels and liquid fossil fuels for which different strategies were developed based on analytes and sample matrices. Special attention is given to electrodes, detection techniques, and sample preparation protocols (when required). Analytes include anions such as chloride, sulfate and phosphate, and mainly metallic species such as sodium, potassium, magnesium, calcium, cadmium, copper, iron, lead, manganese, mercury, nickel, platinum, tin, vanadium, and zinc. Suggestions for future research are also presented.     

The simultaneous determination of vanadium,chromium, manganese,iron, cobalt,nickel, copper and zinc in sea water by x-ray fluorescence sectrometry

A procedure is described for the determination of microgram quantities of the elements vanadium, chromium, manganese, iron, cobalt, nickel, copper and zinc in sea water. Separation and concentration of these elements from a large salt matrix, in order to prevent interferences in the subsequent X-ray fluorescence spectrometry, is achieved by continuous solvent extraction. Ammonium pyrrolidine dithiocarbamate is used as a chelating agent, and the chelated trace elements are quantitatively extracted at a pH of ca. 2.5 into methyl isobutyl ketone. Detection limits of 0.14 μg or better are obtained when a 600-sec counting period is used for X-ray fluorescence spectrometry.     

过敏性哮喘患者血清中10种必需微量元素水平的研究

３４例过敏性哮喘患者血清中铁，锌、铜，锰硒铬，钴镍，钡，钼的含量水平与对照组比较，揭示：（１）铁，铜，铬的含量升高；（２）硒，镍，钴、钒的钼的含量降低；（３）锌和锰的含量差异无显著性，Ｐ〉０．０５。     

116例冠心病患者血清中10种必需微量元素水平的研究

１１６例冠心病患者血清中１０种必需微量元素的含量与正常值比较，具有如下特点：（１）铁，锌、铬，镍含量升高；２硒钴，钒，钼含量降低；（３）铜和锰差异无显著性。     

Titrimetric determination of U(iv) alone and in mixtures with V(IV), Mn(II), Ce(III) and Fe(II)

Summary A rapid and accurate method is described for the potentiometric determination of uranium(IV) with permanganate at room temperature using trace amounts of ortho-phosphoric acid as a catalyst. The procedure has been extended for the differential potentiometric determination of mixtures with vanadium, manganese or cerium. The methods are easy, non-time consuming and free from interference by a large number of foreign ions. Conditions are also developed for the differential photometric determination of uranium and iron in mixtures.Based on these procedures, a differential titrimetric procedure has been developed for determination of iron(III), vanadium(V), chromium(VI) and manganese(VII) [or cerium(IV)] in a single solution at room temperature. This procedure has also been tested on Bureau of Standard samples.

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Titrimetrische Bestimmung von U(IV) allein und in Mischungen mit V(IV), Mn(II), Ce(III) und Fe(II)Anwendung auf die Analyse von Stählen und Legierungen

Zusammenfassung Eine schnelle und genaue Methode wird beschrieben zur potentiometrischen Bestimmung von Uran(IV) mit Permanganat bei Raumtemperatur unter Verwendung von Spuren Orthophosphorsäure als Katalysator. Das Verfahren wurde auf die differentialpotentiometrische Bestimmung im Gemisch mit V, Mn und Ce ausgedehnt. Die rasch und einfach ausführbare Methode wird durch zahlreiche Fremdionen nicht gestört. Eine differentialphotometrische Bestimmung von U(IV) und Fe(II) im Gemisch wird ebenfalls angegeben, außerdem eine differentialtitrimetrische Bestimmung von Fe(III), V(V), Cr(VI), Mn(VII) [oder Ce(IV)] in einer Lösung. Anwendungsbeispiele für Stähle und Legierungen werden beschrieben.

     

Titration of vanadium(IV) with cerium(IV) sulphate, with ferroin as indicator, in aqueous acetone as facile reaction medium An analytical and mechanistic study

A new procedure for the titration of vanadium(IV) with cerium(IV) sulphate, with ferroin as indicator, in aqueous acetone medium is reported. A differential determination of iron(II) and vanadium(IV) is also possible. A probable mechanism for the fast ferriin-vanadium(IV) reaction in acetone medium is given.     

Titrimetric determination of vanadium(IV) with cerium (IV)sulphate at room temperature using ferroin as indicator

A procedure has been developed for the visual titrimetric determination of vanadium(IV) with cerium(IV) sulphate, using ferroin is redox indicator. The method has been extended to the determination of iron(II) and vanadium(IV) in mixtures.     

Determination of manganese,iron, cobalt and nickel in air and water by atomic absorption spectroscopy

Flames of 4 different kinds and of various compositions were studied for their suitability for atomic absorption spectroscopy for the determination of manganese, iron, cobalt and nickel. The effects of various other factors such as lamp current, slit-width and position of the burner were also investigated. Interference effects of a large number of ions and compounds were studied. Very few ions were found to interfere and means of eliminating the interferences noted are described. As a result of the investigation, sensitive and selective procedures for the determination of manganese, iron, cobalt and nickel are reported. Sensitivities are Mn, 0.01 mg/l; Fe, 0.05 mg/l; Co, 0.03 mg/l and Ni, 0.02 mg/l for 1% absorption.     

A new oxidimetric reagent: potassium dichromate in a strong phosphoric acid medium--VII. Photometric titration of vanadium(IV) and of cerium(III) alone and in mixtures with iroN(II)

Vanadium(IV) can be accurately titrated with potassium dichromate in media containing phosphoric acid of 3-12M concentration: the change in absorption of vanadium(IV) is followed in the region 660 mmicro using a red filter. It is more convenient to carry out the titration in 3M phosphoric acid because at higher concentrations chloride, nitrate, cerium(III) and manganese(II) may interfere. Photoelcetric titration is more convenient than potentiometric because the former can be made in a 3M phosphoric acid medium, whereas the latter is possible only in 12M phosphoric acid. The simultaneous differential photometric titration of iron(II) and vanadium(IV) is also possible. Conditions have been found for the photometric titration of cerium(III) and of cerium(III) plus iron(II). The titration is carried out (at 450 mmicro or with a blue filter) in about 10.5M phosphoric acid. Application of the method to a cerium mineral is considered.     

The determination of uranium in alloy systems

A procedure is described for the determination of the uranium content of metallurgical alloys containing this element as a minor constituent. The uranium is first separated from the sample solution by precipitation as uranyl ammonium phosphate in the presence of ethylenediamine-totra-acetic acid. By this means the uranium is separated from many elements including iron, chromium, copper, nickel, vanadium, cerium, ncodymium and bismuth. Tho uranyl ammonium phosphate precipitate is dissolved in hydrochloric acid and the resulting solution is passed through a lead reductor. The tetravalent uranium is titrated with a standard cerie sulphate solution, using ferroin as the indicator. This procedure has proved very suitable for the analysis of bismuthuranium binary alloys containing uranium in amounts up to approximately 20%.     

The determination of aluminum,nickel, cobalt,copper, and iron in alnico

A method has been developed for the determination of the major constituents of Alnico based on an anion exchange separation of the chloride complexes and the subsequent determination of aluminum, nickel, copper, cobalt and iron with EDTA. The method is more convenient than conventional classical methods.     

116例冠心病患者血清中铜铬锰钴镍钒含量的探讨

测定了１１６例冠心病患者血清中铜、铬、锰、钴、镍、钒的含量并与正常值比较，显示含量升高才是有铬和镍，降低者有钴和钒、无差异者有铜和锰。     

Thermal effects and vibrational corrections to transition metal NMR chemical shifts

Both zero-point and classical thermal effects on the chemical shift of transition metals have been calculated at appropriate levels of density functional theory for a number of complexes of titanium, vanadium, manganese and iron. The zero-point effects were computed by applying a perturbational approach, whereas classical thermal effects were probed by Car-Parrinello molecular dynamics simulations. The systematic investigation shows that both procedures lead to a deshielding of the magnetic shielding constants evaluated at the GIAO-B3 LYP level, which in general also leads to a downfield shift in the relative chemical shifts, delta. The effect is small for the titanium and vanadium complexes, where it is typically on the order of a few dozen ppm, and is larger for the manganese and iron complexes, where it can amount to several hundred ppm. Zero-point corrections are usually smaller than the classical thermal effect. The pronounced downfield shift is due to the sensitivity of the shielding of the metal centre with regard to the metal-ligand bond length, which increase upon vibrational averaging. Both applied methods improve the accuracy of the chemical shifts in some cases, but not in general.     

Extractive separation and spectrophotometric determination of tungsten as ferrocyanide

Tungsten, in amounts ranging from micrograms to milligrams, can be extracted into isoamyl alcohol, as the tungsten(V) ferrocyanide complex obtained by reduction of tungsten(VI) with tin(II) in 4M hydrochloric acid containing ferrocyanide. It can thus be separated from iron, cobalt, chromium, manganese, arsenic, antimony, bismuth, silicon, calcium and copper, their precipitation being prevented by addition of glycerol and, in the case of iron, sulphosalicyclic acid. Molybdenum, vanadium and nickel are not separated from tungsten, however. Tungsten can also be determined spectrophotometrically as tungsten(V) ferrocyanide. The absorbance of the brown complex is measured in aqueous solution or preferably after extraction into isoamyl alcohol. As many alloying elements interfere, they should be separated by the ferrocyanide extraction or other suitable method. Both the separation and the determination methods give satisfactory results with an overall error of not more than 0.5% in the analysis of practical samples containing low or high percentages of tungsten.     

Vanadium(III) as an analytical reagent: The titrimetric determination of iron, copper, thallium, molybdenum, uranium, vanadium, chromium and manganese

Vanadium(III) solutions can be used in direct titrations of iron(III), copper(II), thallium(III), molybdenum(VI), uranium(VI), vanadium(V), chromium(VI) and manganese(VII) in milligram amounts. The titrations are done at 70-80 degrees for iron(III), copper(II), thallium(III), molybdenum(VI) and at room temperature for vanadium(V), chromium(VI) and manganese(VII). Uranium(VI) is titrated at 70-80 degrees in presence of iron(II). The vanadium(III) solution is prepared by reduction of vanadium(V) to vanadium(IV) with sulphur dioxide, followed by addition of phosphoric acid and reduction with iodide, and is reasonably stable.     

Transition metal coordination chemistry ofN,N-bis(2-{pyrid-2-ylethyl})hydroxylamine

Although directly relevant to metal mediated biological nitrification as well as the coordination chemistry of peroxide, the metal complexes of hydroxylamines and their functionalized variants remain largely unexplored. The chelating hydroxylamine ligand N,N-bis(2-{pyrid-2-ylethyl})hydroxylamine can be readily generated via a solvent free reaction in high purity; however, the ligand is prone to decomposition which can hamper metal reaction. N,N-bis(2-{pyrid-2-ylethyl})hydroxylamine forms stable complexes with chromium(III), manganese(II), nickel(II), and cadmium(II) ions, coordinating in a side-on mode in the case of chromium and via the nitrogen in the case of the latter three metal ions. The hydroxylamine ligand can also be reduced to form N,N-bis(2-{pyrid-2-ylethyl})amine upon exposure to a stoichiometric amount of the metal salts cobalt(II) nitrate, vanadium(III) chloride, and iron(II) chloride. In the reaction with cobalt nitrate, the reduced ligand then chelates to the metal to form [N,N-bis(2-{pyrid-2-ylethyl})amine]dinitrocobalt(II). Upon reaction with vanadium(III) chloride and iron(III) chloride, the reduced ligand is isolated as the protonated free base, resulting from a metal-mediated decomposition reaction.