Chelometric titration of gallium in the presence of indium and other metals by chloride masking

Summary In solutions containing high concentrations of ammonium chloride, indium is masked as the chloro complex and gallium can be titrated in boiling solution with EDTA to a visual end-point using Xylenol Orange as the indicator. Up to a mole ratio InGa of about 300 good results are obtained. The influence of some other metal ions on the titration has been investigated.

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Zusammenfassung Indium wird in Lösungen, die hohe Konzentrationen an Ammoniumchlorid enthalten, als Chlorokomplex maskiert und Gallium kann in kochender Lösung mit ÄDTA titriert werden. Xylenolorange dient als Indicator. Gute Resultate werden noch bei In: Ga-Verhältnissen von ungefähr 300 erhalten. Der Einfluß einiger anderer Metalle wurde untersucht.

     

Selective thermometric titration of manganese(II) with edta

The differential thermometric titrations of mixtures of Mn(II) and Zn(II), or Mn(II) and Cd(II), and the selective thermometric titrations of Mn(II) in the presence of larger amounts of Cu(II) or Ni(II) are described. The optimal conditions for these titrations are considered based on the effective enthalpy.     

Photometric complex-formation titration of submicromole amounts of metal-II The presence of other metals

End-point extrapolation with the aid of a tangent to the spectrophotometric titration curve has been discussed theoretically for the metal-indicator complex MI with a ligand L in the presence of two other metals (P(1) and P(2)). It was found that a titration end-point can only be determined when the reaction of P(1) and P(2) with L takes place only negligibly during the titration of M. Two cases of practical interest can be distinguished. The metals may react either before or after the titration has been completed. For both situations titration conditions have been derived. With these titration conditions suitable experimental conditions can directly be derived from diagrams which were introduced in a previous paper. The theory developed has been applied to mixtures of manganese and magnesium but is generally applicable.     

Automatic derivative spectrophotometric titration of iron and/or aluminum with edta

Automatic derivative spectrophotometric EDTA titration procedures for the determination of iron and/or aluminum are described. Iron is automatically titrated in the presence of aluminum at pH 1.8–3.0 using 3,5-dinitrosalicylic acid as indicator. Total iron and aluminum, or aluminum alone, are determined by adding a small excess of standard EDTA, as visually indicated by the fluorescence of calcein W, with subsequent automatic titration of excess EDTA. The intense color of the iron-EDTA complex causes no difficulty in the automatic method, and macro as well as micro quantities of iron and/or aluminum can be determined with relative errors of 0.3% or less, even when the amount of aluminum is 4 times that of iron.     

Nuclear magnetic resonance studies of edta in the presence of excess calcium or strontium

The equilibria which exist between metal ions, ethylenediaminetetraacetic acid (EDTA), and the resulting chelates have been thoroughly investigated by many techniques, emphasis being placed on the study of complexes containing a 1:1 ratio of metal ion to ligand. The results presented here are concerned with the observation of the chemical shift of the nonlabile protons of EDTA when excess calcium or strontium ions are present. The results yield evidence for a 2:1 complex. Formation constants for the equilibria believed to be in effect are given and a possible structure of the 2:1 complex is discussed.     

Determination of traces of gallium in the presence of aluminium by synchronous derivative spectrofluorimetry

Gallium (2–100 ng ml^?1) is determined in the presence of ?500-fold amounts (by weight) of aluminium by using synchronous first- or second-derivative spectrofluorimetry. The fluorescence of the gallium chelate with 1-(2-pyridylazo)-2-naphthol is greatly enhanced compared to that of the aluminium chelate in micellar sodium dodecyl sulphate solutions. The limit of detection is about 0.6 ng ml^?1.     

Selective amperometric titration of molybdenum with oxine in presence of DCTA

Summary In presence of DCTA molybdenum is selectively precipitated with oxine. The precipitation may be utilized for a volumetric determination with amperometric end-point detection. The influence of the ions which usually accompany molybdenum was established from the values obtained for the conditional solubility products of their oxinates. The behaviour of Cu(II), Fe(III), W(VI) and Al(III) was studied experimentally. It is shown, that Cu, Fe and W are completely masked by DCTA, Al was masked with NH₄F.Correct results are obtained with Mo concentrations in the initial solution >1×10^–5 and 1sx10^–3 M. The standard deviation of the method amounts to ±0.02 mg, while the relative (%) standard deviation varies within 0.2 to 2.0.

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Selektive amperometrische Titration von Molybdän mit Oxin in Gegenwart von DCTA

Zusammenfassung Molybdän(VI) läßt sich mit Oxin in Anwesenheit von DCTA selektiv fällen. Die Reaktion kann zur volumetrischen Bestimmung verwendet werden, wobei der Äquivalenzpunkt amperometrisch ermittelt wird. Der Einfluß von Metallionen wird auf Grund der berechneten relativen Löslichkeitsprodukte der entsprechenden Oxinate geschätzt. Experimentell wurden die Schlußfolgerungen für das Verhalten von Cu(II), Fe(III), W(VI) und Al(III) geprüft. Die ersten drei werden nicht mitgefällt, während Al durch F^–maskiert werden kann. Der Anwendungsbereich der Methode umfaßt Mo(VI)-Konzentrationen >1·10^–5 und 1·10^–3 M. Die Ionen von Cu, Fe, Al und W, sowie diejenigen, welche leichter lösliche Oxinate bilden, stören nicht. Die Reproduzierbarkeit wird durch eine Standardabweichung von ±0,02 mg bzw. eine relative (%) Standardabweichung von 0,2–2,0 charakterisiert.

     

The titration of nickel with edta at ph 2.8

A method for determining nickel using EDTA is described. A small excess of EDTA is added, the pH adjusted to 2.7–2.9 and the solution back-titrated with thorium nitrate, against ahzarin-S as indicator. Quantities of cobalt up to 10 mg do not interfere.In addition an approximate determination of the complex-forming constant of Th-EDTA is described, based on the decrease in extinction of an Ni-EDTA solution to which Th⁺⁴ has been addd.     

Photometric titrations—X The edta titration of iron(III) in the presence of high concentrations of bismuth

In solutions containing a high concentration of ammonium chloride, bismuth is masked as the chloro complex, and iron(III) can be titrated with EDTA to a photometric end-point using sulphosalicylic acid as the indicator. Up to a mole ratio Bi:Fe of about 2,000, good results are obtained. At higher ratios slightly high results are obtained for the iron. The influence of some other metal ions on the titration has been studied.     

Determination of penicillins by desulphurization with lead and edta titration

A new, simple, accurate and rapid method is described for the determination of total penicillins in pharmaceutical preparations. The method is based on desulphurization with potassium plumbite whereby one mole of lead sulphide is formed per mole of penicillin. The excess of lead ions is titrated with EDTA at pH 4.5, with use of the lead ion-selective electrode. Results are reproducible within +/- 0.5% and compare favourably with those obtained by the procedures of the United States and British Pharmacopoeias.     

Determination of aluminium in plain steel using edta and dichlorodiethyl ether

A. gravimetric method for determining aluminium in steel has been developed. This involves the separation of iron. using steam-distilled dichlorodiethylether and the precipitation of aluminium from the disodium salt of EDTA.     

Hydrogenation of fullerites in the presence of intermetallic compounds or metals

Fullerene hydrides containing 24–26 H atoms per fullerene molecule were obtained by hydrogenation of solid-phase mixtures of fullerenes with either intermetallic compounds LaNi₅, LaNi_4.65Mn_0.35, CeCo₃ or V and Pd metals with gaseous hydrogen at 1.0–2.5 MPa and 573–673 K. These fullerene hydrides decompose at 800 K with evolution of H₂. Upon subsequent heating to 1000 K, vanadium reacts with fullerene to yield a cubic phase of vanadium carbide. The intermetallic compounds react with fullerene with the formation of a metallic phase of the 3d-metal and destruction of fullerene. Palladium does not react with fullerene. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 679–683, April, 1997.     

Direct edta titration of vanadium(v) using variamine blue b base as indicator in the presence of excess iron(II)

Continuous expressions are derived for the titration of vanadium(V) with iron (II) in the presence of excess EDTA and for the titration of vanadium(V) with EDTA in the presence of excess iron (II). A new method of EDTA titration of vanadium(V) is developed based on the theoretical consideration of these expressions. The method is simple, selective and reliable.     

Determination of semimicro amounts of calcium in the presence of other alkaline-earth metals

Cyclam tetraacetic acid (CTA) is used to determine semimicro quantities of calcium in the presence of other alkaline-earth metals in natural and synthetic water samples. End-point detection is achieved amperometrically with Zn(en)(2+)(3) as the indicator. Magnesium and barium do not interfere. In the presence of strontium, two distinct end-points are obtained when its concentration is comparable with that of the calcium. If the concentrations are substantially different, calcium and strontium appear to be titrated together.     

Microdetermination of ruthenium(III) in presence of other metals

Summary Ruthenium(III) reacts with thiovioluric acid in aqueous medium at p_H 4.45–6.00 to yield pinkish-violet complex with absorption maximum at 540 nm. Full colour development requires heating for about 30 minutes on a boiling water bath. The system obeys Beer's law in the range 0–5.6 ppm of ruthenium. The sensitivity of the reaction is 0.0046g/cm² (for log 10/I=0.001) at 540 nm. The composition of the complex is 12, as shown by Job's and Bent and French methods. The effect of various foreign ions in the determination of ruthenium has also been investigated.

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Zusammenfassung Ruthenium(III) reagiert mit Thioviolursäure in wäßriger Lösung bei p_H 4,45–6,00 unter Bildung einer rosa-violetten Komplexverbindung mit dem Absorptionsmaximum bei 540 nm. Die volle Farbentwicklung tritt beim Erwärmen auf dem siedenden Wasserbad in etwa 30 min. ein. Das Beer'sche Gesetz ist bis 5,6 ppm Ru erfüllt. Die Empfindlichkeit der Reaktion beträgt 0,0046g/cm² bei 540 nm. Die Zusammensetzung des Komplexes entspricht dem Molverhältnis 12. Der Einfluß verschiedener Fremdionen wurde untersucht.

     

Direct heterometric microtitration of nickel with dimethylglyoxime in the presence of other metals

A new “heterometric” method was presented for a quick, direct determination of small quantities (< 1 mg) of nickel (~2%) in the presence of other metals (~98%). The error was between zero and 1.4 micrograms of nickel per ml, or between zero and 3% of nickel.     

Direct heterometric microtitration of copper with oxine in the presence of other metals

A new heterometric method is presented for a rapid micro-determination of copper with oxine. 1 mg of copper in 20 ml of solution may be determined with an accuracy of 0-I-0 microgram per ml. The solution may contain 95% Me or Al, 98% Zn, Mn, Co. Ni, Cd or Cr and 99-8% Pb. The determination is made at room temperature and takes 10–20 minutes.     

Anion-exchange separation of gallium from indium,thallium, aluminium and other elements in malonic acid

Summary Systematic studies of gallium on Dowex-21K in malonate media are reported. On the basis of the value of the elution constant (E) it was separated from large number of metal ions. By selective sorption it was separated from the alkalis, alkaline earths, bismuth, thallium (I), mercury (II), iron (II) and germanium (IV). With water as eluant it was separated from cobalt, nickel, zinc, manganese and palladium, with ammonium chloride it was possible to separate it from copper, iron and vanadium, and with a specific eluant it was separated from lead and zirconium. Finally the sequential separation of gallium from thallium, aluminium and indium was accomplished.