Spectrophotometric determination of uranium with 1-(2-pyridylazo)-2-naphthol

1-(2-Pyridylazo)-2-naphthol (PAN) rcacts with uranium to form a deep red precipitate in ammoniacal solutions, this can be extracted with chloroform if sodium chloride or sulfate is added and it has a maximum absorption at 560 mμ The color is stable and follows Beer's law. Trace amounts of uranium may be determined in the presence of many metals without prior separation if strong complexing agents, such) as EDTA or cyanide, are added     

Spectrophotometric extractive titrations-VI Titrations with 1-(2-pyridylazo)-2-naphthol

The possibility of using PAN as a titrant in spectrophotometric extractive titrations has been investigated. Conditions suitable for the titration of zinc and of cadmium were found, with the aid of equations derived earlier and after investigation of the absorption spectra and pH- and reagent-dependence of the extraction of the chelates involved. For the purpose of spectrophotometric extractive titration of copper with PAN the formation and extraction of ion-association pairs CuPAN(+).Br(-) and CuPAN(+).CNS(-) were studied in detail. This titration was found to be highly selective. Dilute solutions of PAN in ethanol are much more stable than solutions of dithizone.     

Spectrophotometric studies and analytical application of Ce(III) chelates with 1-(2-pyridylazo)-2-naphthol (PAN)

A sensitive procedure for spectrophotometric determination of cerium(III) has been developed. AtpH 10.2 cerium reacts with 1-(2-pyridylazo)-2-naphthol in 40% ethanol to form a red complex which has an absorption maximum at 545 nm. The molar absorptivity at 545 is 3.95·10³ mol^–1. Maximum stability of the complex was attained in pure ethanol. The stoichiometries and structures of the chelates were studied applying conductometric titration, visible spectrophotometry and IR spectrophotometry. The IR spectra revealed that coordination takes place through the N=N, C-OH and pyridyl group.

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Spektrophotometrische Untersuchungen und analytische Anwendung von Ce(III)-Chelaten mit 1-(2-Pyridylazo)-2-naphthol (PAN)

Zusammenfassung Es wurde eine empfindliche Methode zur spektrophotometrischen Bestimmung von Cer(III) entwickelt. Bei einempH von 10,2 reagiert Cer mit 1-(2-Pyridylazo)-2-naphthol in 40% Ethanol unter Bildung eines roten Komplexes mit einem Absorptionsmaximum bei 545 nm (=3 950). Der Komplex besitzt in reinem Ethanol ein Maximum an Stabilität. Die Stöchiometrien und Strukturen der gebildeten 1:1- und 1:2-Chelate wurden mittels konduktometrischer Titration, Elektronen- und IR-Spektrometrie untersucht. Die IR-Daten zeigen, daß die Koordination über N=N, C-OH und Pyridyl erfolgt.

     

Colorimetric determination of zirconium with 1-(2-pyridylazo)-2-naphthol

A method is described for the determination of as little as 50 ppm of zirconium in uranium-fission element alloys and zinc magnesium-uranium-fission element alloys. Zirconium is extracted from a nitric acid-aluminium nitrate medium with dibutyl phosphate in toluene. The uranium co-extracted with the zirconium is removed by scrubbing with hydrochloric acid-ammonium thiocyanate solution. A portion of the organic phase is mixed with pyridine-toluene solution of 1-(2-pyridylazo)-2-naphthol to develop the colour.     

Preparation and properties of a new chelating resin containing 2-nitroso-1-naphthol

A new chelating ion-exchange resin based on a macroreticular polystyrene—divinyl benzene copolymer and containing 2-nitroso-1-naphthol as the functional species has been synthesized. It is highly stable in acidic and alkaline solutions. Its sorption characteristics for V(V), Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Hg(II), Pd(II) and U(VI) have been investigated over the pH range 1.0–7.0 and the exchange-capacities have been found to be generally higher than those of a similar resin containing 1-nitroso-2-naphthol.     

Spectrophotometric determination of cobalt with 1-(2-pyridylazo)-2-naphthol and surfactants

A simple and highly selective spectrophotometric method for the determination of cobalt based upon the rapid reaction with PAN in the presence of surfactants and minute amounts of ammonium persulphate at pH 5.0 is described. The cobalt(III) chelate is made water-soluble by a neutral surfactant. Triton X-100, combined with sodium dodecylbenzene sulphonate (DBS). Iron(III), bismuth, tin(IV) and aluminium are masked with oxalate or citrate. Iron(II) must be absent. The other metal-PAN chelates, except that of nickel, are readily decomposed by EDTA. Up to 150 microg of nickel does not interfere. When larger amounts up to 625 microg are present, the absorbance can be corrected by measurements at two wavelengths. In a strongly acid medium (below pH 0.5) the nickel and other metal chelates are completely and instantaneously decomposed, while the cobalt(III) chelate remains unchanged. When, in place of EDTA, several ml of 6M hydrochloric acid are added after the colour development, nickel in quantities up to 1250 microg can be tolerated. A several hundredfold excess of zinc and manganese does not interfere. At 620 nm Beer's law is obeyed over the cobalt concentration range 0.4-3.2 microg/ml. The precision (95% confidence) is +/- 1.0 microg for 100 microg of cobalt. The molar absorptivity is 1.90 x 10(4) l. mole(-1) .cm(-1).     

Complexes of organolead and organotin ions with 1-(2-pyridylazo)-2-naphthol

The stability constants of the complexes of 1-(2-pyridylazo)-2-naphthol with several organotin and lead ions were determined spectrophotometrically in aqueous 20% (v/v) dioxane and were shown to have very high values. The extraction of the complex of (C₂H₅)₂Pb²⁺ from water into chloroform was studied, and the formation of an extractable (C₂H₅)₂Pb(PAN)(OH) complex is postulated.     

Spectrophotometric determination of hafnium(IV) with 1-(2-pyridylazo)-2-naphthol

Summary The red complex formed between hafnium(IV) and 1-(2-pyridylazo)-2-naphthol (1 2) at pH 4.0 is used for Spectrophotometric determination of hafnium., the absorbance being measured at 545 nm. Beer's law is obeyed for hafnium concentration of 0.2 to 3.6g per ml. Molar absorptivity is 3.86×10⁴ and Sandell sensitivity is 0.0046g per cm². Hafnium has been determined in the presence of 6-fold amounts of zirconium. The relative standard deviation is ± 1.0%.

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Zusammenfassung Der rote, bei pH 4,0 sich bildende Komplex mit 1-(2-Pyridylazo)-2-naphthol (1 2) dient zur Bestimmung von Hafnium (IV). Seine Extinktion wird bei 545 nm gemessen. Zwischen 0,2 und 3,6g Hf/ml ist das Beersche Gesetz gültig. Hafnium läßt sich in Gegenwart der sechsfachen Menge Zirkonium bestimmen. Die relative Standardabweichung beträgt ± 1,0%.

     

Spectrophotometric determination of manganese with 1-(2-pyridylazo)-2-naphthol and a non-ionic surfactant

A spectrophotometric method for the determination of trace amounts of manganese with 1-(2-pyridylazo)-2-naphthol (PAN) is described. The method is based on the measurement of absorbance of the manganese—PAN chelate solubilized with a non-ionic surfactant, Triton X-100. No extraction procedure is required in the method proposed. High concentrations of calcium, aluminium and magnesium do not interfere. The presence of up to 10 ppm of lead can be tolerated. Iron, cadmium, zinc, cobalt and nickel can be effectively masked with potassium cyanide. Beer's law is obeyed up to 2 ppm of manganese. The molar absorptivity of the manganese—PAN chelate found was 4.4 × 10⁴ l. mole ⁻¹. cm⁻¹ at 562 nm. The overall stability constant of Mn(PAN)₂ in 0.4% Triton X-100 medium is 10^16.8.     

Mass spectrometric investigation of copper chelates with 1-(2-pyridylazo)-2-naphthol

The mass spectra of copper chelates of 1-(2-pyridylazo)-2-naphthol, HX, prepared by different methods, are discussed. Peaks due to Cu(2)X(2)(+), CuX(2)(+) and CuXCl(+) have been positively identified and all copper-containing species have the expected isotopic ratios. The significance of probe temperature and impurities are discussed and it is concluded that the spectra are more in accordance with the known chemical facts than those reported earlier by Betteridge and John.     

Spectrophotometric determination of rare earth metals with 1-(2-pyridylazo)-2-naphthol

1-(2-Pyridylazo)-2-naphthol (PAN) reacts very sensitively with rare earth metals to form a deep red precipitate in alkaline solution; this can be extracted with ether, except in the case of lanthanum, cerium and scandium. Absorption maxima occur at 530 and 560 mμ. Traces of rare earth metals may be determined in the presence of many foreign metals.     

微乳液--1-(2-吡啶偶氮)-2-萘酚体系测定Co(Ⅱ)

The spectrohpotometric determination of Co(Ⅱ) was studied with 1-( 2 -pyridylazo)-2-naphthol in the sodium dodecyl sulphate/n-heptane/water micr oemulsion medium.The apparent molar absorptivity is 1.84×10⁴ L^.mol -1^.cm^-1 at 575 nm.Beer's law is obeyed in the range of 0～ 50 μg/25 mL for Co(Ⅱ).     

Sensitive spectrophotometric determination of La(III) with 1-(2-pyridylazo)-2-naphthol

A simple and sensitive method for spectrophotometric determination of lanthanum has been developed. At pH 9.6, in presence of 50% ethanol, lanthanum reacts with 1-(-2-pyridylazo)-2-naphthol (PAN) to form a red complex which has two absorption maxima, at 545 and 510 nm. The molar absorptivity at 545 nm is 0.55 × 10⁴ liters · mol^?1 cm^?1. On the other hand, lanthanum reacts with PAN in pure ethanol to form a red complex at 530 nm, with high molar absorptivity (8 × 10⁴ liters · mol^?1 cm^?1).     

Analytical properties of 1-(2-pyridylazo)-2-naphthol immobilized on a polymethacrylate matrix

The adsorption of 1-(2-pyridylazo)-2-naphthol (PAN) with a polymethacrylate matrix from a water-ethanol solution is studied. It is shown that PAN immobilized on a polymethacrylate matrix retains its analytical properties.     

Spectrophotometric determination of traces of gallium and indium with 1-(2-pyridylazo)-2-naphthol

1-(2-Pyridylazo)-2-naphthol (PAN) reacts with either gallium or indium at pH 5–6 giving a red complex in an aqueous medium in the presence of N.N-dimethyl-formamide. The maximum absorption of both PAN complexes of gallium and indium in an aqueous solution is at 545 mμ. The gallium-PAN complex shows a characteristic enhancement of color by addition of small amounts of ethers. Based on this selective enhancement reaction, gallium can be determined in the presence of other metals without separation. The results of determining gallium and indium in the presence of each other are reported. Both gallium and indium form M₂(PAN)₃; but in the presence of certain organic solvents, a different gallium complex, Ga(PAN)₅, and the same indium complex, In₂(PAN)₃, are formed. The reaction of PAN with cadmium can be masked by iodide; an example of determining indium in the presence of cadmium is given. The PAN method has a sensitivity of 0.003 μg/cm² for gallium and 0.005μg/cm² for indium and an absorptivity of 24,900 for the Ga-PAN complex and of 24,500 for the In-PAN complex, respectively. The methods have been successfully applied to the determination of both gallium and indium in germanium thin films.     

Extraction studies on the group VB–VIIB and VIII elements using 1-(2-pyridylazo)-2-naphthol as chelating reagent

Extraction behaviour of the chelates of group VB–VIIB and VIII elements using 1-(2-pyridylazo)-2-naphthol (PAN) has been studied as a function of pH. Studies have been made to back-extract the metal ions from the organic phase into the aqueous solution containing the optimum concentration of KCN and HClO₄ and buffers of appropriate pH. The masking agents such as citrate, cyanide, thiosulphate, fluoride and thiourea were used to achieve more specific separations. The studies indicate the potentiality of PAN as a useful solvent extracting reagent in devising group chemical separation procedures for activation analysis.     

Liquid chromatography of palladium and non-ferrous metal chelates with 1-(2-pyridylazo)-2-naphthol

1-(2-Pyridylazo)-2-naphthol has been used for extraction concentration of palladium, copper, cobalt and nickel from aqueous solutions and subsequent separation of the chelates obtained, by means of high-pressure liquid chromatography. A technique for determining microamounts of palladium in aqueous solutions in the presence of 100-fold ratio of copper and 80-fold ratio of cobalt has been developed.