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     

Complex formation studies on Ho(III) and Lu(III) with 1-(2-pyridylazo)-2-naphthol (PAN) in alcohol-water solutions

The formation ofPAN complexes in the systemsLn(III)—PAN—alcohol-water (where:Ln(III)=Ho, Lu and alcohol=ethanol,n-propanol,iso-propanol) was investigated by a spectrophotometric method. Equilibrium constants for the reactionLn ³⁺ + HLLnL ²⁺ + H⁺ (HL=PAN) and stability constants of complexesLnL ²⁺ were calculated.

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Untersuchungen zur Komplexbildung von Ho(III) und Lu(III) mit 1-(2-Pyridylazo)-2-naphthol (PAN) in alkoholisch-;wä\rigen Lösungen

Zusammenfassung Die Bildung der Komplexe vonPAN in den SystemenLn(III)—PAN—Alkohol-Wasser (Ln(III)=Ho, Lu; Alkohol=Ethanol,n-Propanol,iso-Propanol) wurde mit einer spektrophotometrischen Methode untersucht. Die Gleichgewichtskonstanten der ReaktionenLn ³⁺ + HLLnL ²⁺ + H⁺ (HL==PAN) und die Stabilitätskonstanten der KomplexeLnL ²⁺ wurden berechnet.

     

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.     

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 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).     

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 study of complex formations between 1-(2-pyridylazo)-2-naphthol (PAN) and some metal ions in organic solvents and the determination of thermodynamic parameters

The complexation reactions between Ni(2+), Co(2+) and Zn(2+) metal ions with PAN in methanol (MeOH), acetonitrile (AN) and dimethyl sulfoxide (DMSO) were studied using a spectrophotometric method. The stability constants of the resulting complexes were determined from computer fitting absorbance mole-ratio data. The results revealed that the stability constants of complexes are varying in order of Ni(2+)相似文献   

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.     

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.     

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).     

Solvent extraction of rare earth metal ions with 1-(2-pyridylazo)-2-naphthol (PAN)

The formation of the Tm(III) complex with 1-(2-pyridylazo)-2-naphthol (PAN or HL) in aqueous-methanol mixtures (50 and 75%v/v) was studied by a spectrophotometric method. The equilibrium constant for the complexing reaction and the stability constant of the complex TmL ²⁺ were calculated. The solvent extraction of Tm(III) byPAN in carbon tetrachloride from aqueous and aqueous-methanol phase was investigated. The extraction equilibrium constants and two-phase stability constants for the TmL ₃ and the TmL ₃(MeOH)₃ complexes were evaluated. It was confirmed that the addition of methanol to the aqueous phase (above 25%v/v) causes a synergistic effect.

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Extraktion von Ionen der Seltenerdmetalle mit 1-(2-Pyridylazo)-2-naphthol (PAN), 5. Mitt.: Komplexbildung und Gleichgewichtsverteilung von Thulium (III) mitPAN

Zusammenfassung Die Bildung des Komplexes von Tm(III) mit 1-(2-Pyridylazo)-2-naphthol (PAN oder HL) in Wasser-Methanol Mischungen (50 und 75%v/v) wurde mit einer spektrophotometrischen Methode untersucht. Die Gleichgewichtskonstante für die Reaktion der Komplexbildung und die Stabilitätskonstante des Komplexes TmL ²⁺ wurden berechnet. Die Extraktion von Tm(III) mittelsPAN in Kohlenstofftetrachlorid aus Wasser oder Wasser-Methanol wurde untersucht. Die Werte der Extraktionsgleichgewichtskonstante sowie der zweiphasigen Beständigkeitskonstante für die Komplexe TmL ₃ und TmL ₃(MeOH)₃ wurden berechnet. Es wurde festgestellt, daß die Zugabe von Methanol zur wäßrigen Phase (25%v/v) einen synergistischen Effekt hat.

     

Solvent extraction of rare earth metal ions with 1-(2-pyridylazo)-2-naphthol (PAN)

The solvent extraction of Yb(III) and Ho(III) by 1-(2-pyridylazo)-2-naphthol (PAN or HL) in carbon tetrachloride from aqueous-methanol phase has been studied as a function ofpH ^× and the concentration ofPAN or methanol (MeOH) in the organic phase. When the aqueous phase contains above ～25%v/v of methanol the synergistic effect was increased. The equation for the extraction reaction has been suggested as: $$\begin{gathered} Ln(H_2 0)_{m(p)}^{3 + } + 3 HL_{(o)} + t MeOH_{(o)} \mathop \rightleftharpoons \limits^{K_{ex} } \hfill \\ LnL_3 (MeOH)_{t(o)} + 3 H_{(p)}^ + + m H_2 0 \hfill \\ \end{gathered} $$ where:Ln ³⁺=Yb, Ho; $$\begin{gathered} t = 3 for C_{MeOH in.} \varepsilon \left( { \sim 25 - 50} \right)\% {\upsilon \mathord{\left/ {\vphantom {\upsilon \upsilon }} \right. \kern-\nulldelimiterspace} \upsilon }; \hfill \\ t = 0 for C_{MeOH in.} \varepsilon \left( { \sim 5 - 25} \right)\% {\upsilon \mathord{\left/ {\vphantom {\upsilon \upsilon }} \right. \kern-\nulldelimiterspace} \upsilon } \hfill \\ \end{gathered} $$ . The extraction equilibrium constants (K _ex ) and the two-phase stability constants (β ₃ ^× ) for theLnL ₃(MeOH)₃ complexes have been evaluated.     

Solvent extraction of rare earth metal ions with 1-(2-pyridylazo)-2-naphthol (PAN)

Extraction of lutetium(III) and erbium(III) with 1-(2-pyridylazo)-2-naphthol (PAN or HL) in carbon tetrachloride from aqueous solutions was examined. The composition of the complex extracted was determined and it was found that the extraction process can be described by the following equation (Ln ³⁺=Lu, Er): $$Ln(H_2 O)_m^{3 + } + 3 HL_{(0)} \mathop \rightleftharpoons \limits^{K_{ex} } LnL_{3(0)} + 3 H^ + + mH_2 O$$ The extraction constants (K _ex ) and two-phase stability constants (β ₃ ^x ) forLnL ₃ complexes have been evaluated.     

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.     

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.     

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).     

Solvent extraction of certain rare earth metal ions with 1-(2-pyridylazo)-2-naphthol (PAN)

The solvent extraction of Yb(III) by 1-(2-pyridylazo)-2-naphthol (PAN or HL) in carbon tetrachloride from aqueous—ethanol phase has been investigated as a function of thepH ^X of the polar phase and the concentrations ofPAN or ethanol (EtOH) in the organic phase. It was confirmed that the addition of ethanol to the aqueous phase causes an increase of the Yb(III) distribution coefficient. The equation for the extraction reaction has been suggested as: $$Yb(H_2 O)_{m(^p )}^{3 + } + 3H L_{(o)} + t Et OH_{(o)} \rightleftharpoons Yb L_3 \left( {EtOH} \right)_{t(o)} + 3H_{(^p )}^ + + mH_2 O$$ wheret changes from 0 to 3. The extraction equilibrium constant (K _ex ) and two-phase stability constants (β ₃ ^× ) for the YbL ₃ (EtOH)₃ complex have been evaluated. The formation of solvates YbL ₃ (EtOH) _t is probably the main reason of the synergistic effect which was observed.     

Simultaneous spectrophotometric determination of Zinc(II) and Nickel(II) with 1-(2-pyridylazo)-2-naphthol

A new procedure for the simultaneous spectrophotometric determination of Zn(II) and Ni(II) with 1-(2-pyridylazo)-2-naphthol as chromogenic reagent has been developed. It is based on resolution of the mixed spectrum over the wavelength range 530–590 nm by applying a least-squares fitting program to standard spectra from each component. The spectra are recorded at an apparent pH of 5.0, provided by an acetate buffer in a mixed 6040 v/v 2-ethoxyethanol/water medium. The relative standard deviations for determination of 13.7 g of Ni and 31.0 g of Zn were 1.9 and 1.0%, respectively (8 replications). The method has been applied to the analysis of iron surfaces coated with a Zn-Ni alloy. The results are compared with those obtained by atomic-absorption spectrophotometry.