Spectrophotometric determination of palladium using arsenazo I

A new simple rapid method for the spectrophotometric determination of palladium using arsenazo I is given. The optimum conditions favoring the formation of the complex are extensively investigated; the molecular structure was found to be 1:1. Beer's law is obeyed for the ranges 1.0–10.6 or 0.64–6.39 ppm of Pd.     

Extraction—spectrophotometric determination of palladium with n-butylxanthate

Palladium (6–180 nmol) is extracted quantitatively with potassium n-butyl-xanthate into benzene from an aqueous phase containing EDTA, and determined spectrophotometrically at 290 nm. The molar absorptivity of the complex is 7.5 × 10⁴ dm³ mol^-1 cm^-1.     

Extraction and flame spectrophotometric determination of palladium and rhodium

Solvent extraction methods involving toluene, chloroform, 4-methyl-2-pentanone and pentyl acetate were studied for palladium and rhodium chelates. The palladiurn-salicylaldoxime chelate was extracted quantitatively into 4-methyl-2-pentanone at pH 3. The rhodium-diethyldithiocarbamate chelate was completely extracted into 4-methyl-2-pentanone at pH 8. The optimum combustion conditions for each of the organic extracts were then studied. The position of maximum emission intensity in the flame mantle was determined for each chelate and solvent system ; readings were taken at 363.5 mμ for palladium, and 369.2 mμ for rhodium. For palla-dium, when 4-methyl-2-pentanone was used instead of water as solvent, the emission intensity increased 21-fold. For rhodium, this kctone increased the sensitivity 27 times compared with water. A method is suggested for the separation and determination of palladium and rhodium in the same sample.     

Extraction of palladium(II) by the hexachloroderivate of cobalt dicarbolide from nitric acid medium

Liquid—liquid extraction of divalent palladium by solutions of the hexachloroderivate of cobalt dicarbolide (HBCl₆) in the mixture of solvents (30 v/v % nitrobenzene+20 v/v % n-dodecane +50 v/v/ % toluene) from nitric acid medium has been studied. Besides HBCl₆ the organic phase contained also 2,2′-dipyridyl (dipy). The yield of palladium extraction from 0.5M HNO₃ is greater than 99.0%. The species extracted into the organic phase corresponds to the formula [Pd(dipy)₂] (BCl₆)₂.     

Analytical application of arsenazo III to the spectrophotometric determination of palladium: Preliminary investigation of the complex formation in the arsenazo III-Pd (II)--H2O system

The reaction of arsenazo III with palladium(II) was investigated. Complex species of types M₂L and ML are formed at pH 2–4; the complex M₂L shows a very sharp maximum at 630 nm while the ML species shows maximum absorption at 620 nm. The molar absorptivities of the complexes are 4.2(±0.1) · 10⁴ and 1.6(±0.2) · 10⁴ respectively. The complex ML conforms to Beer's law at 620 nm in the range 10–250 μg Pd(II)/50 ml. The sensitivity of the reaction of Pd(II) with arsenazo III is about the same as that of a new reagent, palladiazo, but the latter is more selective for Pd(II). Serious interferences might be caused by UO₂²⁺, U⁴⁺, Th⁴⁺, Cu²⁺, Ni²⁺, Co²⁺, Y³⁺ and the rare-earth elements.     

Separation and spectrophotometric determination of uranium (VI) by extraction with arsenazo III and zephiramine

Summary Microgram quantities of uranium(VI) can be determined at 655 nm after separation by chloroform extraction of its Arsenazo III complex with Zephiramine. The extracted uranium can be back-extracted with an aqueous solution of ammonium carbonate. Uranium can be separated from aluminium, iron(II), and some other elements. Probably the same species, i. e., the ion association compound between the uranium (VI)-Arsenazo III complex and Zephiramine are involved during the extraction and the froth flotation.

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Zusammenfassung Mikrogrammengen Uran(VI) lassen sich nach Chloroformextraktion seines Arsenazo-III-Komplexes mit Zephiramin bei 655 nm messen. Das extrahierte Uran kann man mit wäßriger Ammoniumcarbonatlösung rück-extrahieren. Von Aluminium, Eisen(II) und einigen anderen Elementen kann es so getrennt werden. Wahrscheinlich handelt es sich bei der Extraktion und der Schaumflotation um die gleiche Ionenassoziatverbindung des Uran (VI)-Arsenazo-III-Komplexes mit Zephiramin.

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Presented at the 24th Annual Meeting of the Japan Society for Analytical Chemistry, Sapporo, October, 1975.     

Solid phase extraction of zirconium as arsenazo(III) complex on agar and spectrophotometric determination

A new solid phase extraction method for the separation and determination of zirconium using agar as an adsorbent is described. The method is based on the adsorption of zirconium as arsenazo(III) complex on agar in a mini-column, elution with sulfuric acid-acetone mixture and determination by spectrophotometry. The effect of different parameters such as pH, concentration of the reagent, eluting reagent, and volume of the sample, amount of the adsorbent and interfering ions was investigated. The calibration graph was linear in the range of 5?C300 ng ml^?1 of zirconium under optimum conditions. The limit of detection based on 3S_b was 1.3 ng ml^?1 and the relative standard deviation (R.S.D) for ten replicate measurements of 15 and 200 ng ml^?1 of zirconium was 3.7 and 1.8%, respectively. The method was applied to the determination of zirconium in water and soil samples.     

Extraction of palladium from nitric acid medium by commercial resins with phosphinic acid,methylene thiol and isothiouronium moieties attached to polystyrene-divinylbenzene

Summary Commercially available polystyrene-divinylbenzene (PS-DVB) resins functionalized with isothiouronium (Tulsion CH-95), phosphinic acid (Tulsion CH-96) and methylene thiol (Tulsion CH-97) moieties have been used for separating palladium from nitric acid medium. Extraction of palladium has been studied as a function of time, concentration of nitric acid and palladium. The distribution coefficients (K_d, ml/g) of palladium on sulfur based resins (Tulsion CH-95 and Tulsion CH-97) are higher (5000-10⁴ml/g in 0.1M nitric acid) than on Tulsion CH-96 resin and decrease with increasing concentration of nitric acid. The initial rate of extraction of palladium by Tulsion CH-95 and Tulsion CH-97 resins was very rapid and the time required for the establishment of equilibrium was a function of palladium concentration in the aqueous phase. The rate data could be fitted by a second order rate equation and the magnitude of rate constant for the extraction of palladium by these resins (~10²M^-1. min^-1) decreased in the order of: Tulsion CH-95 > Tulsion CH-97 > Tulsion CH-96. The extraction isotherms of Tulsion CH-95 were fitted by Langmuir adsorption model and the coefficients were obtained by regression. The extraction capacity of palladium on Tulsion CH-95 was found to be ~20 mg/g at 3M nitric acid. Column experiments have been conducted and the data were fitted using Thomas model. A column utilization of 75% was achieved for the extraction of palladium by Tulsion CH-95 resin.     

Indirect spectrophotometric determination of palladium using 1,10-phenanthroline as reagent

Summary The spectrophotometric method for the determination of palladium is based upon the addition of a standard 1,10-phenanthroline solution to precipitate Pd(phen)Cl₂ and the determination of 1,10-phenanthroline concentration of the supernatant solution. The absorbancy readings were made in the absorption maximum at about 271 nm, in the concentration range of 10^–6 to 10^–5M 1,10-phenanthroline in 0.1 M hydrochloric acid and 0.1% hydroxylamine hydrochloride. For the phenanthroline system Beer's law is valid. Ions which either form with phenanthroline very strong complexes or interfere with the spectrophotometric determination of 1,10-phenanthroline must be absent. The method is simple, rapid, accurate and applicable to the macro and micro-determination of palladium in different systems. Standard deviation was found to be 0.085 ppm (in pure Pd solutions).

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Indirekte spektrophotometrische Bestimmung von Palladium mit 1,10-Phenanthrolin

Zusammenfassung Das Verfahren beruht auf der Fällung von Pd(phen)Cl₂ durch Zusatz einer bestimmten Menge Standard-1,10-Phenanthrolinlösung und spektrophotometrischer Bestimmung des Überschusses.Die Messungen werden bei dem Absorptionsmaximum bei etwa 271 nm und einer Konzentration von 10^–6M bis 10^–5M 1,10-Phenanthrolin in 0,1 M HCl und 0,1% Hydroxylaminhydrochlorid enthaltender Lösung durchgeführt. Das 1,10-Phenanthrolinsystem folgt dem Beerschen Gesetz. Ionen, die entweder mit 1,10-Phenanthrolin starke Komplexe bilden oder die spektrophotometrische Bestimmung von 1,10-Phenanthrolin beeinflussen, müssen abwesend sein. Die Methode ist einfach, rasch und genau und kann für Mikro- und Makrobestimmungen in verschiedenen Systemen angewendet werden. Die Standardabweichung beträgt 0,085 ppm (in reinen Pd-Lösungen).

     

Extraction and spectrophotometric determination of thallium(III) with thiothenoyltrifluoroacetone

A procedure is described for the extractive photometric determination of thallium(III) with thiothenoyltrifluoroacetone in carbon tetrachloride. Thallium(III) is extracted quantitatively at pH 4-5 and the bright yellow extract obeys Beer's law over the Tl(III) concentration range 2.5-17.5 mug/ml, at 440 nm. Thallium(III) can be determined in the presence of a large number of cations and anions.     

Comparative study of the masking effect of various complexans in the spectrophotometric determination of uranium with arsenazo III and chlorophosphonazo III

Results are presented for the masking of 35 elements with the complexans DTPA, EGTA and TTHA in the spectrophotometric determination of uranium(VI) with Arsenazo III at pH 1.8 +/- 0.2 and with Chlorophosphonazo III at pH 1.1 +/- 0.2. The complexans EDTA and DCTA were found to be less suitable because at low pH they tended to precipitate. DTPA is shown to be especially attractive for masking other elements in the determination of uranium(VI) at low pH.     

Extraction spectrophotometric determination of cobalt and nickel using ethylthioxanthate

A spectrophotometric method for the determination of cobalt and nickel using a new reagent sodium ethylthioxanthate has been described. The yellow-colored cobalt complex and red-colored nickel complex have been extracted quantitatively using carbon tetrachloride in the pH ranges 4.0–11 and 4.0–6.7, respectively. The colors of these complexes are stable and absorbances have been measured at 389 nm for cobalt and 495 nm for the nickel complexes. Few ions interfere but the method has been applied successfully for the determination of these metal ions in various complex materials.     

Extraction behavior of U(IV) from nitric acid medium using di-isodecyl phosphoric acid dissolved in dodecane

Solvent extraction of U(VI) with di-isodecyl phosphoric acid (DIDPA)/dodecane from nitric acid medium has been investigated for a wide range of experimental conditions. Effect of various parameters including nitric acid concentration, DIDPA concentration, temperature, stripping agents, and other impurities like rear earths, transition metal ion, boron, aluminum ion on U(VI) extraction has been studied. The species extracted in the organic phase is found to be UO₂(NO₃)(HA₂)·H₂A₂ at lower acidity (<3.0 M HNO₃). Increase in temperature lead to the decrease in extraction with the enthalpy change by ∆H = −16.27 kJ/mol. Enhancement in extraction of U(VI) from nitric acid medium was observed with the mixture of DIDPA and tri butyl phosphate (TBP). The stripping of U(VI) from organic phase (DIDPA–U(VI)/dodecane) with various reagents followed the order: 4 M H₂SO₄ > 5% (NH₄)₂CO₃ > 8 M HCl > 8 M HNO₃ > Water. High separation factors between U(VI) and impurities suggested that the use of DIDPA for purification of uranium from multi elements bearing solution.     

Extraction of nitric acid,technetium and palladium by bidentate carbamoylphosphonates

The extraction of HNO₃, TcO ₄ ^? , and Pd by solutions of dibutyl N,N-diethylcarbamoylmethylenephosphonate (DBDECMP) and dibutyl N,N-diethylcarbamoylphosphonate (DBDECP) in CCl₄ has been studied. At low aqueous acidities, HNO₃ is extracted by both extractants (S) as HNO₃·S and HNO₃·S₂, at >1M HNO₃ only HNO₃·S is formed. The distribution of TcO ₄ ^? and Pd(II) is nearly independent of HNO₃ concentration. A second power dependence on extractant concentration was found for the extraction of Pd(II) by DBDECMP and TcO ₄ ^? by DBDECP, and a 4th power dependence for TcO ₄ ^? -DBDECMP.     

Efficient extraction of Rh(III) from nitric acid medium using a hydrophobic ionic liquid

Rhodium(III) has been successfully extracted from an aqueous nitric acid solution using a hydrophobic ammonium based ionic liquid and CMPO or TODGA as extractant. This result has significant potential for the recovery of rhodium from spent nuclear fuel and thereby increasing the worldwide supply of this rare metal.     

Separation of antimony(III) with iodide and dithizone by sorption on polyurethane foam from sulphuric acid medium for its spectrophotometric determination in glasses

A method for quantitative separation of antimony(III) by sorption on polyether based polyurethane foam and its spectrophotometric determination has been described. The method involves formation of a pink-red complex of antimony(III) with iodide (0.045M) and dithizone (2.3 x 10(-5)M) in 0.25-0.75M H(2)SO(4) medium, sorption of the complex on polyurethane foam (within 45 min) at room temperature followed by its elution with acidified acetone (acetone containing 0.008% H(2)SO(4)) and spectrophotometric measurement at 507.2 nm ( = 2.56 x 10(4) l mol cm). The method obeys Beer's law from 0.1 to 6.0 mug antimony(III). Tolerance limits of other ions are Co (100 mug), Ni (100 mug), Fe (10 mug), Cu (0.5 mug), Sn (20 mug), Zn (100 mug), As (100 mug), Mn (200 mug), Pb (50 mug), Ti (100 mug), V (50 mug), etc. Interference by iron and copper have been eliminated by treating with KOH prior to the extraction of antimony. The method has been standardized with glass samples spiked with known amounts of antimony and applied to the determination of antimony in various glasses.     

Extraction of palladium with thiacalix[4]arenes from nitric acid nitrate-nitrite solutions

Calix[4]arene 1, thiacalix[4]arenes 2(LH₄), and calix[4]arenethioether 3 were compared in palladium extraction from nitric acid solutions; D _Pd for 2 was shown to be 2?C3 orders of magnitude larger than for 1 at pH > 3 (comparable with 3) because of cation-exchange and coordination extraction of palladium. It was shown by extraction methods and IR spectroscopy that thiacalixarenes 2 extract complex species [Pd _n L _m H_{4 ? 2n} ] (m = 1, n = 1 and 2) and [(PdA₂) _n L _m H₄] (A = m = 1, n = 1?C4) from nitric acid solutions at pH 3. Extraction constants for these palladium species that satisfactorily describe experimental data were calculated. As distinct from 3, thiacalixarenes 2 are promising for the combined extraction of palladium and silver from alkaline solutions and the selective extraction of fission palladium from nitric acid solutions. Phosphorylated at the upper rim thiacalixarenes 2 can be considered as bifunctional extractants for the separation of fission radionuclides.     

Extraction of gold(III) from low-grade ores with amidines followed by its spectrophotometric determination with methylene blue

A procedure is described in which gold(III) is quantitatively extracted with an amidine into chloroform over the acidity range pH 3.0–11.0 M HCl, followed by its selective spectrophotometric determination by interaction of the extract with methylene blue in the pH range 3.0–9.0. The molar absorptivity of the coloured complex formed by extraction with ten different amidines and methylene blue reaction lie in the range 1.1 × 10⁴?6.5 × 10⁴ 1 mol^?1 cm^?1 at λ_max (650 nm) in chloroform. The simplest compound, N, N′-diphenylbenzamidine, was chosen for detailed study. The limit of detection is 5 μg Au l^?1. The method is free from interferences from the metals that are generally associated with gold. The method is simple, reproducible and applicable to the accurate recovery of gold from low-grade ores containing the metal at levels of > 1.5 μg g^?1.