Flame atomic absorption spectrometric determination of trace amounts of palladium,gold and nickel after cloud point extraction

In this article, a sensitive cloud point extraction procedure for the preconcentration of trace amounts of palladium, gold and nickel prior to their determination by flame atomic absorption spectrometry has been developed. The cloud point extraction method is based on the complexation of Pd(II), Au(II), and Ni(II) ions with 1-(2-pyridylazo)-2-naphthol and entrapping in non-ionic surfactant Triton X-114. The main factors affecting cloud point extraction efficiency, such as pH of sample solution, concentration of 1-(2-pyridylazo)-2-naphthol and Triton X-114, equilibration temperature and time, were investigated in detail. Under the optimized conditions, calibration curves were constructed for the determination of palladium, gold and nickel according to the general procedure. Linearity was maintained from 0.01 to 1.0 μg/mL for palladium, 10.0 μg/mL to 1.5 μg/mL for gold, and 10.0 μg/mL to 0.5 μg/mL for nickel. Detection limits based on three times the standard deviation of the blank divided by the slope of analytical curve (3Sb/m) for Pd(II), Au(III), and Ni(11) ions were 3.4, 3.9, and 2.4 μg/mL, respectively. Seven replicate determination of a mixture of 0.5 μg/mL palladium and gold and 0.2 μg/mL nickel gave a mean absorbance of 0.174, 0.150, and 0.201 with relative standard deviation ±1.5, ±1.3, and ±1.8%, respectively. The high efficiency of cloud point extraction to carry out the determination of analytes in complex matrices was demonstrated. The proposed method has been applied for determination of trace amount of palladium, gold and nickel in certified reference material and water samples with satisfactory results.     

Determination of gold,palladium and copper by flame atomic absorption spectrometry after preconcentration on silica gel modified with 3-(2-aminoethylamino)propyl group

A preconcentration method of gold, palladium and copper based on the sorption of Au (III), Pd (II) and Cu (II) ions on a column packed with 3-(2-aminoethylamino)propyl bonded silica gel is described. The modified silica gel was synthesized and characterized by FT-IR and C, H, N elemental analysis. At column preconcentration, the effects of parameters such as pH, volume, flow rate, matrix constituents of solutions and type of eluent on preconcentration of gold, palladium and copper were studied. The recoveries of Au (III), Pd (II) and Cu (II) were 98.93±0.51, 98.81±0.36 and 99.21±0.42 % at 95 % confidence level, respectively. The detection limits (δ) of the elements were 0.032, 0.016 and 0.012 μg ml⁻¹, respectively. The preconcentration method was applied for determination of gold and palladium in certified reference material SARM 7B and copper in river and synthetic seawater by FAAS. Gold, palladium and copper were determined with relative error lower than 10 %.     

Simultaneous First Derivative Spectrophotometric Determination of Palladium and Nickel Using 2-(2-Thiazolylazo)-5-Dimethylaminobenzoic Acid as an Analytical Reagent

 A simple, rapid, selective, sensitive and economical method has been developed for the simultaneous determination of trace amounts of palladium and nickel in aqueous methanolic medium using 2-(2-thiazolylazo)-5-dimethylam inobenzoic acid as an analytical reagent by first derivative spectrophotometr y. Palladium is determined by measuring base to peak distance at λ=695.0 nm while nickel is estimated by zero crossing method in the mixture. The linearity is maintained between 0.12–1.75 μg mL⁻¹ for palladium and 0.07–1.60 μg mL⁻¹ for nickel in the pH range 2.8–7.2 and 3.4–8.8 respectively. Seven replicate determinations of 1.0 μ g mL⁻¹ of palladium and 0.8 μg mL⁻¹ of nickel in a mixture give a mean signal height of 0.391 for Pd and 0.541 for Ni with relative standard deviations of 0.9% and 1.2%, respectively. The sensitivity of the proposed method is 0.391 (dA/dλ)/(μg mL⁻¹) for palladium and 0.685 (dA/dλ)/(μg mL⁻¹) for nickel. Various parameters have been optimised for the simultaneous determination of palladium and nickel in various complex samples. Received March 30, 1999. Revision November 25, 1999.     

FI spectrophotometric determination of Pd with DBOK-chlorophosphonazo

A flow injection method was developed for the determination of palladium, based on the reaction of palladium with DBOK-chlorophosphonazo with a detection limit of 0.07 μg/mL and a linear calibration range from 0.1 to 3.2 μg/mL of palladium. The reaction product has a maximum absorption at 630 nm. The method was applied to determine Pd²⁺ in catalysts and in anode mud samples. The relative error is less than 3% and the recovery of palladium is in the range 95% to 105% Received: 27 April 1998 / Revised: 24 August 1998 / Accepted: 26 August 1998     

Catalytic kinetic spectrophotometric determination of trace amounts of palladium with dahlia violet after separation and preconcentration on sulphydryl dextran gel

A sensitive and selective kinetic catalytic spectrophotometric method has been described for the determination of trace amounts of palladium(II). The method is based on the catalytic effects of palladium(II) on the reduction reactions of Dahlia Violet with sodium dihydrogen hypophosphite (NaH₂PO₂) in a sulfuric acid medium. Under optimal conditions, trace amounts of palladium(II) can be determined. A good linear range has been obtained in the concentration range of Pd(II) over 0.001–0.028 μg/mL with a detection limit of 5.9 × 10⁻¹⁰ g/mL. The method has been successfully applied to the determination of palladium(II) in ore and soil samples. The relative standard deviation was less than 5.0% (n = 11). The coexisting ions were eliminated by preconcentration and separation on sulphydryl dextran gel with satisfactory results. The text was submitted by the authors in English.     

FI spectrophotometric determination of Pd with DBOK-chlorophosphonazo

A flow injection method was developed for the determination of palladium, based on the reaction of palladium with DBOK-chlorophosphonazo with a detection limit of 0.07 μg/mL and a linear calibration range from 0.1 to 3.2 μg/mL of palladium. The reaction product has a maximum absorption at 630 nm. The method was applied to determine Pd²⁺ in catalysts and in anode mud samples. The relative error is less than 3% and the recovery of palladium is in the range 95% to 105% Received: 27 April 1998 / Revised: 24 August 1998 / Accepted: 26 August 1998     

Modified analcime loaded with zincon as a useful material for the separation and preconcentration of trace palladium and its determination by third-derivative spectrophotometry

This work assesses the potential of natural analcime zeolite as a sorbent for the preconcentration of palladium. Palladium is quantitatively retained on modified analcime zeolite loaded with zincon using the column method in the pH range from 2.5 to 3.5 at a flow rate of 1 mL/min. The palladium complex was removed from the column with 5.0 mL of dimethylsulfoxide (DMSO) and determined by third-derivative spectrophotometry. The detection limit is 0.03 μg/mL (signal-to-noise ratio = 3) in the final solution. Since it is possible to retain 0.15 μg of palladium from 600 mL of solution passing through the column, elution with 5.0 mL of DMSO gives a detection limit of 0.25 ng/mL for palladium in the initial aqueous solution. The calibration curve is linear over the range 0.1 to 5.0 μg/mL of palladium(II) in the final solution with a correlation coefficient of 0.9996. Seven replicated determinations of 5.0 μg of palladium in 5.0 mL dimethylsulfoxide gave a mean d ³ A/dλ³ (peak-to-peak signal between λ₂ = 625 and λ₁ = 654 nm) of 0.64 with a relative standard deviation of 1.2%. The sensitivity of the method (d ³ A/dλ³) is 0.5843 mL/μg of palladium(II) from the slope of the calibration curve. The interference of a large number of anions and cations has been studied and the optimized conditions developed were utilized for the determination of trace palladium in various synthetic and water samples. The text was submitted by the authors in English.     

Determination of palladium by flame atomic absorption spectrophotometry after separation by extraction of its nioximate into molten naphthalene

Summary A selective analytical method has been developed for the determination of palladium in synthetic mixtures by atomic absorption spectrophotometry. Nioxime reacts with palladium(II) to form a thermally stable complex which is quantitatively extracted into molten naphthalene in the pH range of 1.0–6.0. The extracted solid is separated from aqueous solution by filtration and dissolved in 10%n-butylamine solution of dimethylformamide. The palladium content in this solution is measured at 244.7 nm by AAS with an air-acetylene flame. Beer's law is obeyed in the concentration range of 7–120g of palladium in 10 ml of DMF solution. The sensitivity is 0.13g/ml Pd for 1% absorption. For ten replicate analyses of 60g of palladium the relative standard deviation was 0.5%.

---

Bestimmung von Palladium durch AAS nach Extraktion seines Nioximates in geschmolzenes Naphthalin

Zusammenfassung Ein selektives Analyseverfahren zur Bestimmung von Palladium in synthetischen Gemischen durch AAS wurde ausgearbeitet. Nioxim reagiert mit Pd(II) unter Bildung eines stabilen Komplexes, der bei pH 1,0–6,0 quantitativ in geschmolzenes Naphthalin extrahiert wird. Der feste Extrakt wird von der wäßrigen Lösung abfiltriert und in der 10% igen Lösung von Dimethylformamid inn-Butylamin gelöst. Deren Pd-Gehalt wird bei 244,7 nm durch AAS mit einer Acetylen-Luftflamme bestimmt. Das Beersche Gesetz gilt für 7–120g Pd in 10 ml DMF. Die Empfindlichkeit beträgt 0,13g/ml Pd für 1% Absorption. Für 10 wiederholte Analysen von 60g Pd beträgt die Standard-Abweichung 0,5%.

     

Synthesis,spectral and thermal studies on pyrazolatebridged palladium(II) coordination polymers

Synthesis, spectroscopic characterization and thermal behavior of pyrazolate-bridged palladium complexes [Pd(μ-Pz)₂]_n (1), [Pd(μ-mPz)₂]_n (2), [Pd(μ-dmPz)₂]_n (3), [Pd(μ-IPz)₂]_n (4) {pyrazolate (Pz^–), 4-methylpyrazolate (mPz^–), 3,5-dimethylpyrazolate (dmPz^–), 4-iodopyrazolate (IPz^–)} have been described in this work. The exobidentate coordination mode of pyrazolato ligands in 1–4 was inferred on basis of IR spectroscopic evidences. TG investigations indicated that the introduction of substituents at the 4 position in the pyrazolyl moiety into coordination polymers do not affect significantly their thermal stability, whereas at the 3 and 5 position reduced the stability of the main chain. Metal palladium was the final product of the thermal decompositions, which was identified by X-ray powder diffraction.     

Evaluation of nonlinear modeling based on artificial neural networks for the spectrophotometric determination of Pd(II) with CPA-mK

A new method is proposed for the spectrophotometric determination of Pd(II), based on the reaction of Pd(II) with 2-(4-chloro-2-phosphonophenylazo)-7-(3-carboxyphenylazo)-1,8-dihydroxynaphthalene-3,6-disulfonic acid(CPA-mK) in sulfuric acid without heating. Beer’s law is obeyed for 1.0–4.0 μg of Pd (II) in 10 mL of solution. The calibration curve from 1.0 to 42.0 μg in 10 mL of solution is modeled successfully by artificial neural networks (ANNs). The maximum relative error between experimental values and the values predicted by ANNs is 1.5%. In comparison with some mathematical functions, ANNs show better ability for curve fitting, thus greatly extending the applicable range of the calibration curve of this new system. The method has been applied to determine Pd (II) in ore and catalyst samples with a relative error of less than 4% and with a recovery range between 94% and 103%. Received: 2 November 1999 / Revised: 5 January 2000 / Accepted: 10 January 2000     

Structural studies on some antimonate exchangers

The possibility of simultaneous extraction of palladium and technetium from nitrate solutions was investigated using tri-n-octylamine (TOA) solutions in carbon tetrachloride as a heavy, non-flammable diluent. Conditions of technetium extraction being essentially known, the main attention was focussed on the extraction of palladium which was studied in dependence on the concentration of nitric acid, salts (nitrates, chlorides, nitrites), urea and palladium. A strong decrease of Pd extraction with 10% TOA in CCl₄ has been found above a palladium concentration of 10⁻⁴M but in the presence of chlorides and nitrites a satisfactory high distribution can be preserved. Both Tc and Pd extracted with TOA/CCl₄ can be stripped into dilute ammoniacal solutions. An extraction procedure for the simultaneous isolation of Pd (80% yield) and Tc (99%) from fission product waste solutions (0.20 g Tc and 0.17 g Pd/dm³ 0.5–1.0M HNO₃) is proposed.     

Extraction of palladium from nitric acid medium and its spectrophotometric determination using arsenazo III

Summary Di-octyl sulphoxide in xylene was successfully employed for extracting palladium from 0.5 to 1.5 mol/l nitric acid medium. The extracted species was found to be Pd(NO₃)₂·2DOSO. The palladium was back extracted into a mixture of 2 mol/l sodium carbonate and 0.05 mol/l ammonia. The recovery was found to be quantitative. A spectrophotometric method using Arsenazo III was developed in nitric acid medium for the determination of palladium. The colour development was found to be maximum in the acid range of 2.5 to 5 mol/l. Beer's law was found to be obeyed in 1 to 100 g range of palladium. The molar extinction coefficient was found to be 2.26×10⁴ l/mol/cm. The RSD obtained at 16 g of palladium was 5%.     

Dinuclear and polynuclear palladium carboxylate complexes containing a Pd(μ-OCOR)<Subscript>2</Subscript>Pd group as a building block

The review considers palladium carboxylate complexes containing a Pd(μ-OOCR)₂Pd group, starting with dinuclear complexes and finishing with the currently largest octanuclear nitrosylcarboxylates, their structure, synthesis, and spectroscopic characteristics. We analyze the conditions for raising the nuclearity of carboxylate complexes and the conditions under which such attempts fail.     

Spectrophotometric determination of palladium with 4-(2-pyridylazo)resorcinol

Summary A simple photometric method for the determination of palladium has been worked out, employing pyridylazo-resorcinol (PAR) as a complexing ligand for the metal ion. The coloured species is extractable into chloroform in the presence of diethylamine, the absorbance of which is measured at 535 nm. The method is free from the interference of a large number of elements particularly the other platinum metals. It obeys Beer's law in the range of 0–3 g Pd/ml with Sandell's sensitivity of 0.0034 g Pd cm^–2. The ratio of metal to ligand in the complex is found to be 1:1. Analysis of various samples has been carried out with satisfactory and reproducible results (standard deviation ±0.002).     

The electronic spectra and structure of palladium(II) molecular complexes and clusters

The electronic absorption spectra of palladium(II) diacetate (PDA) complexes with phosphines and sulfides (D) with the composition Pd(OAc)₂ · 2D (1: 2) contain an intense charge transfer band at λ_max ∼ 300 nm (ɛ ∼ 15 000) and do not absorb in the region of 400 nm. Polynuclear compounds such as PDA trimer [Pd(OAc)₂]₃, trimer complexes with D, and four- and six-membered palladium metallocyclic compounds formed in the interaction of PDA with mercaptans absorb at longer wavelengths. The electronic absorption spectra of all the palladium polynuclear compounds (clusters) contain bands at λ_max ∼ 400 nm (ɛ ∼ 1000). The appearance of these bands in the spectra of palladium clusters is evidence of the formation of chemical bonds between neighboring Pd atoms, although Pd…Pd distances substantially exceed the sum of the covalent radii of palladium atoms.     

Direct determination of parts-per-billion levels of germanium in botanical samples and coal fly ash by graphite furnace atomic absorption spectrometry

 Parts-per-billion levels of germanium can be determined directly by graphite furnace atomic absorption spectrometry (GFAAS) using palladium plus strontium as a mixed modifier resulting in pyrolysis temperatures up to 1400 °C without loss of germanium. At this temperature the matrix effect including the most troublesome sulfate interference can be eliminated. Palladium plus strontium nitrate is advantageous compared to palladium alone or palladium plus magnesium nitrate; an amount of 15 μg of sulfate does not show any interference on the determination of 1 ng of germanium. The method was successfully applied to the determination of ng/g levels of germanium in botanical samples and coal fly ash after thermal decomposition of the samples in a mixture of acids using a pressure bomb. The results were consistent with the reference values given for botanical samples and coal fly ash with a recovery range of 96.4∼103.4% Received: 16 September 1996/Revised: 10 December 1996/Accepted: 14 January 1997     

Adsorption of 125I on palladium coated silver wire

The adsorption of ¹²⁵I on palladium coated silver wires was studied in this paper. The experimental conditions, e.g., reaction volume, carrier concentration, reaction time, reaction temperature, pH of the reaction mixture, were systematically optimized to obtain quantitative adsorption of ¹²⁵I on palladium coated silver wires. The experiments were performed using potassium iodide 8–9 μg as carrier in a reaction volume of 100 μL incubated in ~50 °C water bath for ~1 h, and the pH of the reaction system was controlled at 2–2.5. The distribution of activity on palladium coated silver wire was uniform, and the source cores can be easily sealed by laser welding into titanium capsules.     

Validation of a high-performance chromatographic method for determination of cefotaxime in biological samples

An analytical method for detecting and quantifying cefotaxime in plasma and several tissues is described. The method was developed and validated using plasma and tissues of rats. The samples were analyzed by reversed phase liquid chromatography (HPLC) with UV detection (254 nm). Calibration graphs showed a linear correlation (r > 0.999) over the concentration ranges of 0.5–200 μg/mL and 1.25–25 μg/g for plasma and tissues, respectively. The recovery of cefotaxime from plasma standards prepared at the concentrations of 25 μg/mL and 100 μg/mL was 98.5 ± 3.5% and 101.8 ± 2.2%, respectively. The recovery of cefotaxime from tissue standards of liver, fat and muscle, prepared at the concentration of 10 μg/g was: 89.8 ± 1.2% (liver), 103.9 ± 6.5% (fat) and 97.8 ± 2.1% (muscle). The detection (LOD) and quantitation (LOQ) limits for plasma samples were established at 0.11 μg/mL and 0.49 μg/mL, respectively. The values of these limits for tissues samples were approximately 2.5 times higher: 0.3 μg/g (LOD) and 1.25 μg/g (LOQ). For plasma samples, the deviation of the observed concentration from the nominal concentration was less than 5% and the coefficient of variation for within-day and between-day assays was less than 6% and 12%, respectively. The method was used in a pharmacokinetic study of cefotaxime in the rat and the mean values of the pharmacokinetic parameters are given. Received: 25 May 1998 / Revised: 27 July 1998 / Accepted: 1 August 1998     

Rhodium and palladium joint extraction by dihexyl sulfide and alkylanilinium nitrate mixtures from nitrate solutions

We studied nonequilibrium distribution of inert rhodium(III) in extraction by dihexyl sulfide (DHS)and alkylanilinium nitrate mixtures from joint nitrate solutions of triaquatrinitrorhodium (0.1–4 g/L Rh) and palladium (0–2 g/L Pd). We discovered the effect of increasing rhodium recovery in the presence of palladium. This effect has a kinetic nature and arises from the fact that bis(alkyl sulfide) palladium(II) species catalyze the reaction between dihexyl sulfide and a rhodium intermediate based on alkylanilinium nitrate micelles. Depending on initial rhodium and palladium concentrations, the extraction system provides effective distribution factors for rhodium in the range D _Rh* = 8−300 and rhodium recoveries of 43–97% with ∼100% palladium recovery; single 5-min phase contact at 35°C ensures the 10-fold concentration of both metals in the extract. Our results are useful for developing processes for recovering fission rhodium from spent nuclear fuel. Original Russian Text ? V.V. Tatarchuk, I.A. Druzhinina, T.M. Korda, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 8, pp. 1401–1407.     

Spectrophotometric determination of palladium with 2-mercaptomethyl-benzimidazole

Summary A spectrophotometric method has been developed for the determination of palladium with 2-mercaptomethyl-benzimidazole. This involves extraction of the palladium complex into iso-amyl alcohol in presence of 0.3 to 2N hydrochloric acid and 0.45 to 1.4M ammonium sulfate. The color is very stable and is highly selective for palladium. At 380 nm it obeys Berr's law in the concentration range of 1 to 9g of Pd per ml; the optimum range being 4 to 8g. The sensitivity and molar absorptivity of the reaction are 0.019g of palladium per cm² and 5600±70 respectively. The continuous variation and molar ratio methods indicate that palladium forms 12 complex with the ligand.

---

Zusammenfassung Eine spektrophotometrische Methode zur Bestimmung von Palladium mit 2-Merkaptomethylbenzimidazol wurde ausgearbeitet. Der Palladiumkomplex wird mit Isoamylalkohol in Gegenwart von 0,3- bis 2-n Salzsäure und von 0,45- bis 1,4-m Ammoniumsulfat extrahiert. Die Farbe ist sehr beständig und sehr selektiv für Palladium. Bei 380 nm entspricht die Färbung dem Beerschen Gesetz zwischen 1 und 9g Pd/ml; der optimale Konzentrationsbereich liegt zwischen 4 und 8g. Die Empfindlichkeit der Reaktion beträgt 0,019g Pd/cm²und die molare Absorption 5600±70. Die Untersuchung nachJob ergab für den Komplex das Molverhältnis Pd: Reagens= 12.

---

Résumé On a mis au point une méthode spectrophotométrique pour le dosage du palladium par le mercaptométhyl-2 benzimidazole. Elle met en jeu l'extraction du complexe du palladium par l'alcool isoamylique en présence d'acide chlorhydrique 0,3 à 2N et de sulfate d'ammonium 0,45 à 1,4M. La coloration est très stable et bien sélective pour le palladium. A 380 nm, elle suit la loi de Beer dans le domaine de concentration de 1 à 9g de Pd par ml; le meilleur domaine s'étend de 4 à 8g. La sensibilité et l'absorbance molaire de la réaction sont respectivement de 0,019g de palladium par cm² et 5600±70. Les méthodes des variations continues et du rapport molaire indiquent que le palladium forme un complexe 1,2 avec le coordinat.