Determination of metals by solid-liquid separation after liquid-liquid extraction Polarographic determination of indium after extraction with oxine into molten naphthalene

Indium has been extracted as its oxinate into molten naphthalene, the naphthalene allowed to solidify and then separated and dissolved in dimethylformamide, and the indium determined polarographically in dimethylforiaamide medium with pyridium perchlorate as supporting electrolyte.     

Liquid-liquid extraction and spectrophotometric determination of palladium(II) and ruthenium (III) with isonitrosoethylbenzoylacetate

Summary A method is described for the extractive spectrophotometric determination of palladium or ruthenium (III) using isonitrosoethylbenzoylacetate as the reagent. The yellow Pd-INEBA complex extracted into chloroform absorbs at 410 nm and conforms to Beer's law in the range of 10–110g of Pd per 10 ml of organic phase. The purple Ru-INEBA complex extracted into MIBK absorbs at 500 nm and conforms to Beer's law in the range of 25–125g of Ru per 10 ml of organic phase. The method affords the determination of both Pd and Ru in the presence of large number of cations and anions.

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Flüssig-flüssig-Extraktion und spektrophotometriscbe Bestimmung von Palladium(II) und Ruthenium(III) mit Isonitrosoäthylbenzoylacetat (IÄBA)

Zusammenfassung Eine Methode für die Extraktion und spektrophotometrische Bestimmung von Pd oder Ru mit IÄBA wurde beschrieben. Der gelbe Pd-Komplex absorbiert in chloroformischer Lösung bei 410 nm und entspricht dem Beerschen Gesetz für 10–110g Pd/10 ml organische Phase. Der rote Ru-Komplex absorbiert in MIBK bei 500 nm und entspricht dem Beerschen Gesetz für 25–125g Ru/10 ml. Das Verfahren eignet sich für die Bestimmung der beiden Metalle in Gegenwart zahlreicher Kationen und Anionen.

     

The separation of zinc(II) and cadmium(II) by liquid-liquid extraction

The extraction of Zn(II) and Cd(II) from thiocyanate solutions with bis-2-ethylhexyl sulphoxide (B₂EHSO) in benzene as an extractant has been studied by tracer techniques. For comparison, extraction has also been carried out with tributylphosphate (TBP). The extraction data have been analysed by both graphical and theoretical methods by taking into account complexation of the metal in the aqueous phase by inorganic ligands and plausible complexes extracted into the organic phase. The results demonstrate that Zn(II) is extracted as Zn(SCN)₂·2B2EHSO and Zn(SCN)₂·2TBP. In the case of Cd(II), the extracted species are Cd(SCN)₂·4B2EHSO/4TBP. The synergistic extraction of Zn(II) and Cd(II) with mixtures of 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP) and B2EHSO or TBP or trioctylphosphine oxide (TOPO) from acetate buffer solutions has also been investigated. Zn(II) is extracted as Zn(PMBP)₂·B2EHSO/TBP/TOPO. On the other hand, Cd(II) is found to be not extracted with these mixed-ligand systems under the experimental conditions. These results also demonstrate the mutual separation of Zn(II) and Cd(II) using the synergistic extraction with HPMBP in the presence of various neutral oxodonors.     

The spectrophotometric determination of manganese(VII) after extraction with the trimethylene-bis(triphenylphosphonium) cation with microcrystalline naphthalene

Summary Manganese(VII) (0–120 g) can be determined spectrophotometrically at 548 nm after its adsorptive extraction at pH 6 as its trimethylene-bis(triphenylphosphonium) ion pair with microcrystalline naphthalene after dissolution of the solid phase in chloroform. The effects of pH, reagent conditions and diverse ions are reported. The system has been applied to the determination of manganese in a range of steels. For the determination of 60 g of manganese the relative standard deviation was 0.61%.

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Spektralphotometrische Bestimmung von Mangan(VII) nach Extraktion mit dem Trimethylen-bis(triphenylphosphonium)- Kation mit Hilfe von mikrokristallinem Naphthalin

     

Simple and rapid flow-injection spectrophotometric determination of carbaryl after liquid-liquid extraction

A simple procedure was developed for the spectrophotometric determination of carbaryl and its hydrolysis product 1-naphthol in water. These compounds are extracted into xylene and back-extracted, as the 1-naphtholate, with 0.2 M NaOH. A 600-μl volume of the alkaline extract is injected into a flow analysis manifold which provides the reaction between naphtholate and 50 μg ml⁻¹ p-aminophenol solution in the presence of 0.004 M KIO₄ and spectrophotometric measurement is carried out at 596 nm. The method provides a limit of detection of 26.5 ng ml⁻¹ carbaryl and a sample frequency of 110 injections per hour. Recoveries in different types of matrices vary from 95 to 102%.     

Solvent extraction and spectrophotometric determination of palladium(II) with 7-iodo-8-hydroxyquinoline-5-sulphonic acid

An extractive spectrophotometric procedure has been developed for the determination of palladium (II) at microgram levels. The palladium(II) chelate of 7-iodo-8-hydroxyquinoline-5-sulphonic acid is extracted into n-butanol. Extraction is maximal (95%) from 0.2M perchloric acid. Beer's law is valid at 430 nm over a wide range of palladium concentration from 2.5 ppm. The molar absorptivity is 958 1.mole(-1).mm(-1). The system can tolerate a large excess of Co(II), Ni(II), Rh(III), Pt(IV), Cr(III), W(VI), chloride, phosphate, citrate and tartrate. Small quantities of Ru(III), IR(III) and EDTA do not interfere, but serious interference is caused by Fe(III), V(V), Mo(VI) and Os(VIII).     

Stopped-flow injection liquid-liquid extraction spectrophotometric determination of palladium in airborne particulate matter and automobile catalysts

A stopped-flow injection liquid-liquid extraction (SF-EX-FIA) spectrophotometric method is reported for the determination of palladium(II), using the 2,2'-dipyridyl-2-pyridylhydrazone (DPPH) as a color forming reagent. The colored complex Pd(II)-DPPH was extracted in CHCl(3) and the absorbance was monitored at 560 nm. An injection valve was used as a commutator in order to combine the stopped-flow technique with liquid-liquid extraction FI system. The calibration graph was linear up to 12 mg l(-1) (s(r)=0.27%; r=0.9999) with a detection limit of c(L)=0.007 mg l(-1). The sampling rate was 20 injections per hour. The proposed method has been successfully applied to the determination of palladium in airborne particulate matter (APM) and in automobile exhaust gas converter catalysts.     

Sensitive spectrophotometric determination of palladium with tin(II) chlorided and rhodamine-6g after flotation

Palladium is determined by reaction with tin(II) chloride and rhordamine-6G in hydrochloric acid medium, flotation of the ion-association complex, [(R6G⁺)₂Pd (SnCl^?₃)₄]·[(R6G⁺) (SnCl^?₃] with di-isopropyl ether, and dissolution in acetone for spectrophotometry. The molar absorptivity is 2.84 x 10⁵ l mol^?1 cm^?1 at 530 nm; Beer's law is obeyed in the range 0.05–0.35 μg Pd ml^?1. Other platinum metals and silver interfere. Traces of palladium in silver metal are determined after extraction of palladium with dimethylglyoxime in chloroform.     

Simultaneous extraction and spectrophotometric determination of cobalt(II) with thiothenoyltrifluoroacetone

Summary Thiothenoyltrifluoroacetone (1,1,1-trifluoro 4-(2-thienyl) 4-mer-captoput-en-3-2-one) is used for the simultaneous extraction and spectrophotometric determination ofg amounts of cobalt(II). 10 ml of 0.001M STTA in carbon tetrachloride quantitatively extracts, at pH 6.5, 20g of cobalt(II) as red orange colored complex which can be measured photometrically at 490 nm. The system conforms to Beer's law in the concentration range of 0.5–6.0g/ml of Cobalt(II). Studies on the effect of varying volume and concentration of the reagent, stability of the complex, and the period of equilibration were also reported. It is possible to extract and determine cobalt(II) quantitatively in the presence of large number of cations and anions. The method can be made selective by making use of appropriate masking agents.

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Zusammenfassung Thiothenoyltrifluoraceton [1,1,1-Trifluor-4 (2-thienyl)-4-mercaptobuten-3-2-on] (STTA) wurde für die gleichzeitige Extraktion und spektrophotometrische Bestimmung von Mikrogrammengen Kobalt(II) verwendet. 10 ml einer 0,001-m STTA-Lösung in Tetrachlorkohlenstoff extrahieren bei pH6,5 quantitativ 20g Co(II) als rotorangen Komplex, der bei 490 nm photometrisch gemessen werden kann. Zwischen 0,5 und 6,0g Co/ml ist das Beer'sche Gesetz erfüllt. Der Einfluß von Volumen und Konzentration des Reagens, die Stabilität der Komplexverbindung und die Extraktionsdauer wurden untersucht. Kobalt läßt sich so in Gegenwart vieler Kationen und Anionen quantitativ extrahieren und bestimmen. Bei Anwendung geeigneter Markierungsmittel ist die Methode selektiv.

     

Flow injection spectrophotometric determination of N-acetyl-L-cysteine as a complex with palladium(II)

We describe a new method using flow-injection analysis with spectro-photometric detection, suitable for the determination of N-acetyl-L-cysteine (NAC). The proposed method is appropriate for the determination of NAC in reaction with Pd(2+) ions in the concentration range from 1.0 × 10(-5) mol L(-1) to 6.0 × 10(-5) mol L(-1). The detection limit NAC was 5.84 × 10(-6) mol L(-1) and the recorded relative standard deviation of the method is in the range from 1.67 to 4.11%. NAC and Pd(2+) form complexes of Pd(2+):NAC molar ratios of 1:1 and 1:2, depending on the ratio of their analytical concentrations. The cumulative conditional stability constant for the Pd(NAC)(2)(2+) complex is β(12)' = 2.69 × 10(9) L(2) mol(-2). The proposed method was compared with the classic spectrophotometric determination of NAC, using the same reagent, PdCl(2), and had shown certain advantages: a) shorter analysis time; b) the use of smaller volumes of sample and reagents, which make the proposed method cheaper and faster for NAC determination in real samples without sample pretreatment.     

Spectrophotometric determination of cobalt after extraction of tetrathiocyanatocobaltate(II) with brilliant green into microcrystalline naphthalene

Cobalt (0–20 μg) is determined spectrophotometrically at 635 nm after its adsorptive extraction as tetrathiocyanatocobaltate(II) with Brilliant Green on microcrystalline naphthalene at pH 6.5 and dissolution of the solid phase in toluene. The effects of pH, diverse ions and making studies are reported. The system is applied to the determination of cobalt (0.2–10%) in high-speed tool steels without prior separation of iron.     

Liquid-liquid extraction and spectrophotometric determination of palladium with 2-mercaptobenz-amide

2-Mercaptobenzamide (MBA) was investigated as a reagent for the extraction of palladium. The palladium complex of MBA was extracted into tributyl phosphate (TBP). The pK_a of the ligand was 5.45 with the stability constant of the palladium complex β₂=10^7.1. The composition of the complex in TBP was Pd:MBA:TBP=1:2:2. Addition of sodium chloride accelerated the rate of extraction. Various interfering ions could be masked with EDTA; Ag(I), Au(III), Os(VIII), Se(IV), Te(IV) etc. interfered. The molar absorptivity was 1.59×10⁴ l mol^?1 cm^?1; 1–35 μg Pd could be determined at pH 6.0.     

1-（2′-苯并噻唑）-3-（4′-羧基苯）三氮烯固相萃取分光光度法测定钯

根据新试剂1-(2′-苯并噻唑)-3-(4′-羧基苯)三氮烯(BTCBT)与钯的显色反应及C8固相萃取小柱对显色络合物的固相萃取,建立了一种测定痕量钯的新方法,在pH为5.0~6.3的柠檬酸氢二钠-NaOH缓冲介质中,在乳化剂OP和SDBS存在下,钯与BTCBT发生反应形成1∶2的稳定络合物,该络合物可用C8固相萃取小柱富集,小柱上富集的络合物用乙醇洗脱后用分光光度法测定,在富集后的测定液中,络合物最大吸收波长为490 nm,摩尔吸光系数ε=1.16×105L.mol-1.cm-1,Pd2 量在0.1~1.2μg/mL内符合比尔定律,方法适用于测定催化剂中的钯。     

The spectrophotometric determination of cobalt by extraction of triphenylsulphonium tetrathiocyanatocobaltate(II)

Cobalt (0–130 μg) can be determined spectrophotometrically at 625 nm after its extraction as triphenylsulphonium tetrathiocyanatocobaltate(II) into 1:4 acetone/1,2-dichloroethane at pH 7. The effects of pH, diverse ions and masking studies are reported. The method is applied to the determination of cobalt (0.2–10.05) in high-speed tool steels without prior separation of iron, and in vitamin B12.     

The spectrophotometric determination of cobalt after extraction of tetramethylene-bis(triphenyl-phosphonium) tetrathiocyanatocobaltate(II) with microcrystalline benzophenone

Cobalt (0–130 μg) is determined spectrophotometrically at 625 nm after its adsorptive extraction as tetramethylene-bis(triphenylphosphonium) tetrathiocyanatocobalt(II) on microcrystalline benzophenone at pH 6.5 after dissolution of the solid phase in acetylacetone. The system is applied to the determination of cobalt (0.2–10%) in high-speed tool steels without prior separation of iron.     

Spectrophotometric determination of palladium after solid-liquid extraction with 1-(2-Pyridylazo)-2-naphthol at 90 degrees C

An effective spectrophotometric determination of palladium with 1-(2-pyridylazo)-2-naphthol (PAN) using molten naphthalene as a diluent has been studied. A green complex of palladium with PAN is formed at 90 degrees C. In the range of pH 1.5-7.5, the complex is quantitatively extracted into molten naphthalene. The organic phase is anhydrously dissolved in CHCl(3) to be determined spectrophotometrically at 678 nm against the reagent blank. Beer's law is obeyed over the concentration range of 0.5-10 ppm. The molar absorptivity and Sandell's sensitivity are 1.2 x 10(4) l mol(-1) cm(-1) and 0.0070 mg cm(-2), respectively. The optimum conditions for determination are obtained. The interferences of various ions are observed in detail. The method has been applied to the determination of palladium in synthetic samples.     

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%.

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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%.

     

Solvent extraction and spectrophotometric determination of palladium(II) with some nitrogen-containing heterocyclic hydrazones in the presence of chloride ions

Three terdentate hydrazones, all containing the 1-phthalazino grouping in the hydrazine moiety but differing in the heterocyclic substituent in the aldehyde moiety, have been used as analytical reagents for palladium(II), the optimal conditions for the extractive spectrophotometric determination of palladium(II) in the presence of chloride ions being deduced. These compounds are highly selective and sensitive reagents for palladium(II), since they are not extracted into chloroform from sulfuric acid solutions and do not react with other platinum group metals. The desirable spectral properties of the palladium(II) complex of benzothiazole-2-aldehyde-1-phthalazinohydrazone (BAPhH) have also been discussed with respect to preference of the C  N structural form in the heterocyclic ring on the aldehyde moiety of the ligand.