Liquid-liquid extraction of osmium thiocyanate with hexamethylphosphoramide and direct spectrophotometric determination in the organic phase

The use of hexamethylphosphoramide (HMPA) in the osmium-thiocyanate system makes the method more sensitive and selective. The blue colour formed by osmium(VIII) with thiocyanate in 1.5M hydrochloric acid is intensified in the presence of HMPA and the complex becomes readily extractable into chloroform. The colour system has its absorption maximum at 595 nm and obeys Beer's law over the range 0.5-16 mug of Os per ml. The optimum range is 2-10 mug/ml. The molar absorptivity is 2.09 x 10(4)l.mole(-1).cm(-1). The method is simple, sensitive and free from interference from many metal ions, including ruthenium and other platinum metals.     

Liquid-liquid extraction of cobalt(II) thiocyanate with hexamethyl phosphoramide: Direct spectrophotometric determination in the organic phase

Summary Use of HMPA in Co(II) thiocyanate colour system gives a simple, sensitive and selective method for the determination of Co(II). Maximum colour intensity is attained in the acidity range of 0.15–0.75M HCl and thiocyanate concentration of 0.5–1.0M. The colour is completely extractable into chloroform, when 2 to 4 ml HMPA is used. The colour system shows maximum absorption at 610 nm. The Beer's law range is 2 to 52g Co/ml with optimum concentration range of 6–48g Co/ml. The molar absorptivity and sensitivity are 1.24 x 10³ l·mole^–1·cm^–1 and 0.047g Co/cm² respectively. The method has been applied to the determination of cobalt in steel.

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Flüssig-flüssig-Extraktion von Kobalt(II)thiocyanat mit Hexamethylpbos-phoramid (HMPA) und spektrophotometrische Bestimmung in der organischen Phase

Zusammenfassung Auf der Grundlage der Farbreaktion von Kobalt(II)thiocyanat mit HMPA wurde eine einfache, empfindliche und selektive Methode zur Bestimmung von Co(II) entwickelt. Das Farbmaximum erhält man in 0,15–0,75M salzsaurer Lösung bei 0,5–1,0M Thiocyanat-Konzentration. Die Färbung ist mit Chloroform vollständig extrahierbar, wenn 2—4 ml HMPA verwendet werden. Die maximale Absorption liegt bei 610 nm. Der optimale Konzentrationsbereich liegt zwischen 6 und 48g Co/ml. Die molare Absorption beträgt 1,24 x l0³l·mole^–1·cm^–1, die Empfindlichkeit 0,047g Co/cm². Die Methode wurde zur Bestimmung von Kobalt in Stahl verwendet.

     

Liquid-liquid extraction of ferric thiocyanate with hexamethyl phosphoramide: Direct spectrophotometric determination in the organic phase

Summary Application of hexamethylphosphoramide (HMPA) in the iron(III)-thiocyanate system gives a simple, sensitive and highly selective method for the spectrophotometric determination of Fe(III) in the organic phase (CHCl₃). The color is stable for more than 24 hours in CHCl₃. The system obeys Beer's law for 7g Fe/ml and the optimum concentration range is found to be 0.5–5g/ml. The molar absorptivity of 1.33×10⁴ l·mole^–1·cm^–1, and Sandell's sensitivity is 0.0044/cm² at 460 nm The composition of Fe(III) to thiocyanate is found to be 13 in the presence of HMPA in CHCl₃. The method is free from interferences of many anions and cations. The method has been used to determine iron in bauxite ore.

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Flüssig-flüssig-Extraktion von Eisenrhodanid nach Zusatz von Hexatnethyl-pbosphoramid: Direkte spektrophotometrische Bestimmung in der organischen Phase

Zusammenfassung Der Zusatz von Hexamethylphosphoramid (HMPA) zu Eisen(III)-Thiocyanat führt zu einer einfachen, empfindlichen und sehr selektiven Methode der spektrophotometrischen Bestimmung von Fe(III) in organischer Phase (CHCl₃). Die Farbe bleibt in Chloroform mehr als 24 Stunden beständig. Das System entspricht dem Beerschen Gesetz unterhalb 7g Fe/ml. Das Konzentrationsoptimum liegt zwischen 0,5 und 5g/ml. Die molare Extinktion beträgt 1,33·10⁴ l·Mol^–1·cm^–1, die Empfindlichkeit nach Sandell 0,0044g/cm² bei 460 nm. Das Verhältnis Fe(III): Rhodanid in CHCl₃ ist 13 in Gegenwart von HMPA. Die Methode wird von vielen Anionen und Kationen nicht gestört. Sie wurde zur Bestimmung von Eisen in Bauxit verwendet.

     

Liquid-liquid extraction of molybdenum thiocyanate with hexamethyl phosphortriamide and direct spectrophotometric determination in the organic phase

A sensitive and selective method for estimation of trace molybdenum with fairly common reagents has been developed. The Mo-thiocyanate complex is extracted with hexamethyl phosphortriamide and chloroform from 0.75-1.5M hydrochloric acid. The molar absorptivity is 1.76 x 10(4) 1.mole(-1).cm(-1). The system obeys Beer's law at 460nm over the molybdenum concentration range 0.75-5ppm. The method is simple, rapid, and requires no additional reducing agent. It is generally free from interference by most of the metals commonly associated with molybdenum, including rhenium. Molybdenum in alloy steel has been successfully determined.     

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.

     

Liquid%liquid extraction of a rhenium%thiocyanate complex with hexamethylphosphoramide and direct spectrophotometric determination in the organic phase

A sensitive and selective method for the extraction of trace rhenium is based on extraction of a Re-thiocyanate complex with hexamethylphosphoramide and chloroform at an acidity of 2-3 M hydrochloric acid. Hydrazine sulphate is used as the reducing agent. The system obeys Beer's law at 430 nm, the optimum concentration range is 1.7-8 ppm. The molar absorptivity is calculated to be 2.23 x 10(4) 1.mole(-1) .cm(-1). The colour is stable for at least 48 hr. The method is simple and rapid and is generally free from interference by most of the metals commonly associated with rhenium.     

Liquid-liquid extraction of zirconium with tri-n-butyl-acetohydroxamic acid and spectrophotometric determination in the organic phase with xylenol orange

Zirconium (6–121 μg) is determined with xylenol orange after liquid-liquid extraction by tri-n-butylacetohydroxamic acid (TBAH) from 6 M hydrochloric acid. Under optimal conditions (primarily, 1 1:1.5 ratio of TBAH to xylenol orange, addition of acetic acid, and measurement at 545 nm), the calibration is linear with a molar absorptivity of 34 650 l mol^?1 cm^?1. Ions which are not extracted by TBAH or donot form coloured complexes do not interfere; these include uranium and rare-earth elements. Hafnium interferes; interference from thorium is avoided by a preliminary extraction of zirconium with tri-n-octylamine.     

Rapid extraction of iron(III) with 2-thenoyl trifluoroacetone : Direct colorimetric determination in the organic phase

2-Thenoytrifluoroacetone is investigated for the rapid extraction and spectrophotometric determination of iron(III) at the milligram level. The red extract absorbs strongly below 400 mμ. The color is stable for many hours, Beer's law is obeyed at 460 mμ for 1–10 μg of iron/ml. Interferences are studied. The method is reproducible to ±1%.     

Rapid spectrophotometric determination of ruthenium(III) with prochlorperazine maleate

A rapid, simple spectrophotometric method for the determination of μg amounts of ruthenium, based on the formation of a pink complex between the metal and prochlorperazine maleate (PCPM) in sulphuric or hydrochloric acid solution, is described. The complex has an absorption maximum at 530 nm and its molar absorptivity is 6.733·10³ l mol^?1 cm^?1. The sensitivity is 0.0151 μg Ru cm^?2 for log I_o/I = 0.001. Beer's law is valid over the range 0.2–10 μg Ru ml^?1 ; the optimal range for spectrophotometric determination is 0.8–8.0 μg Ru ml^?1. Job's method of continuous variation, the mole ratio method and the slope ratio method indicate a 1:1 composition for the complex. The effects of acidity, time, temperature, order of addition of reagents, reagent concentration, and the interferences from various ions are reported.     

Direct spectrophotometric determination of rare earths in organic extracts with chlorophosphonazo III

The highly sensitive spectrophotometric determination of rare earths after extraction into di(2-ethylhexyl)phosphoric acid and trioctylamine is described. A sample of extract is diluted with n-butanol, the solution of chlorophosphonazo III in n-butanol is added, and the solution is made up to defined volume. Absorbance is measured at 660–665 nm against a reagent blank. The method is suitable for the study of the extraction of individual rare earths by different organic extrahents.     

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.     

Liquid-liquid extraction and spectrophotometric determination of uranium with n-phenyl-3-styrylacrylohydroxamic acid (PSAHA)

A rapid, selective and sensitive liquid-liquid extraction and spectrophotometric method for the separation and microgram determination of uranium using PSAHA is described. Uranium is extracted with PSAHA into chloroform at pH 6.0–6.8. The U-PSAHA chelate is orange red in color having maximum absorbance at 410 nm and molar absorptivity 1.2·10⁴l·mol^–1·cm^–1. The system obeys Beer's Law in the range of 1.2 to 22.00 ppm of uranium. The uranium is determined in sea water and rock samples.     

Liquid-liquid extraction of cobalt thiocyanate with trhsooctylamine

Cobalt forms a coloured complex with triisooctylamine and thiocyanate in carbon tetrachloride. The green organic phase has maximum absorbancc at 627.5 mμ and Beer's law is obeyed in the range 0–10 mg Co. The molar extinction coefficient is 1895. The distribution coefficient at room temperature is 5.6. A composition of the coloured species is proposed.     

Propericiazine as a reagent for the spectrophotometric determination of ruthenium(III)

Propericiazine forms an orange-red species with ruthenium(III) immediately in 6–8 M phosphoric or hydrochloric acid or 4.5–5.5 M sulphuric acid. The absorption maximum is at 511 nm and the molar absorptivity is 1.1 × 10⁴ 1 mol^?1 cm^?1. Beer's Law is obeyed over the range 0.2–9.4 mg 1^?1 (optimum range 0.5–9.0 mg 1^?1). Interferences are described. The method is used to determine ruthenium in synthetic zinc–magnesium alloy and uranium alloy (fuel) solutions.     

Reversed phase extraction chromatographic separation of ruthenium(III)

A new an innovative separation method has been developed using N-n-octylaniline (liquid anion exchanger) coated on silica gel. Ruthenium(III) has been extracted quantitatively from 0.05 M hydrochloric acid, striped with aqueous solution of various acids and then determined by spectrophotometric method. Mutual separation scheme for ruthenium(III), iridium(III) and osmium(VIII) has been developed. Ruthenium(III) has been separated from commonly associated elements. Different parameter are studied viz effect of acid concentration, reagent concentration, striping agent, flow rate, foreign ion and synthetic mixture corresponding to alloys. Validity of method has been verified by separation of ruthenium(III) from fissium alloy.     

Solid phase extraction and spectrophotometric determination of trace amounts of thiocyanate in real samples

A simple, selective and rapid method for solid phase extraction and spectrophotometric determination of thiocyanate using a manganese (III) tetrakis (p-sulfonatophenyl) porphyrin, [Mn (TPPS) OAC] bound to Amberlite IR-400 has been developed. The influence of pH, amount of solid phase, sample matrix, type and amount of eluting agent and flow rates i.e. variables affecting the efficiency of the extraction system were evaluated and conditions of the sample, eluting solution and active phase were optimized. The maximal capacity was found to be as 1.16 microg mL(-1) for 1200 mL. Thiocyanate ions can be eluted quantitatively with 8 mL 0.3 M ferric chloride. The enrichment factor was 150. The linear range of the determination is between 0.4-2.0 microg mL(-1) for preconcentration method with a limit of detection of 2.8 ng mL(-1). The method has been successfully applied for determination of trace amounts of thiocyanate in tap water, saliva sample and a synthetic mixture.     

Synergetic extraction and spectrophotometric determination of gold(III)

Summary A method is described for the synergetic extraction and subsequent spectrophotometric determination of gold(III). The gold--furil dioxime-pyridine complex extracted into chloroform has a characteristic yellow colour with an absorption maximum at 330 nm. Beer's law is obeyed in the concentration range [Au(III)]45g/ 10 ml organic phase. A scheme to separate gold from interfering elements by extraction with 4-methyl-2-pentanol in benzene has been proposed.

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Zusammenfassung Ein Verfahren zur synergetischen Extraktion und nachfolgenden spektrophotometrischen Bestimmung von Gold(III) wurde beschrieben. Die Komplexverbindung des Goldes mit-Furildioxim und Pyridin ist in chloroformischer Lösung gelb gefärbt. Ihr Absorptionsmaximum liegt bei 330 nm. Bis 45g Au(III)/10 ml organischer Phase wird das Beersche Gesetz befolgt. Die Trennung des Goldes von störenden Elementen durch Extraktion mit 4-Methyl-2-pentanol in Benzol wurde vorgeschlagen.

     

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.