Extraction spectrophotometric investigation of mixed ligand complex of molybdenum(V) with thiocyanate and 4-acetyl-2-(acetylamino)-5-dimethyl-Δ2-1,3,4-thiadiazole

A sensitive spectrophotometric method is developed for the determination of small amounts of molybdenum based on the extraction of molybdenum-thiocyanate-4-acetyl-2-(acetylamino)-5-dimethyl- ²-1,3,4-thiadiazole complex into chloroform from hydrochloric acid medium which is orange red in colour. The complex has an absorption maximum at 470 nm with a molar absorptivity of 2.01×10⁴l·mole^–1·cm^–1. Beer's law is valid over the concentration range 0.06–2.5 ppm of molybdenum with an optimum concentration range of 0.15–2.2 ppm. The ternary complex is stable for over one week at room temperature. Equilibrium shift method indicates 142 composition for molybdenum-thio-cyanate-4-acetyl-2-(acetylamino)-5-dimethyl- ²-1,3,4-thiadiazole complex. The effects of acidity, reagent concentrations, time, temperature and diverse ions upon the absorbance of the complex are critically assessed. This method has been used successfully for the determination of molybdenum in molybdenum steels.     

Spectrophotometric determination of iron with chelidamic acid

Summary Chelidamic acid forms with iron a complex at p_H 5.8 to 8.5 having the maximum absorption at 460 nm. The metal to reagent ratio is 13 and the instability constant is about 8.21 · 10^–15. The complex obeys Beer's law from 0.4 to 16 ppm of iron and the optimum concentration range is 1 to 8 ppm, with a relative analysis error of 2.3% per 1% absolute photometric error.

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Zusammenfassung Chelidamsäure bildet mit Eisen beiph 5,8–8,5 einen Komplex, der bei 460 nm ein Absorptionsmaximum aufweist. Das Verhältnis Metall: Reagens beträgt 13, die Instabilitätskonstante etwa 8,21 · 10^–15 Das Beersche Gesetz wird im Bereich von 0,4–16 ppm befolgt, der optimale Konzentrationsbereich liegt bei 1–8 ppm. Der relative Fehler beträgt 2,3% je 1% absoluten photometrischen Fehler.

     

O-carboxyphenyl azo chromotropic acid (sodium salt) as an analytical reagent

Summary 0-carboxyphenyl azo chromotropic acid (sodium salt), named as chromotrope 2 C, is used as a new colorimetric reagent for the determination of micro amounts of thorium and aluminium. The blue-violet and red-violet complexes show maximum absorption at 590 nm and the colour systems obey Beer's law from 0.1 to 8 ppm for thorium and 0.1 to 1ppm for aluminium. However, their optimum concentration ranges are from 1.6 to 8 ppm for thorium and 0.2 to 0.8 ppm for aluminium, where the percent relative errors per 1% absolute photometric error are, respectively, 3.06 and 2.94. The composition of the complexes, as elucidated by the continuous variation method, suggests a metal to reagent ratio of 23 for thorium and a ratio of 11 for aluminium. The instability constants for the complexes are of the order of 4.044×10^–10 and 1.006 × 10^–6 at 30°C.Part I, see Z. analyt. Chem. 174, 197 (1960)     

Spectrophotometric determination of beryllium and zirconium using chromotrope-2C

Summary Disodium salt of o-carboxyphenylazo chromotropic acid (chromotrope 2C) has been used for the colorimetric determination of microamounts of beryllium and zirconium. The red-violet complexes show maximum absorption at 580 nm and the colour systems obey Beer's law from 0.025 to 0.375 ppm of beryllium and 2 to 12 ppm of zirconium. The optimum concentration ranges are from 0.125 to 0.375 ppm for beryllium and from 4 to 12 ppm for zirconium, where the percent relative errors per 1% absolute photometric error are, respectively, 3.014 and 3.22. The sensitivity of the reactions per cm² are 0.00067 g Be and 0.027 g Zr. The complexes, with the metal to reagent ratio of 11, have instability constants as 2.836 · 10^–6 for beryllium and 6.026 · 10^–6 for zirconium.     

Spectrophotometric determination of platinum

Summary Anthranilic acid when heated on the steam bath with chloroplatinic acid at p_H 5.0 gives a reddish violet complex having absorption maximum at 500 nm. The violet coloured system obeys Beer's law from 4 to 64 ppm of platinum (IV) with an optimum concentration range of 16 to 48 ppm where the per cent relative error per 1% absolute photometric error is 2.87.Composition studies by three techniques suggest the formation by platinum(IV) of a 11 complex with the reagent, and the dissociation constant of the complex is 2.6 · 10^–4 only when measured at 28° C.     

Flotation and spectrophotometric determination of silver with 4-(p-nitrophenylazo)-2-amino-3-pyridinol

A sensitive flotation-spectrophotometric method, based on the complex formed between Ag(I) and 4-(p-nitrophenylazo)-2-amino-3-pyridinol is described. The complex precipitates when the aqueous solution is shaken with benzene, and the solid formed is then dissolved in dimethylformamide. The molar absorptivity of the resulting solution is 10.7×10⁴l·mole^–1·cm^–1 at 605 nm. Beer's law is obeyed between 0.08 and 1 ppm of silver. The molar ratio of Agreagent in the separated complex is 12. The effect of foreign ions has been determined and the proposed method can be applied to determination of silver in an exhausted photographic developing solution.     

Spectrophotometric determination of osmium

Summary m-Amino benzoic acid in large excess reacts with tetra-, hexa- and octavalent osmium at theph range 4.5–6 to give a purple complex having absorption maximum at 500 nm. Beer's law is obeyed for 0.5 to 8 ppm of osmium(VI) and osmium(VIII) with optimum concentration range of 2 to 8 ppm of osmium(VI) and 3 to 8 ppm for osmium(VIII). The per cent relative error per 1% absolute photometric error is 2.8 for both osmium(VI) and osmium(VIII). Ions such as Pd²⁺, Rh³⁺, Ir⁴⁺, W⁶⁺, U⁶⁺, Co²⁺, Hg²⁺, Mg²⁺, Ca²⁺, Ba²⁺, Sr²⁺, Th⁴⁺ and Zr⁴⁺ do not interfere in the determination.Molar ratio method indicates that the reagent first reduces osmium (VIII) and osmium(VI) to osmium(IV), which then probably forms a 11 complex with the excess unoxidised reagent.Part III.: Anal. chim. Acta 22, 306 (1960); cf. Z. analyt. Chem. 177, 291 (1960).     

Spectrophotometric determination of rhenium using 2-pyridyl thiourea

The reagent 2-pyridyl thiourea produces a reddish brown complex with rhenium in hydrochloric acid medium in the presence of tin(II) chloride. The complex shows absorption maxima at 405 nm, obeys Beer's law for a range of 1–16 ppm of rhenium. The sensitivity and molar absorptivity is found to be 0.0115g cm^–2 and 1.603×10⁴ 1 mol^–1 cm^–1 respectively showing an improvement over other sulphur-nitrogen bearing ligands. Composition found by Job's and mole ratio method, indicates that the complex contains metal and reagent in the ratio 12. Stability constant and stepwise formation constants of the complex have been evaluated by Harvey-Manning's method (logK _overall=8.825), Leden's method (logK _overall=8.3096), Rossotti-Rossotti's method (logK _overall=8.653) and Yatsimirskii's method (logK _overall=8.740). The relative error per 1% absolute photometric error is found to be 2.7%.     

5-(4-Carboxylphenylazo)-8-aminoquinoline as an analytical reagent for the spectrophotometric determination of gold

The synthesis and analytical application of 5-(4-carboxylphenylazo)-8-aminoquinoline (CPAQ) are described. A simple, rapid, selective, and sensitive spectrophotometric method for the determination of microgram amounts of gold is developed, based on the colour reaction between the metal ion and CPAQ in the presence of cetyltrimethyl ammonium bromide. Gold (III) reacts with the reagent in the ratio 1 3 (metal to ligand) in alkaline solution to form a blue-green complex with an absorption maximum at 608 nm. Beer's law is obeyed over the concentration range 0–1.8 g · ml^–1 (ppm) of gold. The molar absorptivity and Sandell's sensitivity of the method are 9.11 × 10⁴ l · mole^–1 · cm^–1 and 0.00216 g · cm^–2, respectively. The interference of various ions has been studied and conditions were developed for the determination of gold in an ore and anode slimes.     

Colorimetric estimation of thorium with carmine red

The use of carmine red as a colorimetric reagent for thorium in presence of a 20 fold excess of cerite earths or a 5 fold excess of uranyl salts is described, p_H of 2.5 and the wavelength 560 m were found most suitable. The ratio of thorium to reagent in the complex is shown to be 14 from spectrophotometric data. It is also shown that the complex dissociates little under these conditions.     

2-[2′-(6′-Methyl-benzothiazolyl)azo]-5-dimethylaminobenzoic acid as a new reagent for rapid spectrophotometric determination of copper

2-[2-(6-methyl-benzothiazolyl)azo]-5-dimethylaminobenzoic acid (MBTAMB) has been synthesized and employed as a new reagent for the spectrophotometric determination of copper(II). A blue complex is formed from MBTAMB and Cu(II) in the range of pH 2.0–5.0 in aqueous ethanol. The composition of the complex is Cu(II) MBTAMB=1 1. The maximum absorption of the complex is at 660 nm, its apparent molar absorptivity is 7.0 × 10⁴ 1· mole^–1 · cm^–1. Beer's law is obeyed for copper in the range of 0–0.72 g/ml. The method has been used for the determination of micro amounts of copper in aluminium alloy. The proposed method is simple, rapid and accurate.     

A sensitive spectrophotometric method for the determination of trace amounts of uranium (VI) using o-hydroxypropiophenone isonicotinoyl hydrazone

The reaction between uranium (VI) and o-hydroxypropiophenone isonicotinoyl hydrazone (OHPINH) has been investigated in HCl-sodium acetate buffers and a highly sensitive and simple procedure for the determination of uranium (VI) is suggested. The yellow colored complex showed maximum absorption at 380 nm in buffer solutions of pH 3. Beer's law is obeyed in the range of 0.47–17 g ml^–1. The molar absorptivity and Sandell sensitivity are found to be 1.15×10⁴ dm³ mol^–1 cm^–1 and 0.02 g cm^–2, respectively. The composition of the complex is found to be 11 between metal and reagent.     

Tungsten(VI) complexes formed in an excess of gluconic acid: A polarimetric and spectrophotometric study

Summary The tungsten(VI)-gluconic acid system in an excess of this organic reagent has been spectroscopically and polarimetrically studied and four species, two mononuclear with stoichiometry 12 (metalligand) and two dinuclear with composition 22, have been identified. The non-formation of a binuclear species with stoichiometry 21 (metalligand) demonstrates some preference towards coordination of carboxylate group.The pH of the medium is the main variable controlling the formation and interconversion equilibria, which are similar to those previously described for other -hydroxyacids ligands. Thus, the three species being stable at a lower pH require for their formation from [WO₄]^2– and gluconate ions, 2,2 and 2.5H⁺/W, respectively.However, for pH values higher than 9.0, where the carboxylic group may be assumed not to coordinate, a fourth weaker monomeric complex is formed, similar to those formed by mannitol or sorbitol at the same pH.     

Extraction-spectrophotometric determination of iron(III) by means of quinaldic acid-N-oxide

Summary A simple and sensitive method for the determination of iron(III) is described. It is based on the extraction of the yellow-coloured complex of iron with quinaldic acid-N-oxide in chloroform. The absorption maximum is at 380 nm with molar absorptivity ₃₈₀=1.03 · 10⁴. Beer's Law is obeyed over the range 0.6–6 ppm iron with relative standard deviation of +-0.3% (Sandell sensitivity 0.005 g/ml/cm²). The absorbance of the reagent blank is however high with consequent occasional disturbances, which are avoided when measured at 395 nm; molar absorptivity ₃₉₅=7.4 · 10³; effective concentration range 3–8 ppm iron with relative standard deviation +-0.5% (Sandell sensitivity 0.008g/ml/cm²). A fairly large number of common ions do not interfere. Job's method of continuous variations and Asmus method indicate a iron-reagent ratio of 13. Heterogeneous formation constant is K _D =2 · 10⁸.

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Extraktionsphotometrische Bestimmung von Eisen(III) mit Chinaldinsäure-N-oxid

Zusammenfassung Die einfache und empfindliche Bestimmung beruht auf der Extraktion des gelben Komplexes von Eisen(III) mit Chinaldinsäure-N-oxid in Chloroform. Das Absorptionsmaximum liegt bei 380 nm mit dem molaren Extinktionskoeffizient ₃₈₀=1.03 · 10⁴. Das Beersche Gesetz gilt im Bereich 0,6–6 ppm Eisen. Die relative Standardabweichung beträgt+-0,3% (Sandell-Empfindlichkeit 0,005g/ml/cm²). Die Absorption der Blindprobe ist jedoch hoch und verursacht manchmal Störungen, die beim Messen bei 395 nm vermieden werden; molarer Extinktionskoeffizient ₃₉₅= 7,4 · 10³; im Konzentrationsbereich 3–8 ppm Eisen beträgt die relative Standardabweichung+-0,5% (Sandell-Empfindlichkeit 0,008g/ml/cm²). Eine ziemlich große Zahl von Fremdionen bewirkt keine Störung. Methoden nach Job und Asmus liefern ein Verhältnis Eisen/Reagens wie 13. Die heterogene Bildungskonstante beträgt K _D =2 · 10⁸.

     

Extraction-spectrophotometric determination of trace iron (II) in sea water with 2-[2-(3,5-dibromopyridyl)azo]-5-diethylaminobenzoic acid

An extraction-spectrophotometric method is described for the determination of traces of iron(II) with 2-[2-(3,5-dibromopyridyl)azo]-5-diethyl-aminobenzoic acid. The reagent forms a stable and blue 12 iron/reagent complex that can be extracted into chloroform. The apparent molar absorptivity of the iron(II) complex is 1.09 × 10⁵ 1 mol^–1 cm^–1 at 624 nm in chloroform. The reagent is relatively selective; interferences from cobalt, copper, nickel and vanadium can be removed by using dimethylglyoxime and EDTA. The method is applied to the determination of iron (II) in sea water and aluminium alloys with good precision and accuracy.     

A rapid chromatographic method for the estimation of thorium in rocks, soils and low grade ores

Summary A simple and rapid field Chromatographic method for the determination of thorium in ppm quantities in rocks, soils and low grade ores using paper strip chromatography is described. An aliquot of an hydrochloric acid solution of the sample is taken on a special paper (Chromatographic paper of C.R.L./l grade) and the paper is then placed into a beaker containing the solvent mixture consisting of methyl alcohol, acetone, 2-thenoyl trifluoroacetone and hydrochloric acid in the ratio 12 ml6 ml0.04 g2 ml (13) respectively.A saturated alcoholic solution of alizarin atph 2.8-2.4 is used as developing reagent.This method is applicable to samples containing from 0.2 ppm to 1000 ppm of thorium.

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Zusammenfassung Eine einfache und schnell durchführbare Feldmethode zur papierchromatographischen Bestimmung von ppm-Mengen Thorium in Gesteinen, Böden und Erzen niederen Gehaltes wird beschrieben. Hierbei wird ein Anteil der salzsauren Probelösung auf ein Spezialpapier (C.R.L./ 1 grade) aufgebracht und dieses in einem Becherglas mit einem Gemisch aus Methanol, Aceton, 2-Thenoxyltrifluoraceton und Salzsäure (12 ml 6 ml0,04 g2 ml [13]) chromatographiert. Zur Entwicklung dient eine gesättigte alkoholische Alizarinlösung (ph 2,8-2,4). 0,2–1000 ppm Thorium können nach diesen Verfahren bestimmt werden.

     

Tropolone as an analytical reagent for microdetermination of rhodium(III)

Summary Tropolone forms a water-soluble yellow complex with rhodium-(III), which is extractable into chloroform containing pyridine. Although max of the complex lies at 390 nm, the more suitable wave-length for the determination is 420 nm at which there is practically no absorption by the reagent. The composition of the complex, as determined by Job's and logarithmic methods, comes out to be 1 2. The pH range for maximum colour development is 5.5–6.3. Beer's law is followed up to 9.0 ppm and sensitivity of the colour reaction at 420 nm is 0.009g Rh/cm². The effect of various foreign ions has been investigated. With simple modifications, the method becomes highly selective.

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Zusammenfassung Tropolon (Cykloheptatrienolon) bildet mit Rhodium(III) eine gelbe, wasserlösliche Komplexverbindung, die sich mit pyridinhältigem Chloroform extrahieren läßt. Das Absorptionsmaximum liegt zwar bei 390 nm, aber für die Messung eignet sich die Wellenlänge 420 nm besser, die von dem Reagens selbst praktisch nicht absorbiert wird. Die Zusammensetzung des Komplexes wurde nachJob und nach logarithmischen Methoden bestimmt und entspricht dem Verhältnis 1 2. Maximale Farbintensität wird bei pH 5,5–6,3 erreicht. Das Beer'sche Gesetz ist bis 9,0 ppm gültig, die Empfindlichkeit bei 420 nm entspricht 0,009g Rh/cm². Der Einfluß verschiedener Fremdionen wurde untersucht. Mit einfachen Vorkehrungen wird die Methode hoch selektiv.

     

Spectrophotometric determination of platinum using the diethazine hydrochloride complex

Summary Diethazine hydrochloride forms an yellowish-green complex with platinum(IV) in sodium acetate-hydrochloric acid buffer containing copper catalyst. The complex has an absorption maximum at 404nm and its molar absorptivity is 1.083×10⁴l mole^–1cm^–1. The sensitivity is 18 ng/cm² for logI ₀/I=0.001. Beer's law is valid over the concentration range 0.5–12.0 ppm. The composition of the complex as determined by the continuous variations, mole ratio and slope ratio methods is 11 and the apparent stability constant of the complex at pH 2.3 and 27° has the log K value of 5.83. The effects due to pH, reagent concentration, copper concentration, time and diverse ions are reported.

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Zusammenfassung 10-(2-Diäthylaminoäthyl)-phenothiazinhydrochlorid (DH) bildet mit Platin in Natriumacetat-Salzsäure-Puffer, der Kupfer als Katalysator enthält, eine gelbgrüne Komplexverbindung. Diese hat ein Absorptionsmaximum bei 404 nm, ihre molare Extinktion beträgt 1,083×10⁴l·mol^–1·cm^–1. Die Empfindlichkeit entspricht 18 ng/cm² für logI ₀/I=0,001. Das Beersche Gesetz gilt zwischen 0,5 und 12,0 ppm. Der Komplex ist im Verhältnis 11 zusammengesetzt. Die scheinbare Stabilitätskonstante bei pH 2,3 und 27° C entspricht logK=5,83. Über den Einfluß von pH, Reagenskonzentration, Kupferkonzentration, Zeit und verschiedene Fremdionen wurde berichtet.

     

N-Methylethylxanthocarbamate as an Analytical Reagent: Differential Pulse Polarographic Determination of Cadmium in Standard Alloys, Biological and Environmental Samples after Adsorption of its Complex on Microcrystalline Naphthalene

N-methylethylxanthocarbamate has been used as an analytical reagent for the determination of trace amounts of cadmium in standard alloys, biological, and environmental samples. The reagent has been found to form a water insoluble complex with cadmium. It is quantitatively adsorbed over microcrystalline naphthalene in the pH range 2.5 to 12.0. The metal complex is desorbed with HCl and cadmium determined with a differential pulse polarograph. The detection limit is 0.05 ppm (signal-to-noise ratio = 2) and the linearity is maintained in the concentration range 0.2–25 g/ml, with correlation coefficient of 0.9995 and a relative standard deviation of ±0.81%. Characterization of the electroactive process includes an examination of the degree of reversibility. Various parameters, such as the effect of pH, reagent concentration, amount of naphthalene, volume of aqueous phase, and the interference of a large number of metal ions on the determination of cadmium, have been studied in detail to optimize the conditions for its determination in various complex materials.     

BISPHENYLENECOSAN as highly selective Cs+ extraction agent

A new reagent for the highly selective extraction of cesium (e-1,7–2,2)4,8–8,4-(bis--o-phenylene)bisdicarbollidocobalt(1–)ate, [(C₂B₉H₉)₂(C₆H₄)₂Co]^–, abbreviated as BISPHECOSAN is described in this paper. The choice of organic solvent and solubilizer, dependence of distribution ratio of Cs⁺ on acidity and other parameters are studied. The extraction mechanism based on selective binding of Cs⁺ cation between two phenylene rings is presented and factors influencing the chemical stability of the reagent are determined.