Niobium(III) as an analytical reagent. : Part I. The titrimetric determination of iron,copper, thallium,molybdenum, uranium and vanadium

Niobium(III) solutions can be used in direct titrations of copper(II), iron(III), thallium(III), moIybdenum(VI), vanadium(V) and uranium(VI) in milligram amounts. Phenosafranine is generally satisfactory as the indicator, but potentiometric end-points can also be used. Copper and iron can be determined successively when a mixed indicator containing phenosafranine and méthylene blue is used. Thallium(I) and thallium (III) can be determined in mixtures. The niobium (III) solutions are stable for several days under a carbon dioxide atmosphere.     

Hydrazine sulphate as reagent for titrimetric determination of vanadium(V) and chromium(VI)

Conditions have been developed for the direct titration of vanadium(V) and chromium(VI) with hydrazine sulphate, barium diphenylaminesulphonate being used as indicator and osmium tetroxide as catalyst.     

Diformylhydrazine as analytical reagent for spectrophotometric determination of iron(II) and iron(III)

The bidentate ligand diformylhydrazine (OHC-HN-NH-CHO), DFH, combines with iron(II) and iron(III) in alkaline media in the pH range 7.3-9.3 to form an intensely colored red-purple iron(III) complex with an absorption maximum at 470 nm. Beer's law is obeyed for iron concentrations from 0.25 to 13 microg mL(-1). The molar absorptivity was in the range 0.3258x10(4)-0.3351x10(4) L mol(-1) cm(-1) and Sandell's sensitivity was found to be 0.0168 microg cm(-2). The method has been applied to the determination of iron in industrial waste, ground water, and pharmaceutical samples.     

Spectrophotometric determination of vanadium(v) and its application to vanadium steels containing chromium, molybdenum, tungsten and manganese

A newly synthesized reagent, N-o-toluoyl-N-o-tolylhydroxylamine is used in a sensitive and selective spectrophotometric method for determination of vanadium(V). The method has been successfully applied to vanadium determination in Mn-Mo-Cr-V steels. The system in 2-6M hydrochloric acid medium obeys Beer's law at 510 nm in the range of vanadium concentration from 0.5 to 10.0 mug ml .     

Spectrophotometric determination of vanadium(V) and its application to vanadium steel containing chromium,molybdenum, manganese,and nickel

Promethazine hydrochloride forms a red colored species with vanadium(V) in 6.0–7.5 M phosphoric acid. A 16-fold molar excess of the reagent is necessary for full development of color intensity. Beer's law is valid over the concentration range of 0.1–7.0 ppm. The optimum concentration range as evaluated by Ringbom's method is 0.5–7.0 ppm. The sensitivity of the reaction is 0.005 μg cm^?2 and the molar absorptivity is 9.60 × 10³ liter mol^?1 cm^?1 at 517 nm. The effects of acidity, time, temperature, order of addition of reagents, reagent concentration, and the interferences from various ions were reported. Vanadium in vanadium steel containing chromium, molybdenum, manganese, and nickel was determined.     

Acetylacetone as chelating reagent, extracting solvent, and electrolysis medium: Polarographic determination of uranium(VI) and iron(III)

The chelating reagent acetylacetone has been examined as a polarographic medium; a method for its purification has been developed and it is found that the specific conductance is 4.2 x 10(-8) mho/cm, the accessible potential ranges are from -0.16 to -2.26 V vs. Ag/0.1M AgClO(4) for the pure solvent and from -0.35 to -2.20 V in the solvent after extraction. In pure solvent ferric acetylacetonate exhibits one wave and the uranyl complex gives two waves. After extraction from aqueous solution at pH 6.8-7.0, both metal acetylacetonates are reduced more reversibly and at more positive potential than in the pure solvent. Calibration curves are linear in the range 10(-5) -10(-3)M metal ion in the extract. The direct polarographic determination of uranium and iron in acetylacetone after extraction of the chelate from aqueous solution has been developed.     

Resorcinol as an analytical reagent for the spectrophotometric determination of uranium

A spectrophotometric study of the reaction of uranyl acetate and resorcinol shows that an orange-red coloured resorcinolate of composition 1:2 is formed. This colour reaction can be conveniently used for the spectrophotometric estimation of uranium at PH 4.72.     

Isophthaldihydroxamic acid as analytical reagent: Spectrophotometric determination of manganese

The reactivity of isophthaldihydroxamic acid against inorganic ions is established. The spectrophotometric study of its reaction with Mn(II) shows that a complex of stoichiometry 1:2 (Mn:L) is formed (? = 3760 liters · mol^?1 · cm^?1 at 490 nm). A spectrophotometric method is developed for the determination of manganese in the range 3–9 ppm.     

Mononuclear and homobinuclear vanadium(IV), chromium(III), molybdenum(III), and uranium(VI) chelates with ortho-cresolphthalein complexone

Mononuclear and homobinuclear o-cresolphthalein complexone complexes with VO²⁺, Cr³⁺, MoO⁺, and UO₂ ²⁺ have been prepared and their structures investigated. The empirical formulas, the mode of bonding, and the geometry of the complexes were obtained from elemental and thermal analyses, IR, electronic and ESR spectra, magnetic moment determinations, DC and CV polarographic studies.     

Potassium hexacyanoruthenate(II) as an analytical reagent for iron

Fe(III) undergoes a reaction with colourless Ru(CN)(4-)(6) to produce an intensely violet-blue complex that absorbs at 550 nm and obeys Beer's law over the iron concentration range 0.04-2 mug/ml in acidic medium. Some common cations and anions are tolerable at low concentrations. The procedure is applicable for determination of total iron in potable water. Destruction of organic matter is required for contaminated surface waters or soil samples.     

Trifluoroethylxanthate as an analytical reagent: Spectrophotometric determination of cobalt and copper as their trifluoroethylxanthates

Summary A direct spectrophotometric method has been developed for the micro-determination of Co(II) and Cu(II) as their trifluoroethylxanthates, by use of aqueous acetone medium. The reagent and methods have been found selective and sensitive for the determination of these metals in certain alloys.

---

Trifluorethylxanthat als analytisches Reagens: Spektrophotometrische Bestimmung von Kobalt und Kupfer

Zusammenfassung Eine direkte spektrofluorimetrische Methode zur Mikrobestimmung von Co(II) und Cu(II) in Form ihrer Trifluorethylxanthate in wäßrigem Acetonmedium wurde ausgearbeitet. Reagens und Methode sind bei der Bestimmung der genannten Metalle in gewissen Legierungen selektiv und empfindlich.

     

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.

---

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.

     

Simultaneous flow injection determination of iron(III) and vanadium(V) and of iron(III) and chromium(VI) based on redox reactions

A flow injection analysis (FIA) method is presented for the simultaneous determinations of iron(III)-vanadium(V) and of iron(III)-chromium(VI) using a single spectrophotometric detector. In the presence of 1,10-phenanthroline (phen), iron(III) is easily reduced by vanadium(IV) to iron(II), followed by the formation of a red iron(II)-phen complex (lambda(max) = 510 nm), which shows a positive FIA peak at 510 nm corresponding to the concentration of iron(III). On the other hand, in the presence of diphosphate the reductions of vanadium(V) and/or chromium(VI) with iron(II) occur easily because the presence of diphosphate causes an increase in the reducing power of iron(II). In this case iron(II) is consumed during the reaction and a negative FIA peak at 510 nm corresponding to the concentration of vanadium(V) and/or chromium(VI) is obtained. The proposed method makes it possible to obtain both positive (for iron(III)) and negative (for vanadium(V) or chromium(VI)) FIA peaks with a single injection.     

Rapid titrimetric methods for the determination of vanadium and molybdenum in mixtures

Summary A rapid and accurate method has been developed for the volumetric determination of molybdenum(VI) and vanadium(V) in mixtures, using cerium(IV) sulphate. In this procedure the sample solution is reduced in a mercury reductor (to give Mo^V and V^IV) and an aliquot of the reduced solution is titrated with Ce^IV solution using either ferroin, N-phenyl anthranilic acid, or barium diphenylamine sulphate as indicator. This titration gives the amount of molybdenum present, as V^IV does not interfere under the conditions applied. Another aliquot of the reduced solution is titrated with Ce^IV solution and rhodamine 6 G as indicator (observing the quenching of the fluorescence). This titration corresponds to the sum of molybdenum and vanadium. The vanadium content can be calculated by difference.

---

Zusammenfassung Zur schnellen und genauen volumetrischen Bestimmung von Molybdän(VI) und Vanadium(V) in Mischungen wird Cer(IV)-sulfat als Reagens verwendet. Die Probelösung wird im Quecksilberreduktor reduziert (wobei Mo^V und V^IV gebildet werden) und ein aliquoter Teil der reduzierten Lösung wird mit Ce^IV-Lösung titriert, wobei Ferroin, N-Phenylanthranilsäure oder Bariumdiphenylaminsulfonat als Indicator dient. Aus dieser Titration erhält man den Molybdängehalt, da V^IV unter den angewendeten Bedingungen nicht stört. Ein weiterer Teil der reduzierten Lösung wird mit Ce^IV-Lösung gegen Rhodamin 6 G titriert (Endpunkt durch Fluorescenzlöschung), woraus man die Summe Mo + V erhält. Der Vanadiumgehalt ergibt sich aus der Differenz.

     

2-Mercaptoquinoline (thiocarbostyril) as an analytical reagent for copper and palladium

Summary 2-Mercaptoquinoline is introduced as a sensitive and selective reagent for copper and palladium. Spot test detections and spectrophotometric determinations of these metals have been carried out. 0.03 g Cu at a limiting concentration of 1 430,000 can be detected by the spot technique on a filter paper, and 0.025 g Cu at a limiting concentration of 1 10⁶ by means of the spot plate method. Palladium was determined by measuring the optical density of the orange-yellow colour at 450 m developed in alcoholic medium at p_H 1.4–2.8. The sensitivity is 0.009 g Pd per cm² (Sandell).The author feels deeply indebted to Professor P. Rây, Director and Professor (Hony) of Inorganic Chemistry, for his helpful suggestions, and to Dr. P. C. Banerjee for his kind interest in the work.     

The simultaneous determination of vanadium,chromium, manganese,iron, cobalt,nickel, copper and zinc in sea water by x-ray fluorescence sectrometry

A procedure is described for the determination of microgram quantities of the elements vanadium, chromium, manganese, iron, cobalt, nickel, copper and zinc in sea water. Separation and concentration of these elements from a large salt matrix, in order to prevent interferences in the subsequent X-ray fluorescence spectrometry, is achieved by continuous solvent extraction. Ammonium pyrrolidine dithiocarbamate is used as a chelating agent, and the chelated trace elements are quantitatively extracted at a pH of ca. 2.5 into methyl isobutyl ketone. Detection limits of 0.14 μg or better are obtained when a 600-sec counting period is used for X-ray fluorescence spectrometry.     

Anion exchange separation of chromium and molybdenum from iron,vanadium, uranium and other elements in malonic acid solution

Summary Anion-exchange behaviour of chromium (III) and molybdenum (VI) was studied in malonate media. They form anionic complexes with malonic acid at pH 5.6. Various eluants, such as mineral acids and their salts were tested and a selectivity scale evolved. Cr and Mo were separated from Tl(I), alkali and alkaline earth elements by selective sorption and from Co(II), Ni(II), Mn(II), Zn(II) and Cd(II) by selective washing with water. They were separated from many other elements by selective elution. The sequential separation of Fe(III) V(IV), Cr(III), Mo(VI) and U(VI) was significant.     

Extractive separation of molybdenum as Mo(V) xanthate from Iron, vanadium, Tungsten, copper, uranium and other elements

A simple and selective extraction of molybdenum is described. Tungsten is masked with tartaric acid and molybdenum(VI) is reduced in 2M hydrochloric acid by boiling with hydrazine sulphate. Iron, copper and vanadium are then masked with ascorbic acid, thiourea and potassium hydrogen fluoride respectively. The molybdenum(V) is extracted as its xanthate complex into chloroform, from 1M hydrochloric acid that is 0.4M potassium ethyl xanthate. The complex is decomposed by excess of liquid bromine, and the molybdenum is stripped into alkaline hydrogen peroxide solution. The molybdenum is then determined by standard methods. Large amounts of Cu(II), Mn(II), Fe(III), Ti(IV), Zr, Ce(IV), V(V), Nb, Cr(VI), W(VI), U(VI), Re(VII) and Os(VIII) do not interfere. Several synthetic samples and ferromolybdenum have been rapidly and satisfactorily analysed by the method.