A new volumetric method for the determination of molybdenum(VI)

Summary A new volumetric method has been developed for the determination of molybdenum(VI). The method consists in the reduction of molybdenum(VI) by heating with a slight excess of hydrazine sulphate in 1 to 2 M hydrochloric acid medium for ten minutes on a water bath. The mixture is cooled and the molybdenum(V) obtained determined by titration with a standard solution of ceric sulphate at an overall acidity of 4 N hydrochloric acid, using diphenyl benzidine as indicator and adding 5 ml of syrupy phosphoric acid for 50 ml of the mixture. Alternately the molybdenum(V) can be titrated with a standard solution of ceric sulphate at an overall acidity of 3 N hydrochloric acid using ferroin as indicator and adding 5 ml of syrupy phosphoric acid for 50 ml of the titration mixture. The molybdenum(V) can also be titrated with a standard solution of sodium vanadate in 8 N sulphuric acid medium, using N-phenyl anthranilic acid as indicator. Alternately, the titration with sodium vanadate can be made with diphenyl benzidine as indicator in 4 N acid medium, adding 5 ml of syrupy phosphoric acid and 1 ml of 1.0 M oxalic acid to catalyse the indicator action. The method now proposed is much more convenient than the methods currently available. It is simple because it does not require any costly chemicals or complicated apparatus. Furthermore, it has the advantages of great rapidity and excellent precision.     

Colorimetric determination of uranium(VI)

A new, very sensitive reagent is proposed for the colorimetric determination of uranium(VI), namely 1-phenyl-3-methyl-4-(3'-carboxy-4'-hydroxyphenyl-azo)-pyrazol-5-one.     

Optode for uranium(VI) determination in aqueous medium

A quantification procedure of trace elements during colloid size fractionation was developed and validated. This procedure is based on the hyphenation between Asymmetrical Flow Field-Flow Fractionation (As-Fl-FFF) and Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The optimisation of the procedure was performed on a soil leachate spiked with six trace elements selected for their environmental and health impact (As, Cd, Sb, Se, Sn and Pb). The elements in the spiked sample were on-line monitored during the fractionation. The validation was carried out by comparison with a second off-line quantification procedure based on fraction collection and total element analysis by ICP-MS. This off-line one was previously validated using reference materials. Finally, the analytical performances of the two procedures were compared.     

A europium (III) complex-based surface fluorescence sensor for the determination of uranium (VI)

Journal of Radioanalytical and Nuclear Chemistry - In this paper, we report a method for the determination of uranium (VI) based on the using of a surface fluorescence sensor containing a europium...     

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.     

4-(21-thiazolylazo) resacetophenone oxime. A new analytical reagent for the spectrophotometric determination of uranium (VI)

4-(2¹-Thiazolylazo) resacetophenone oxime forms a pink colored soluble complex with uranium(VI) in buffer solutions of pH 6.0. The colored complex has a maximum absorbance at the wavelength 572 nm and the color is stable for about 48 h. The system obeys Beer's law over the concentration range 0.2–6.0 g of uranium cm^–3. The molar absorptivity and the Sandell sensitivity of the complex are 6.2×10⁴ dm³.mol^–1.cm^–1 and 0.0038 g cm^–2, respectively. Effect of various diversions has been studied and the method was successfully applied for the determination of uranium in rock samples.     

Further development in the high-precision volumetric method for the determination of uranium in nuclear-grade uranium compounds

The high-precision uranium determination by reduction with ferrous sulfate in phosphoric acid and titration with dichromate, which is applicable to nuclear-grade uranium compounds in which the uranium exists nearly exclusively as U(IV), has been modified. The modification enlarges the range of applicability of the original method to include the analysis of uranium compounds in which the uranium exists as U(VI) or as a mixture of U(IV) and U(VI), such as U₃O₈. The modified method has the same precision, relative freedom from interferences and applicability for routine use as the original method.     

Spectrophotometric determination of uranium(VI) with benzoylacetanilide

Ohne Zusammenfassung

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Use of complex forming substitution reactions for the selective enthalpiometric determination of cations and anions

     

Solvent extraction and spectrophotometric determination of uranium (VI)

Summary Solvent extraction of uranium-sodium diethyldithiocarbamate with ethylmethyl ketone and separation from titanium, zirconium, thorium, lanthanum and cerium has been described. It has been found that 11.75 to 47.00 mg of uranium can be extracted from a binary mixture containing 4.78 to 19.04 mg of titanium, 9.12 to 36.48 mg of zirconium, 116.0 to 460.0 mg of thorium, 6.95 to 27.8 mg of lanthanum or 7.06 to 28.24 mg of cerium at pH 3.0. The pH range between which the separations may be carried out successfully is 2.0 to 3.5. The following cations interfere in the separations: Cu^II, Fe^III, Co^II, Bi^III, Ni^II, Cr^VI, Te^IV, Se^IV, Ag^I, Hg^II, As^III, Sn^IV, Pb^IV, Cd^II, Mo^VI, Mn^II, V^V, Zn^II, In^III, Tl^I, W^VI, Os^VIII and Nb^V.

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Zusammenfassung Uran kann durch Extraktion als Diäthyldithiocarbamidat mit Methyläthylketon von Ti, Zr, Th, La oder Ce getrennt werden. Der günstigste pH-Bereich liegt zwischen 2,0 und 3,5. Die Trennungen wurden mit folgenden Mengen durchgeführt: U (11,75–47,00 mg); Ti (4,78 bis 19,04 mg), Zr (9,12–36,48 mg) Th (116,0–460,0 mg), La (6,95–27,8 mg), Ce (7,06–28,24 mg). Folgende Ionen verursachen Störungen: Cu^II, Fe^III, Co^II, Bi^III, Ni^II, Cr^VI, Te^IV, Se^IV, Ag^I, Hg^II, As^III, Sn^IV, Pb^IV, Cd^II, Mo^VI, Mn^II, V^VI, Zn^II, In^III, Tl^I, W^VI, Os^VIII sowie Nb^V.

     

An automatic spectrophotometric method for the determination of uranium(VI) extracted into a liquid ion-exchanger medium

An earlier procedure based on 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol is adapted for use with a Technicon AutoAnalyzer; 60 samples per hour can be analyzed. The range is 0.2–3 g of uranium per litre of extract. The method is readily modified for the determination of uranium (?200 μg l^-1) in ground waters.     

Spectrophotometric determination of uranium(VI) with 3-thianaphthenoyltrifluoroacetone

Summary Two visible spectrophotometric methods are described for the determination of uranium(VI) with 3-thianaphthenoyltrifluoroacetone at aph of 6.0. The effect due toph, time, solvents, reagent concentration and diverse ions are reported. Beer's law is obeyed in both cases and the molar extinction coefficients at 408 and 446 nm are 1.7·10⁴ and 2.3·10³ respectively.

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Zusammenfassung Zwei spektrophotometrische Methoden zur Bestimmung von U(VI) mit 3-Thianaphthenoyltrifluoraceton bei ph 6,0 wurden beschrieben. Der Einfluß vonph, Zeit, Lösungsmitteln, Reagenskonzentration und verschiedenen Fremdionen wurde angegeben. Das Beersche Gesetz wird in beiden Fällen befolgt. Der molare Extinktionskoeffizient bei 408 bzw. 446 nm beträgt 1,7 · 10⁴ bzw. 2,9 · 10³.

     

A volumetric method for the determination of sulphoxides

Summary A volumetric method for the quantitative determination of Sulphoxides has been developed, based on their oxidation to sulphones by dichromate in presence of 5 M sulphuric acid at 105–110°C. Excess dichromate is titrated by ferrous ammonium sulphate solution. The method is also applicable to the determination of Sulphoxides in metal sulphoxide complexes.

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Zusammenfassung Zur Bestimmung von Sulfoxiden wurde ein volumetrisehes Verfahren ausgearbeitet, das auf der Oxydation zu Sulfonen mit Hilfe von Dichromat in Gegenwart von 5 M Schwefelsäure (105–110°C) beruht. Der Überschuß an Dichromat wird mit Eisen(II)-ammoniumsulfatlösung zurücktitriert. Der Verfahren eignet sich auch zur Sulfoxidbestimmung in Metallsulfoxidkomplexen.

     

A new procedure for the spectrophotometric determination of uranium(VI) in the presence of a large excess of thorium(IV).

Spectrophotometric determination of microgram amounts of U(VI) with 2-(5-Bromo-2-Pyridylazo)-5-diethylaminophenol (Br-PADAP), originally developed by Johnson and Florence has been modified to enable the determination of U(VI) in the presence of a large excess of Th(IV). The effects of thorium, tri-n-butyl phosphate (TBP) and ethanol on the estimation of uranium have been studied in detail and are presented in this paper. This modified method can be applied for the analysis of U(VI) both in aqueous and organic samples containing a large excess of Th(IV) (Th:U = 10000:1).     

Extraction and spectrophotometric determination of uranium(VI) withN-phenylcinnamohydroxamic acid

Uranium(VI) reacts withN-phenylcinnamohydroxamic acid to form an orange-yellow complex in the pH range 5.5–8.5. The orange-yellow complex, having the composition of 12 (metal:ligand), is quantitatively extractable into ethyl acetate. The spectrum of the complex exhibits a maximum absorption at 400 nm with a molar absorptivity of 6500 M^–1·cm^–1. The coloured system obeys Beer's law in the concentration range 2–40g·ml^–1 of uranium(VI). The photometric sensitivity of the colour reaction is 0.037 g·cm^–2 of uranium(VI). Most of the common ions do not interfere and the method has been found to be simple, precise, and free from the rigid control of experimental conditions. The method has been applied to the determination of uranium in synthetic matrices and potable water.     

Extraction-spectrophotometric determination of uranium(VI) with PAR and N-octylacetamide

A new and simple method for selective spectrophotometric determination of uranium(VI) with 4-(2-pyridylazo)resorcinol (PAR) and N-octylacetamide into benzene over pH 7.0–9.0 is described. The molar absorptivity of the complex with 9 different amides is in the range of (0.40–3.2)·10⁴ 1·mol^–1·cm^–1 at the absorption maximum. Out of these, the most sensitive compound N-octylacetamide (OAA) was chosen for detailed studies in the present investigation. The detection limit of the method is 0.008 g U·ml^–1. The system obeys Beer's law in the range of 0–5 g U·ml^–1. The method is free from interferences of most of the common metal ions except vanadium(V) and copper(II), which are masked by proper masking agents. The composition of the complex is determined by curve-fitting method. The method has been applied for the recovery of the metal from rock samples and synthetic mixtures.     

A sensitive spectrophotometric method for the determination of trace amounts of uranium(VI) using 2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone

The reaction between uranium(VI) and 2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone (2HNAINH) has been investigated in HCl-sodium acetate buffers and a highly sensitive and simple procedure for the determination of uranium(VI) is suggested. The orange red colored complex showed maximum absorption at 430 nm in buffer solutions of pH 3. Beer's law is obeyed in the range of 0.2 to 33 g ml^–1. The molar absorptivity and Sandell's sensitivity are found to be 9.6×10³ mol·l^–1 and 0.025 g cm^–2, respectively. The composition of the complex between metal and reagent is found to be 11. The effect of diverse ions is also studied and the method is successfully applied for the determination of uranium in synthetic mixtures.