Acidity of several chromotropic acid azo derivatives

Both potentiometric and spectrophotometric methods have been used for the determination of the stability constants of hydrogen complexes of 4,5-dihydroxynaphthalene-2,7-disulphonic acid (Chromotropic Acid, CA), 3,6-bis(phenylazo)-4,5-dihydroxynaphthalene-2, 7-disulphonic acid (Azo III, A III), 3,6-bis(2'-sulphophenylazo)-4, 5-dihydroxynaphthalene-2,7-disulphonic acid (Sulphonazo III, SA III), 3,6-bis(4'-methyl-2'-sulphophenylazo)-4,5-dihydroxynaphthalene 2,7-disulphonic acid (Dimethylsulphonazo III, DMSA III), 3-(4'-chloro - 2' - phosphonophenylazo) -4,5- dihydroxynaphthalene -2,7-disulphonic acid (Chlorophosphonazo I, CPA I), 3,6-bis(4'-chloro-2'-phosphonophenylazo)-4,5-dihydroxynaphthalene-2,7-disulphonic acid (Chlorophosphonazo III, CPA III), 3-(2'-arsonophenylazo)-4, 5-dihydroxynaphthalene-2,7-disulphonic acid (Arsenazo I, AA I) and 3,6-bis(2'-arsonophenylazo)-4,5-dihydroxynaphthalene-2,7-disulphonic acid (Arsenazo III, AA III).     

Sorption of Lanthanum, Terbium, and Erbium Complexes of Some Mono- and Bisazoderivatives of Chromotropic Acid in the Presence of Surfactants

Optimal conditions were found for the sorption of lanthanum, terbium, and erbium complexes of some derivatives of chromotropic acid: Arsenazo II, Arsenazo III, Carboxyarsenazo, and Chlorophosphonazo III on Silochrom C-120 silica gel in the presence of tetrabutylammonium bromide (TBA). Diffuse reflection coefficients and molar coefficients of the chromaticity functions of the adsorbates were determined. It was demonstrated that the preconcentration of complexes on the solid matrix in the presence of TBA increases the sensitivity of the determination of rare-earth elements by a factor of 5–50 in comparison with solutions; the use of chromaticity characteristics further increases the sensitivity by 1.5–2 orders of magnitude.     

Comparative study of the masking effect of various complexans in the spectrophotometric determination of uranium with arsenazo III and chlorophosphonazo III

Results are presented for the masking of 35 elements with the complexans DTPA, EGTA and TTHA in the spectrophotometric determination of uranium(VI) with Arsenazo III at pH 1.8 +/- 0.2 and with Chlorophosphonazo III at pH 1.1 +/- 0.2. The complexans EDTA and DCTA were found to be less suitable because at low pH they tended to precipitate. DTPA is shown to be especially attractive for masking other elements in the determination of uranium(VI) at low pH.     

Effect of complexants on the adsorption and color reactions of lanthanum(III), uranium(VI), thorium(IV), and zirconium(IV) with Arsenazo M in the solid phase of an ANKB-50 fibrous ion-exchanger

The effect of complexants—acetic, aminoacetic, tartaric, malonic, and oxalic acids; EDTA; and Na₂CO₃—on the adsorption and subsequent determination of thorium(IV), lanthanum(III), uranium(VI), and zirconium(IV) with Arsenazo M in the solid phase of polyacrylonitrile fiber filled with an ANKB-50 anion exchanger was studied. Complexing agents were introduced into the solution at the step of metal ion adsorption. It was shown that zirconium and uranium interacted with the iminodiacetate groups of the adsorbent in the course of adsorption; the adsorption of elements from 10^?3 to 10^?2 M complexant solutions (except for tartaric and oxalic acids and EDTA) under the optimum conditions was enhanced as compared to their adsorption from pure solutions; complexation with Arsenazo M in the solid phase proceeded at a higher acidity than in the solution. When the elements were present simultaneously, their total concentration and individual thorium could be determined from malonic acid solutions with Arsenazo M by varying the concentration of acid and the adsorption pH.     

Thin-layer chromatographic separation of scandium, yttrium, the rare earths, thorium and uraniuin(VI)

The Chromatographic behaviour of scandium, yttrium, the rare earths, thorium and uranium(VI) in dioxan-hydrochloric acid and dioxan-nitric acid media on a plain cellulose thin layer has been investigated. The following separations are possible: scandium-yttrium-lanthanum, scandium-samarium-thorium, scandium-lanthanum-lutetium, yttrium-lanthanum-thorium, and lutetium-thorium-uranium(VI) with dioxan-12M hydrochloric acid (7:3) and scandium-samarium-thorium, scandium-yttrium-uranium(VI), lutetium-thorium, and scandium-lanthanum-thorium with dioxan-14M nitric acid (7:3). A single chromogenic spray (Arsenazo III) has been used for the detection of all the metal ions studied.     

Determination of the sum of rare-earth elements by flow-injection analysis with Arsenazo III, 4-(2-pyridylazo)resorcinol, Chrome Azurol S and 5-bromo-2-(2-pyridylazo)-5-diethylaminophenol spectrophotometric reagents

The reactivity of Arsenazo III, Chrome Azurol S in the presence of cetyltrimethylammonium or cetylpyridinium bromide, 4-(2-pyridylazo)resorcinol and 5-bromo-2-(2-pyridylazo)-5-diethylaminophenol with various rare-earth elements (REE) has been studied and the optimum conditions have been established for the spectrophotometric determination of REE with stationary and flow systems. Arsenazo III is the most suitable for the determination of the sum of REE, especially La, Ce, Nd, by FIA with spectrophotometric detection at 660 nm, in systems containing 0.04 mM reagent and 0.2M formate buffer (pH 3) and for sample volumes of 30 mul. The detection limits are 10.8 ng La, 11.0 ng Ce and 9.4 ng Nd in 30 mul. Limited amounts of Fe(III) and Al(III) are screened with 10 mM ascorbic and 5-sulphosalicylic acids. The sum of the REE is obtained from calibration plots prepared with La(III) standard solutions. The method has been successfully used for apatites and REE oxide concentrates after various kinds of decomposition.     

Anion-exchange system in magnesium nitrate media. Application to chemical analysis of manganese nodules for thorium and uranium

Summary The adsorption behaviour of 26 metal ions on the strongly basic anion-exchange resin Bio Rad AG-1, X-8 has been examined in magnesium nitrate media. The salt concentration range from 0.50-3.0 M is covered in the presence of 0.1 M free nitric acid. The distribution coefficients of bismuth(III), thorium(IV) and uranium(VI) rise to the order of 1,000 in media of 0.1 M nitric acid with high salt strength, while most other elements are only weakly adsorbed as is also the case in pure nitric acid media. The system allows thorium(IV) and uranium(VI) to be concentrated simultaneously from 2.5 M nitrate media, so that it can be applied successfully to the determination of thorium and uranium in manganese nodules with consecutive Chromatographic elution from a single small resin column. The subsequent determination is carried out spectrophotometrically with Arsenazo III.

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Anionenaustausch in Magnesiumnitratlösung. Anwendung zur Thorium- und Uranbestimmung in Manganknollen

Zusammenfassung Das Adsorptionsverhalten von 26 Metallionen wurde aus Magnesiumnitratlösung an dem stark basischen Anionenaustauscher Bio-Rad AG-1, X-8, untersucht. Die Salzkonzentration reichte von 0,5-3,0 M bei Gegenwart von 0,1 M freier Salpetersäure. Die Verteilungskoeffizienten von Bismut(III), Thorium(IV) und Uran(VI) reichen bei hoher Salzkonzentration bis zur Größenordnung von 1000, wogegen die meisten anderen Elemente nur schwach adsorbiert werden, was auch in reiner salpetersaurer Lösung der Fall ist. Dadurch können Th(IV) und U(VI) gleichzeitig aus 2,5 M Nitratlösung angereichert und mit gutem Erfolg in Manganknollen bestimmt werden, wobei nur eine einzige Elution von einer kleinen Harzsäule erforderlich ist. Die anschließende Bestimmung erfolgt spektralphotometrisch mit Arsenazo III.

     

Sorption and complexation of uranium(VI) and thorium(IV) with reagents Arsenazo III and Arsenazo M on fibrous filled sorbents

The possibility of the highly sensitive sorption-spectrometric determination of Th(IV) and U(VI) in the presence of each other on the solid phase of fibrous anion-exchange materials with Arsenazo M and Arsenazo III was examined. Polyacrylonitrile fiber filled with an exchanger AN-31, ANKB-50, or EDE-10p was used as the solid phase. It was demonstrated that the studied systems allow the selective determination of thorium in the presence of one-to twofold amounts of uranium. On PANV-EDE-10p with immobilized Arsenazo III, the detection limit of thorium in 2–10 M HCl is 0.002 μg/mL, and in 10 M HCl the presence of up to twofold amounts of uranium is permissible. A high sensitivity of the determination of uranium in 2–7 M HCl of 0.005 μg/mL, which has not been reported before, was attained. The time of the analysis of five or six samples is no longer than 20 min.     

Sorption-spectrometric determination of lanthanum in the presence of uranium and thorium with the reagent Arsenazo M on the solid phase of fibrous filled sorbents

The possibility of the determination of La(III) in the presence of U(VI) and Th(IV), a solid phase with the reagent Arsenazo M, was examined. It was demonstrated that the determination of lanthanum with Arsenazo M in 0.05 M HCl in the presence of 3-, 2-, 1-, and 10-fold amounts of U(VI), Th(IV), Zr(IV), and Ti(IV) is possible after sorption on polyacrylonitrile fiber filled an ion exchanger with iminodiacetate groups (PANV-ANKB-50). For sorption under the optimum conditions at pH 5, the detection limit of lanthanum is 0.01 μg/mL. The method for the determination of lanthanum was verified by the added-found method in the analysis of tap water. To decrease the matrix effect, it is recommended to perform sorption in the analysis of water at pH 2.5. In this case, the detection limit of La(III) is 0.02 μg/mL, RSD < 20%. The time of the analysis of 5 or 6 samples is no longer than 20 min.     

Spectrophotometric determination of zirconium, uranium, thorium and rare earths with arsenazo III after extractions with thenoyltrifluoroacetone and tri-n-octylamine

A method is described for the spectrophotometric determination of microgram amounts of zirconium, uranium(VI), thorium and rare earths with Arsenazo III after systematic separation by extraction. First zirconium is extracted into a xylene solution of thenoyltrifluoroacetone (TTA) from about 4M hydrochloric acid. Uranium(VI) is then extracted into a xylene solution of tri-n-octy lamine from about 4M hydrochloric acid. Thorium is next extracted into TTA solution at pH about 1.5, and finally rare earths are extracted into TTA solution at pH about 4.7. Each metal is back-extracted from the organic phase before determination.     

Sorption-spectroscopy and test determination of uranium(VI) and iron(III) from a single sample on the solid phase of fiber materials filled with an AB-17 ion exchanger

Diffuse reflectance spectroscopy has been used for the study of the sorption of malonate and glycolate complexes of uranium(VI) and iron(III), present simultaneously in solution, onto the solid phase of fiber materials filled with an AB-17 anion exchanger. In the form of malonate complexes uranium(VI) is determined in 0.5 M HCl on substrate discs with immobilized Arsenazo III, while iron(III) is determined on substrate discs with potassium thiocyanate in 0.5 M HCl. The dependence of the analytical signals on the concentrations of U(VI) and Fe(III) is linear in the ranges 0.02–0.16 μg/mL; the detection limit is 0.01 μg/mL. The possibility of analysis of U(VI) and Fe(III) mixtures in ratio from 1: 5 to 5: 1 in the presence of 2-fold concentrations of Zr(IV), Th(IV), and Ti(IV), 5-fold concentrations of Bi(III), 10-fold concentrations of Cu(II), 20-fold concentrations of La(III), 100-fold concentrations of Ni(II) and Zn(II), and 200-fold concentrations of Co(II) and Ca(II) has been demonstrated. Standard color scales in the concentration range from 0.02 to 0.2 μg/mL have been used for the visual determination of uranium(VI) and iron(III).     

Effect of arsenate and phosphate ions on the adsorption and complexation of uranium(VI) with Arsenazo III on the solid phase of the ion exchanger PAN-EDE-10p fibrous anion exchanger

The effect of arsenate and phosphate ions on the adsorption and color reaction of uranium(VI) with Arsenazo III on the solid phase of a fibrous material filled with the EDE-10p anion exchanger was studied in different adsorption processes. We selected the optimum conditions for the system of U(VI)-AsO ₄ ^3? (H₂PO ₄ ^? )-PANV-EDE-10p-Arsenazo III and used this system for the adsorption-spectrophotometric determination of (0.03–0.3) 10^?3 M arsenate, (0.004–0.06) 10^?3 M phosphate, and 0.01–0.1 μg/mL uranyl ions.     

Extractive photometric determination of plutonium(IV) with Aliquat-336 and xylenol orange

A rapid extractive photometric method using Aliquat-336 and xylenol organe for the determination of plutonium(IV) at μg levels has been developed. Quantitative extraction is obtained from ∼4M aqueous HNO₃ medium, affording estimation in the presence of several commonly occurring impurities, viz. iron, uranium, fission products and cladding materials. Effects of acidity, reagent concentration and diverse ions on the estimation have also been invetigated. Unlike the well-known absorptiometric method for determining plutonium(IV) employing Arsenazo III, the procedure presented here tolerates manyfold excesses of uranium(VI) as well as chromium(III), iron(III) and zirconium(IV), which are some of the major contaminants of plutonium during reprocessing.     

Solvent extraction separation of zirconium from malonate solution with high molecular-weight amines

Zirconium is quantitatively extracted with 4% Amberlite LA-1 or LA-2 in xylene, from 0.01 M malonic acid medium at pH 3.0 and stripped from the organic phase with 2M hydrochloric acid, then determined spectrophotometrically at 665 nm as its complex with Arsenazo III. Zirconium is separated from various other elements by selective extraction and stripping. The method has been applied to the analysis of zircon.     

Ion interaction chromatography of nitrilotriacetatocomplexes of the rare earth elements with post-column reaction detection

The chromatographic behaviour of nitrilotriacetatocomplexes of the rare earth elements (Sc, Y and lanthanides) on a reversed phase ODS column has been investigated in the presence of 1-octane-sulphonate. There is a great difference in selectivity for the ODS among the rare earth nitrilotriacetato-complexes. Concentration gradient elution with nitrilotriacetic acid (0.005-0.050M, pH 3.0) that contains 0.01M 1-octanesulphonate allows the rare earth elements to be separated from each other within 30 min at room temperature, except a Gd-Eu pair which is eluted together. Yttrium elutes at about 10 min between samarium and neodymium. Detection and quantitation of the rare earth elements can be achieved by post-column reaction with Chlorophosphonazo III in acid media at 700 nm.     

Simultaneous determination of uranium and plutonium at trace levels in process streams using Arsenazo III by derivative spectrophotometry

A derivative spectrophotometric method has been developed for the simultaneous determination of uranium and plutonium at trace levels in various process streams in 3M HNO₃ medium using Arsenazo III. The method was developed with the objective of measuring both uranium and plutonium in the same aliquot in fairly high burn-up fuels. The first derivative absorbances of the uranium and plutonium Arsenazo III complexes at 632 nm and 606.5 nm, respectively, were used for their quantification. Mixed aliquots of uranium (20–28 μg/ml) and plutonium (0.5–1.5 μg/ml) with U/Pu ratio varying from 25 to 40 were analysed using this technique. A relative error of about 5% was obtained for uranium and plutonium. The method is simple, fast and does not require separation of uranium and plutonium. The effect of presence of many fission products, corrosion products and complexing anions on determination of uranium and plutonium was also studied.     

Simultaneous determination of uranium and thorium with Arsenazo III by second-derivative spectrophotometry

A derivative spectrophotometric method has been developed for the simultaneous determination of microgram quantities of uranium and thorium with Arsenazo III in hydrochloric acid medium. The second-derivative absorbances of the uranium and thorium Arsenazo III complexes at 679.5 and 684.4 nm are used for their quantification. Uranium and thorium, both in the range 0.1-0.7 mug/ml have been determined simultaneously with good precision. The procedure does not require separation of uranium and thorium, and allows the determination of both metals in the presence of alkaline-earth metals and zirconium, but lanthanides interfere.     

Determination of uranium in technological waters by ion-pair liquid chromatography

U(VI) can be efficiently determined in the range 0.3-1OmM after its separation from Th(IV), Zr(IV), Al(III), Fe(III), lanthanides and other ions by ion-pair liquid chromatography on a 3 x 150 mm glass column packed with Separon SGX C18 modified with sorbed ammonium dodecyl sulphate. Traces of uranium can be preconcentrated directly on the analytical column from acidified water solutions and separated from Th, Zr, Al, Fe, lanthanides and other elements, with an enrichment factor of $ 100 and recovery of 98 +/- 8%, by isocratic or pH or concentration gradient elution with ammonium 2-hydroxy-2-methylpropionate or ammonium citrate solution. Post-column derivatization with 25muM Arsenazo III in 0.1M formate buffer at pH 2.7 is used for detection and quantification.     

A spectrophotometric method for the determination of neptunium and plutonium in process solutions

A method is described for the determination of neptunium and plutonium in process solutions. This involves the separation of these elements followed by their spectrophotometric determination as Arsenazo III complexes. Neptunium(IV) and plutonium(IV) are separated using TTA extraction method and the separated Np(IV) and Pu(IV) are then determined as their Arzenazo III complexes in 5M HNO₃. A few solutions obtained by dissolving irradiated fuels were analysed for plutonium and neptunium using this method and the results were compared with those obtained by other methods. An attempt was made to use Arsenazo III to determine uranium in the plant solutions.     

Determination of uranium in wet phosphoric acid

A method for quantitative determination of uranium in wet phosphoric acid containing 0.001-0.02% of uranium has been developed. After reduction with Fe or FeSO(4) . H(2)O, uranium(IV) is extracted with a kerosene solution of an equimolar mixture of mono- and dinonylphenylphosphoric acids. The uranium is stripped with an oxidizing medium consisting of 10M H(3)PO(4) containing NaClO(3). The uranium stripped is determined spectrophotometrically with Arsenazo III.