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.     

A spectrophotometric method for the determination of plutonium in fuel solutions

A spectrophotometric method is described in which microgram amounts of plutonium can be determined in the presence of uranium, thorium, fission products and cladding materials. Plutonium is extracted with TTA in xylene and reextracted into a solution of Arsenazo III. Zirconium is masked by a Fe(III)-EDTA mixture, fluoride ions by Al(III). 2 to 40 μg of plutonium are required for one analysis. The standard deviation is 1.3% at 15 μg plutonium.     

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.     

A ratio derivative spectrophotometric method for the simultaneous determination of uranium and plutonium

A ratio derivative spectrophotometric method has been developed for the simultaneous determination of uranium and plutonium at mg levels in 1M HNO₃ medium. In this method the overlapping spectra of uranium and plutonium are well resolved by making use of the first derivative of the ratios of their direct absorption spectra. The derivative ratio absorbances of uranium and plutonium are measured at 411.2 and 473.8 nm, respectively for their quantification. The method is simple, fast and does not require separation of uranium and plutonium. Another salient feature of the method is that it does not lead to generation of analytical waste thereby minimising the efforts required for the recovery of plutonium. Uranium in the conc. range of 10–25 mg/g and plutonium in the conc. range of 0.5 to 2 mg/g (U/Pu ratio varying from about 10 to 25) were determined in the same aliquot with a precision and accuracy of about 0.5% and 1%, respectively.     

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.     

On atomization of uranium in plutonium matrix using ETA-AAS

Atomization processes for uranium in aqueous media and in the presence of a plutonium matrix have been studied and a chemical mechanism is proposed. These studies have been utilized for the determination of uranium in plutonium by Electrothermal Atomization- Atomic Absorption Spectrometry (ETA-AAS) within the constraints of its stable carbide forming tendency and complexity caused by formation of plutonium suboxide at high temperatures. In spite of these limitations the analytical range obtained for determination of uranium is 2.5–100 ng with a sample aliquot of 5 μL containing 5 mg/mL plutonium concentration. The precision of the method is evaluated as 9% RSD. Received: 9 September 1997 / Revised: 29 December 1997 / Accepted: 31 December 1997     

Sorption-spectrometric determination of thorium(IV) and uranium(VI) with the reagent Arsenazo III on the solid phase of a fibrous material filled with a cation exchanger

The possibility of the use of organic reagents of the Arsenazo III group for the sorption-spectrometric determination of elements on fibrous cation-exchange materials was examined. The conditions of the sorption of Arsenazo III with the use of diphenylguanidinium chloride on the strongly acidic fibrous cation exchanger PANV-KU-2 were found. Procedures for the determination on the solid phase were developed for thorium in 7 M HNO₃ in the presence of 30-fold amounts of uranium with the detection limit of thorium of 0.005 μg/mL and for uranium in 0.05 M HCl in the presence of fivefold amounts of thorium with a detection limit of uranium of 0.05 μg/mL. The conditions were found for the selective preconcentration of thorium and uranium in the presence of each other, and a procedure was developed for their separate sorption-spectrometric determination.     

Extraction and spectrophotometric determination of uranium in phosphate fertilizers

An extraction and spectrophotometric method for determination of trace amounts of uranium in phosphate fertilizers is described. It is based on the extraction of uranium with trioctylphosphine oxide in benzene and the spectrophotometric determination of uranium with Arsenazo III in buffer-alcoholic medium. The maximum absorbance occurs at 655 nm with a molar absorptivity of 1.2·10⁴ l·mol^–1·cm^–1. Beer's law is obeyed over the range 0.6–15.0 g·ml^–1 of uranium(VI). The proposed method has been applied successfully to the analysis of phosphate fertilizers with phosphate concentrations of 45% P₂O₅.     

Spectrophotometric Determination of Some Phenolic Antibiotics in Dosage Forms

 A simple and sensitive spectrophotometric method is described for the determination of some phenolic antibiotics namely: cefadroxil, amoxicillin and vancomycin. The method is based on the measurement of the orange yellow species produced when the drugs are coupled with diazotized benzocaine in triethylamine medium. The method is applicable over the range of 0.8–12 μg/ml for cefadroxil, 2–16 μg/ml for amoxicillin and 2–18 μg/ml for vancomycin. The formed compounds absorb at 455 nm for both cefadroxil and amoxicillin and at 442 nm for vancomycin. The proposed method has detection limits of 0.018 μg for cefadroxil, 0.0034 μg for amoxicillin and 0.0156 μg for vancomycin. The stoichiometric ratio for the studied compounds was found to be 1:1 and a proposal of the reaction pathway was made. The proposed method was applied for the analysis of the cited drugs in their pharmaceutical preparations. The results are in good agreement with those obtained by the official methods. Received February 7, 2000. Revision June 14, 2000.     

Determination of uranium and plutonium in VVER spent fuel solutions using differential spectrophotometry

The method of differential spectrophotometry with the use of Arsenazo III for uranium determination with masking Zr and Pu by 1,2-diaminecyclohexanetetraacetic acid in acetate buffer and carboxyarsenazo for determination of plutonium without its separation from uranium is applied for analysis of the spent fuel of VVER type reactors.     

Sensitive spectrophotometric determination of ascorbic acid in fruit juices and pharmaceutical formulations using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Br-PADAP)

A simple and very sensitive method has been developed for the determination of ascorbic acid based on the oxidation of ascorbic acid to dehydroascorbic acid by iron(III), followed by a complexation of iron(II) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol(Br-PADAP). The iron(II) complex is formed immediately, with absorption maxima at 560 and 748 nm and a molar absorptivity of 1.31 × 10⁵ l mole^–1cm^–1 and 5.69 × 10⁴ l mole^–1cm^–1, respectively. The ascorbic acid determination is possible with a linear range up to 2.4 μg ml^–1, a calibration sensitivity of 0.744 ml μg^–1 at 560 nm and 0.323 ml μg^–1 at 748 nm, and a detection limit of 15 ng ml^–1 and 44 ng ml^–1, respectively. The procedure was used for the ascorbic acid determination in several fruit juices and pharmaceutical formulations. The results demonstrated a good precision (R.S.D. < 1%) and are in agreement with those obtained with others methods. The Br-PADAP method proposed is six times more sensitive than the method using the iron(II)-1,10-phenanthroline system. Received: 7 May 1996 / Revised: 1 July 1996 / Accepted: 8 August 1996     

Sensitive spectrophotometric determination of ascorbic acid in fruit juices and pharmaceutical formulations using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Br-PADAP)

A simple and very sensitive method has been developed for the determination of ascorbic acid based on the oxidation of ascorbic acid to dehydroascorbic acid by iron(III), followed by a complexation of iron(II) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol(Br-PADAP). The iron(II) complex is formed immediately, with absorption maxima at 560 and 748 nm and a molar absorptivity of 1.31 × 10⁵ l mole^–1cm^–1 and 5.69 × 10⁴ l mole^–1cm^–1, respectively. The ascorbic acid determination is possible with a linear range up to 2.4 μg ml^–1, a calibration sensitivity of 0.744 ml μg^–1 at 560 nm and 0.323 ml μg^–1 at 748 nm, and a detection limit of 15 ng ml^–1 and 44 ng ml^–1, respectively. The procedure was used for the ascorbic acid determination in several fruit juices and pharmaceutical formulations. The results demonstrated a good precision (R.S.D. < 1%) and are in agreement with those obtained with others methods. The Br-PADAP method proposed is six times more sensitive than the method using the iron(II)-1,10-phenanthroline system. Received: 7 May 1996 / Revised: 1 July 1996 / Accepted: 8 August 1996     

Determination of glimepiride in pharmaceutical formulations using HPLC and first-derivative spectrophotometric methods

Two validated analytical methods have been developed to determine glimepiride in pharmaceutical formulations using HPLC and 1st order derivative spectrophotometric techniques. Employing reverse phase HPLC method, the drug was analyzed by pumping a mixture of acetonitrile and 2% formic acid solution, pH 3.5 (80: 20 v/v) through a C₁₈ column (250 × 4.6 mm, 5 μm) and detecting the eluents at 228 nm. The linearity range was found to be 20–140 μg/mL with mean recovery of 100.52 ± 0.33%. The second method was based on the formation of a complex of the drug with 2,3,5-triphenyl-2H-tetrazolium chloride in basic media. 1st order derivative spectrum made it possible to detect the complex at 413.5 nm. The linearity range was found to be 40–160 μg/mL, with mean recovery of 100.33 ± 0.47%. Both the proposed methods can reliably be used for routine analysis of glimepiride in raw material as well as in pharmaceutical formulations. The article is published in the original.     

Determination of potential degradation products of piroxicam by HPTLC densiometry and HPLC

Summary HPTLC densitometry and HPLC are considered for the simultaneous determination of the degradation products of piroxicam (2-aminopyridine, DP-I and DP-II). The substances were separated on silica gel with fluorescence indicator in ethylacetate — toluene — diethylamine (10∶10∶5) and toluene — absolute ethanol — glacial acetic acid (8∶1.2∶0.5) systems. The measuring absorbance (detection of reflectance) of the separated substances was carried out “in situ” at 296 nm using 4-level calibration (external standard, nonlinear regresson function) in the concentration range 600–1200 ng 2-aminopyridine/spot and 300–600 ng DP-I and DP-II/spot. The HPLC method was carried out using RP-8 stationary phase and methanol + phosphate-citrate buffer, pH 3 mobile phase with addition of sodium pentanesulfonate (40+60, v/v). 2-aminopyridine wass detected at 300 nm, DP-I at 280 nm and DP-II at 248 nm. The concentration range for 2-aminopyridine is 2–40 μg/ml, for DP-I and DP-II 2–20 μg/ml (for an injection volume of 10 μl). The results were evaluated by linear regression analysis.     

Flow injection spectrofluorimetric determination of iron(III) in water using salicylic acid

A simple and fast flow injection fluorescence quenching method for the determination of iron in water has been developed. Fluorimetric determination is based on the measurement of the quenching effect of iron on salicylic acid fluorescence. An emission peak of salicylic acid in aqueous solution occurs at 409 nm with excitation at 299 nm. The carrier solution used was 2 × 10⁻⁶ mol L⁻¹ salicylic acid in 0.1 mol L⁻¹ NH₄⁺/NH₃ buffer solution at pH 8.5. Linear calibration was obtained for 5–100 μg L⁻¹ iron(III) and the relative standard deviation was 1.25 % (n = 5) for a 20 μL injection volume iron(III). The limit of detection was 0.3 μg L⁻¹ and the sampling rate was 60 h⁻¹. The effect of interferences from various metals and anions commonly present in water was also studied. The method was successfully applied to the determination of low levels of iron in real samples (river, sea, and spring waters).     

Solid-phase fluorometric determination of Al(III), Be(II), and Ga(III) using dynamic preconcentration on reagent cellulose matrix

A fluorimeter is developed, which provides sample pretreatment, preconcentration of analytes from natural waters on the surface of indicator cellulose matrices, and the simultaneous measurement of their fluorescence. The device employs a L-711UVC ultraviolet light diode and a Digital color sensor S9706 photodiode, which registers simultaneously in the red (615 nm), green (540 nm), and blue (465 nm) spectrum regions. The opportunities of the application of this fluorimeter have been shown by an example of determination of 1–100 μg/L Al(III) and 0.1–10 μg/L Be(II) and Ga(III).     

Determination of uranium(VI) in seawater by ion-exchanger phase absorptiometry with arsenazo III

An ion-exchange phase absorptiometric method with Arsenazo III has been developed for the determination of uranium (VI). A flow cell with 0.1 ml of anion exchange resin was employed to achieve a detection limit for uranium of 0.16 microg/l. in 100 ml of a seawater sample. The sensitivity is about 300 times higher than for corresponding solution spectrophotometry.     

Sorption-fluorimetric determination of zinc

The sorption of ions of zinc on carriers modified by 8-oxychinoline and its derivative is investigated. The optimum parameters of sorption are revealed, based on which silochrome S-60 with immobilized 8-oxychinoline (pH 7.1, time of contact 30 min, weight of sorbent 0.3 g, capacity of sorbent on the modifier 60 μmol/g) is chosen. A yellow-green fluorescence sorbate arises on irradiation by ultra-violet light in a phase sorbent. The spectrum of fluorescence represents a wide unstructured strip with a maximum at 505 nm. In the construction of a calibrated graph, Cu(II), Cd(II), Pb (II), Bi(III), and Fe(III) do not prevent the determination of 5–50 μg of zinc; however, equal amounts of Al(III) (50–100 μg) do prevent it. The technique is applied for the sorption-fluorimetric determination of zinc in river and waste water. The relative standard deviation does not exceed 0.05 (n = 5).     

Hochselektive spektralphotometrische Spurenbestimmung von Uran(VI) mit Arsenazo III nach Extraktionstrennung

Zusammenfassung Es wurde eine einfache, vielseitig anwendbare spektralphotometrische Uranbestimmung für U⁶⁺-Mengen bis in den ng-Bereich ausgearbeitet, bei der über 60 Kationen und etwa 20 Anionen in weiten Grenzen nicht stören. Das mit Triphenylarsinoxid in CHCl₃ aus der zu untersuchenden Lösung extrahierte Uran wird mit oxalsäurehaltiger 5,5 M HClO₄ zurückextrahiert und in den Arsenazo III-Komplex überführt. Die mit diesem Schritt verbundene Aufkonzentrierung erlaubt noch bis zu 0,01 g Uran in 200 ml Ausgangslösung spektralphotometrisch bei 655 nm zu bestimmen. Im günstigsten Arbeitsbereich beträgt die relative Standardabweichung ±1%. 4 Probelösungen können in 1 h analysiert werden.

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Highly selective spectrophotometric trace determination of uranium(VI) by arsenazo III, following purification and concentration by extraction

Summary A simple and versatile spectrophotometric method for the determination of uranium down to the g range was worked out. About 60 cations and 20 anions were found not to cause interferences in a wide concentration range. U⁶⁺ is extracted with triphenylarsine oxide in chloroform, back-extracted with 5.5 M perchloric acid containing oxalic acid and converted to the arsenazo III-complex. The concentration step involved allows the spectrophotometric determination of 0.01 g of uranium in 200 ml of original solution at 655 nm. A standard deviation of ±1 % can be achieved and it is possible to analyse about 4 solutions per hour.

Für die Überprüfung des Manuskriptes möchte ich den Herren Dr. P. Baertschi und O. Antonsen herzlich danken.     

Sorption-luminescence determination of gold,silver, and platinum with the use of silica gel chemically modified with <Emphasis Type="Italic">N</Emphasis>-(1,3,4-thiodiazole-2-thiol)-<Emphasis Type="Italic">N</Emphasis>′-propylurea groups

Silica gel chemically modified with N-(1,3,4-thiodiazole-2-thiol)-N′-propylurea extracted gold(III) from solutions in the range of 6 M HCl-pH 8 and silver(I) from nitric acid solutions in the range of 6 M HNO₃-pH 8 and 1–2 M HCl at 20°C with 99.0–99.9% recovery and a sorption equilibration time of 5 min. Platinum(II) was quantitatively extracted at room temperature from solutions in the range of 4 M HCl-pH 8; the sorption equilibration time was 20 min. For the quantitative extraction of platinum(IV), it should be reduced to platinum(II). The intense yellowish orange luminescence (λ_max (Au) = 575 nm, λ_max (Ag) = 550 nm, and λ_max(Pt) = 620 nm) of surface complexes at 77 K under UV irradiation was used in the development of procedures for the low-temperature sorption-luminescence determination of gold, silver, and platinum. The detection limits were 0.15 (Au), 0.1 (Ag), and 0.05 μg (Pt) per 0.1 g sorbent. The calibration function was linear to 50 (Au, Ag) or 80 μg (Pt) per 0.1 g sorbent. The relative standard deviation in the determination of more than 5 μg of a metal was no higher than 6%. The sorption-luminescence determination procedures were tested in the determination of gold in gold-containing concentrates and their processing products and platinum in alumina-platinum catalysts.