Comparative study on γ-radiolysis and energy transfer reaction induced by γ-irradiated NaCl in Methyl Orange and Methyl Red

A comparative study on -radiolysis and energy transfer reaction induced by -irradiated sodium chloride in azo-dye indicators, viz. Methyl Orange and Methyl Red are undertaken. These indicators undergo degradation following first order kinetics, the determined rate constants being 1.05·10^–8 rad^–1 for Methyl Orange and 5.00·10^–7 rad^–1 for Methyl Red, respectively. TheG-values are also determined and are found to be lower for Methyl Orange (8.60·10^–6) and higher for Methyl Red (4.05·10^–3), suggesting that the former is more resistent to radiation degradation as compared to the latter.     

Determination of neptunium in plutonium and mixed uranium-plutonium samples by isotope dilution gamma-spectrometry with243Am as a spike

A method was developed for isolating neptunium from Pu, U or mixed oxide (MOX) samples and its determination by isotope dilution -spectrometry (IDGS) using²³⁹Np (²⁴³Am) as a spike. Extraction chromatography with trilaurylamine fixed on a SGX-C18 support was used for the isolation of Np. The decontamination factors for U, Pu, Am and Pa vary between 1000–2000 and 100, respectively. The average separation yield of Np is (95±3)%. The amount of²⁴³Am required for spiking is about 0.2–0.3 g. It is recommended to use the pair of -rays 86.53 keV (²³⁷Np)-106.13 keV (²³⁹Np) for the assay of neptunium. A relative uncertainty of 4% or better is achievable in the analysis of plutonium samples, containing 0.4–80 g neptunium. The detection limit, under the proposed experimental conditions, is about 0.05 g Np. The results were compared with the results obtained by using high resolution -spectrometry (HRGS).     

Low level measurements of thorium and neptunium in environmental samples using the (γ, f) reaction

A new highly sensitive track method for the determination of thorium (²³²Th) and neptunium (²³⁷Np) has been developed. The technique includes the radiochemical separation procedure of the isotopes followed by the irradiation of the resultant samples on the MT-25 microtron. The detection limit is équivalent up to 3·10^–13 g of²³²Th and 7·10^–14 of²³⁷Np. The method was used to determine²³²Th and²³⁷Np isotopes in water samples.     

Determination of sub-PPB contents of uranium and thorium in high-purity aluminium by RNAA

Aluminium samples, irradiated in a reactor, are dissolved in nitric acid²³³Pa and²³⁹Np are adsorbed on an anion exchange column and then separately eluted. The neptunium fraction is very pure and can be counted in a liquid scintillation counter with 100% efficiency. From the other fraction protactinium is extracted by trioctylphosphine oxide and measured by -ray spectrometry. With samples of 3 g, a thermal flux of 3·10¹³ n cm^–2s^–1 and an irradiation time of 24 hours detection limits are 0.0005 ng/g for U and 0.01 ng/g for Th.     

A study by pulse radiolysis of the radiation-chemical transformation of aqueous solutions of hydrazine in the presence of oxygen

It is shown by pulse radiolysis that in aqueous solutions of hydrazine containing oxygen the radical N₂H₃ reduces oxygen to O₂ ^– at pH > 7 (k 3·10⁹ dm³· mole^–1·sec^–1), while this reaction does not occur for the protonated form N₂H₄ ⁺ at pH < 7 (k, 5·10⁶ dm³·mole^–1·sec^–1). The rate constants for the disappearance of O₂ ^– have been determined in the pH range from 4 to 12. Rate constants have been calculated for the reaction of O^– with N₂H₄ [k=(1.6 ±0.2)·10⁹ dm³·mole^–1·sec^–1] and of O₃with N₂H₄ [k=(1.2 ±0.2)·10⁶ dm³· mole^–1·sec^–1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 341–345, February, 1991.     

Reversible sorption of hydrogen by colloidal palladium in aqueous solutions

Colloidal palladium was prepared by -irradiation or by H₂ reduction of Pd(NH₃)₄l₂ in aqueous solutions containing sodium polyacrylate as a stabilizer. The sots contain spherical particles 2–4 nm in diameter. Their optical spectra contain a band at 230 nm ( = 6.1 · 10³ L mol^–1 cm^–1) smoothly descending toward the visible range. The sots reversibly absorb chemically from 0.35 to 0.15 g-mol of H₂ per g-atom of Pd. The spectra of ultrafine metal particles saturated with molecular hydrogen exhibit an absorption band at 265 nm ( = 4.5 · 10³ L mol^–1 cm^–1). One-electron reduction of methylviologen by hydrogen is catalyzed by the colloidal palladium prepared.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 313–316, February, 1996.     

Immobilization of Urease and Cholinesterase on the Surface of Semiconductor Transducer for the Development of Light-Addressable Potentiometric Sensors

Various methods for the immobilization of urease and butyrylcholinesterase on the insulator surface of a laser-scanned semiconductor transducer (LSST) have been tested and compared for the development of an enzyme-based light-addressable potentiometric sensor (LAPS). The method of preparing photocurable membranes on LAPS is presented, and a new type of enzyme LAPS with photocurable polymeric enzyme membranes has been elaborated. It was found that sensors prepared by means of covalent bonding and cross-linking with inactive protein (type SIII) and with photocurable membrane matrices (type SIV) are more prospective. The enzyme LAPSensors with photocurable membranes demonstrate a degree of sensitivity close to the theoretical value and working ranges of 6.3·10^–5–1.1·10^–2 and 1·10^–4–1·10^–1molL^–1 urea for acrylamide and acrylate-based membrane matrices, respectively, and 2.5·10^–4–2·10^–1molL^–1 butyrylcholine for an acrylamide membrane matrix. It is shown that such sensors can be also used for the analysis of enzyme inhibitors.     

The use of3H- and14C-labelled tyrosines and product analysis to measure the mono- to diiodination rate constant ratio for iodination by molecular iodine and chloramine-T/I−

The observed rate constant ratio,^k ₁obs/^k ₂ obs, for the sequential iodination of L-tyrosine was determined in the concentration range 1.84·10^–3 to 1·10^–6 M by the use of³H- and¹⁴C-labels and product analysis by HPLC. Iodinations by chloramine-T/I^– gave (^k ₁ obs/^k ₂ obs)· values (=the pH dependent factor) in the range 72±3 to 55±2 and molecular iodine iodinations gave values in the range 64±5 to 39±10. It is concluded that molecular iodine is the iodinating species in both cases.     

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.     

Rapid determination of90Sr by Compton suppression gamma-ray spectrometry

This work presents a low-level background gamma spectrometry system capable of achieving rapid determination of⁹⁰Sr without chemical separation, in a soil sample when the⁹⁰Sr to -ray emitting nuclide concentration ratio exceeds 10. The system consists of a highly efficient HPGe central detector operated in coincidence or anticoincidence with a NaI(Tl) guard detector and a NaI(Tl) backscatter detector. Experimental results indicate that the bremstrahlung radiation from a pure -emitter can be distinguished with respect to the differences in normal and coincidence spectra. The⁹⁰Sr activity can be directly detemined in the sample in less than 1 hour with a minimum detectable concentration (MDC) estimated at 0.002 Bq·g^–1 for a sample containing no appreciable -ray nuclides or other high energy, -emitting nuclides. In actual measurement, a 0.06 Bq·g^–1 MDC for contaminated soils is achieved.     

Photoreduction of nitrobenzene to aniline in “hybrid” photocatalytic systems

Irradiation of suspensions of CdS in water-ethanol mixtures containing nibrobenzene with light at > 320 run does not in practical terms lead to the reduction of the nitrobenzene to aniline. It has been shown that the formation of aniline occurs when solvato complexes of vanadium(III) (PhNH₂=18.1·10^–3) and vanadium(IV) (PhNH₂= 2.84·10^–3) are added to the system. The photocatalytic reduction of nitrobenzene is accompanied by oxidation of the alcohol to acetaldehyde and acetal. The proposed process mechanism includes stages and acceptance of an electron photogenerated in the semiconductor by vanadium compounds and of a hole by molecules of the alcohol and subsequent stages of reaction of the reduced forms of vanadium, and also of the ethoxy radicals with nitrobenzene, which leads to its reduction.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 5, pp. 550–557, September–October, 1989.     

Kinetic Spectrophotometric Determination of Chromium (VI) by Oxidation of Sodium Pyrogallol-5-sulphonate by Hydrogen Peroxide

Summary. A new selective, sensitive, and simple kinetic method is developed for the determination of trace amounts of chromium (VI). The method is based on the catalytic effect of Cr(VI) on the reaction of sodium pyrogallol-5-sulphonate (PS) with hydrogen peroxide. The reaction is followed spectrophotometrically by tracing the oxidation product at 437nm within 1min after addition of H₂O₂. The optimum reaction conditions are PS (1.32·10^–3mol·dm^–3), H₂O₂ (0.32mol·dm^–3), HClO₄ (2.6·10^–3mol·dm^–3) at 25°C. Following this procedure, chromium (VI) can be determined with a linear calibration graph up to 0.25ng·cm^–3 and a detection limit of 0.024ng·cm^–3, based on the 3 criterion. The interference effect of several species was also investigated and it was found that the most common cations and anions do not interfere with the determination. The developed procedure was successfully applied to the determination of Cr(VI) and total Cr in river waters and total Cr in herbal samples.     

Development and Validation of Catalytic Kinetic Spectrophotometric Method for Determination of Copper(II)

A catalytic kinetic spectrophotometric method is developed for the determination of trace amounts of Cu(II). It is based on the catalytic effect of Cu(II) on the oxidation of cysteine (RSH) by hexacyanoferrate(III) in acidic medium. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of hexacyanoferrate(III) at 420nm. The optimum operating conditions regarding concentration of reagents, pH and temperature were established. The working curve is linear in the concentration range of 0–6.35ng·mL^–1. The maximum percentage error and standard deviation for determination of Cu(II) in the range of 1.27–6.35ng·mL^–1 have been calculated to be 3.9 and 0.4 respectively. The detection limit calculated was 0.15ng·mL^–1. The interference effect of several species was also investigated, and it was found that the most common cations and anions do not interfere with the determination. The developed procedure was successfully applied to the determination of Cu(II) in various synthetic and real samples. The typical feature of this procedure is that determination can be carried out at 25°C and/or in the absence of any precision thermostatic bath in the very short analysis time of one minute. The newly developed method was found to have fairly good selectivity, sensitivity, simplicity and rapidity compared to other kinetic methods.Received October 8, 2002; accepted April 7, 2003 Published online July 16, 2003     

Differential pulse-polarographic determination of adenine, adenosine and mono-, di- and tri-phosphate of adenosine

Summary The application of differential pulse polarography for the quantitative trace determination of adenine, adenosine, adenosine-3-monophosphate, adenosine-5-monophosphate, adenosine-5-diphosphate and adenosine-5-triphosphate has been investigated. Optimum conditions were found (pulse amplitude 100 mV, scan rate 2 mV · s^–1, drop time 2s). The effect of pH was studied, and the optimum pH was determined to give the highest sensitivity. The detection limit for adenine, adenosine and A-5-MP is ca. 2.2 ×10^–6M, 1.5×10^–6M and 2.99×10^–6M, respectively; for the other adenosine nucleotides it is 4.45×10^–6M. The validity of this method is supported by the constancy of the i _DPP/C values.

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Bestimmung von Adenin, Adenosin sowie Adenosinmono-, -di- und -triphosphat durch Differential-Puls-Polarographie

Zusammenfassung Die Anwendbarkeit der Differential-Puls-Polarographie zur quantitativen Spurenbestimmung von Adenin, Adenosin, Adenosin-3-monophosphat, Adenosin-5-monophosphat, Adenosin-5-diphosphat und Adenosin-5-triphosphat wurde geprüft und optimale Bedingungen ausgearbeitet (Pulsamplitude 100mV, Abtastgeschwindigkeit 2 mV/s, Tropfzeit 2s). Der Einfluß des pH-Wertes wurde untersucht und der optimale pH für maximale Empfindlichkeit bestimmt. Die Nachweisgrenzen für Adenin, Adenosin und A-5-MP betragen etwa 2,2 · 10^–6M, 1,5 · 10^–6M bzw. 2,99 · 10^–6M, für die übrigen Adenosinnucleotide 4,45 · 10^–6M. Die Brauchbarkeit der Methode ergibt sich aus der Konstanz der i _DPP/C-Werte.

     

Kinetic Spectrophotometric Determination of Chromium (VI) by Oxidation of Sodium Pyrogallol-5-sulphonate by Hydrogen Peroxide

A new selective, sensitive, and simple kinetic method is developed for the determination of trace amounts of chromium (VI). The method is based on the catalytic effect of Cr(VI) on the reaction of sodium pyrogallol-5-sulphonate (PS) with hydrogen peroxide. The reaction is followed spectrophotometrically by tracing the oxidation product at 437nm within 1min after addition of H₂O₂. The optimum reaction conditions are PS (1.32·10^–3mol·dm^–3), H₂O₂ (0.32mol·dm^–3), HClO₄ (2.6·10^–3mol·dm^–3) at 25°C. Following this procedure, chromium (VI) can be determined with a linear calibration graph up to 0.25ng·cm^–3 and a detection limit of 0.024ng·cm^–3, based on the 3 criterion. The interference effect of several species was also investigated and it was found that the most common cations and anions do not interfere with the determination. The developed procedure was successfully applied to the determination of Cr(VI) and total Cr in river waters and total Cr in herbal samples.     

A sensitive spectrophotometric determination of niobium(V) with the reagent 5-chloro-8-hydroxy-7-iodoquinoline

Summary The determination of niobium at levels of 0.02% and above is required in certain types of stainless steels and niobium stabilized steels. A method has been developed for the determination of microgram amounts of niobium in stainless steels with the reagent 5-chloro-8-hydroxy-7-iodoquinoline in citric acid medium. The effects of heating time, pH, reagent concentration and other variables have been studied. The system obeyes Beer's law over the concentration range investigated. The optimum concentration range for measurements in 10-mm cells is 1.0–10.0g of niobium ml^–1. The molar absorptivity of the complex is 5.143 x 10³l·moli–1·cm^–1. The interferences from foreign ions have been evaluated. The stoichiometry of the complex ML₂ (metal:ligand) was confirmed by Job's continuous variations and mole ratio methods.

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Empfindliche spektrophotometrische Bestimmung von Niob(V) mit S-Chlor-8-hydroxy-7-jodchinolin

Zusammenfassung Die Bestimmung von Niob in der Größenordnung von 0,02% und darüber ist in der Stahlanalyse nötig. Ein Verfahren zur Bestimmung von Mikrogrammengen Niob in rostfreien Stählen mit 5-Chlor-8-hydroxy-7-jodchinolin in zitronensaurem Medium wurde ausgearbeitet. Der Einfluß von Temperatur, Zeit, pH, Reagenskonzentration u. a. wurde untersucht. In dem angegebenen Bereich folgt die Reaktion dem Beerschen Gesetz. Bei Verwendung von 10-mm-Küvetten ist die Menge von 1,0–10,0g/ml optimal. Die molare Absorptivität des Komplexes beträgt 5,143 x 10,0³l·mol^–1·cm^–1. Fremdioneneinflüsse wurden untersucht. Die Stöchiometrie des Komplexes (Metall:Ligand=12) wurde bestätigt.

     

Measurement of30Si as a tracer by neutron-induced prompt gamma-ray analysis

The application of stable isotope analysis using neutron-induced prompt -ray analysis (PGA) with cold/thermal neutron beams for the tracer study of geological materials are discussed. Silicon has three natural isotopes differing in abundance:²⁸Si (92.23%),²⁹Si (4.67%) and³⁰Si (3.10%). For the purpose of the assessment of Si migration in engineered barrier material, enriched³⁰Si can be used as a tracer due to its nuclear and chemical properties. Isotope analysis of³⁰Si was performed by PGA during the tracer study. Neutron intensity at the sample position was 1.4·10⁸ n¢cm^–2·s^–1, 2.4·10⁷ n·cm^–2·s^–1 for cold and themal neutron guided beams of JRR-3M, respectively. Calibration curves and analytical sensitivity of³⁰Si were determined based on measurement of standard samples. BG and detection limits for³⁰Si analysis were also measured in Japanese bentonite (Kunigel V1 and Kunipia F) and their pore water. Fiffteen elements were determined simultaneously using PGA.     

Aktivierungsanalytische Spurenbestimmung von Magnesium und Mangan in biologischer Matrix

Zusammenfassung Die Bestimmung kleinster Magnesium und Manganmengen nebeneinander, wie sie häufig etwa in biologischem Material erforderlich ist, bereitet bislang Schwierigkeiten. Aktivierungsanalytische Untersuchungen durch Bestrahlung mit thermischen Neutronen haben sogar zu Verwechslungen Anlaß gegeben, die sich durch die kurze Halbwertzeit des²⁷Mg im Verein mit der geringen Differenz der-Energien von²⁷Mg (0,844 MeV) und⁵⁶Mn (0,877 MeV) erklären lassen.Durch Auftrennung eines im thermischen Neutronenfluß von 3,5·10¹³ respektive 7·10¹³ n·cm^–2·sek^–1 bestrahlten Mg-Mn-Salzgemisches an einem Chelex-100-Ionenaustauscher und Elution mit Acetatpuffer p_H=6,25 konnte eine einwandfreie Trennung beider Nuklide bei einer vernachlässigbaren, respektive ohne Verunreinigung des eluierten Mg durch Mn erzielt werden. Die Anwendung des Verfahrens bei der Bestimmung des Mg- und Mn-Gehaltes von Reis wird beschrieben.

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Determination of traces of magnesium and manganese in biological material by activation analysis

Summary The determination of trace amounts of magnesium in the presence of manganese in biological matrixes rendered great difficulties in the past. Activation analysis with thermal neutrons could lead to errors because of the short half-time of²⁷Mg and similarities in-energy of²⁷Mg and⁵⁶Mn (0,844 MeV and 0,847 MeV, respectively). In the present work the ionexchange chromatography using Chelex-100 resin and elution with the acetate buffer (p_H 6,25) has been employed for the separation of the mixture of Mg and Mn salts, irradiated with thermal neutron flux of 3.5 · 10¹³ n · cm^–2 · · sec^–1 or 7·10¹³ n·cm^–2·sec^–1. The results show that both elements can be obtained in the pure form, or with a very small degree of contamination of magnesium with manganese. Application of the method for the determination of the Mg- and Mn-content in rice is described.

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Auszugsweise vorgetragen auf dem VI. Intern. Symposium für Mikrochemie, G-raz, September 1970.     

Influence of added water on pathways and efficiency of photocatalytic reactions in ethanol solutions of titanium tetrachloride

Electronic spectroscopy, ESR, and gas-liquid chromatography have been used in studying the action of light with =254 nm on ethanol-water solutions of titanium tetrachloride. It has been established that, in the course of irradiation, a photocatalytic process develops with the participation of coordination compounds of titanium(IV) and (III), resulting in oxidation and breakdown of the ethanol to form acetaldehyde, methane, ethane, ethyl chloride, and molecular hydrogen. In the presence of small amounts of added water (up to 0.5 M), the efficiency of CH₄ and C₂H₇ formation is much lower but the yield of H₂ is higher, in comparison with the yields of these products in absolute ethanol. With further increases in the water concentration, the rates of formation of methane, ethane, and acetaldehyde increase. The maximum quantum yields () are as follows: (CH₄)=1.8 · 10^–4 and (C₂H₆)=1 · 10^–3 in absolute ethanol; (CH₃CHO)= 1.6·10^–2 in ethanol with the addition of 6.0 M H₂O; (H₂)=6.7·10^–3 in solutions containing 0.5 M H₂O. The observed differences in the product yields are explained by a change in the composition and structure of the titanium compounds that act as the photocatalyst, a change that takes place when the water concentration is varied. A mechanism is proposed for these reactions.Translated from Teoreticheskaya i Éksperimentai'naya Khimiya, Vol. 22, No. 1, pp. 51–58, January–February, 1986.     

Microdetermination of bromate ions with antipyrine

Summary A spectrophotometric method for the micro-determination of bromate ions has been described. A red colored complex is obtained when 3 ml of 5% antipyrine, 3 ml of 60% perchloric acid and 1 ml of 0.1M sodium nitrite solution are added in a solution containing bromate ions. The maximum absorbance occurs at 525 nm. Beer's law is obeyed for solutions containing 25.0–140.0/ml of bromate ions. Sensitivity has been found to be 0.029g BrO₃ ^–/cm² for logI ₀/I=0.04 with a molar absorptivity of 2·10³ moles^–1, cm^–1. liter. As(III), Ce(IV), Fe(III), CrO₄ ^2–, Cr₂O₇ ^2–, and Cl^– interfere in the determination.

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Zusammenfassung Eine spektrophotometrische Methode zur Mikrobestimmung von Bromationen wurde beschrieben. Nach dem Zusatz von 3 ml 5%iger Antipyrinlösung, 3 ml 60% iger Perchlorsäure und lml 0,1 ·m Natriumnitrit zu einer bromathaltigen Lösung erhält man eine rot gefärbte Komplexverbindung. Deren Absorptionsmaximum liegt bei 525 nm. Lösungen mit 25,0 bis 140,0g Bromat/ml entsprechen dem Beerschen Gesetz. Die Empfindlichkeit der Reaktion beträgt 0,029g BrO₃ ^–/cm₂ für logI ₀/I=0,04 mit einer molaren Absorption von 2 · 10³ m^–1 · cm^–1 · 1. As(III), Ce(IV), Fe(III), CrO₄ ^2–, Cr²O₇ ^2– und Cl^– stören die Bestimmung.