Radiochemical determination of Caesium-137, strontium-89,90 and barium-140 in milk and bone ash

Summary A method for the determination of radiocaesium, radiostrontium, radiobarium in milk and bone ash is described. An alkaline fusion of ash followed by leaching with water provides for the preliminary separation of radiocaesium. After dissolution of leaching residue in hydrochloric acid and sorption on Dowex 50 W, X-8, radioyttrium (rare earths fission products), magnesium and calcium are eluted with 1.0 M ammonium lactate, pH 7.5. Radiostrontium, radiobarium and radium are separated by elution with 0.15 M ammonium citrate, pH 7.5. ¹³⁷Cs is isolated as Cs-dipicrylaminate, ⁸⁹Sr/⁹⁰Sr as SrCO₃, ¹⁴⁰Ba as BaCO₃ and counted on a low-background beta-counter. For determined radionuclides the average chemical yields amount to 80%. The limits of detection for ¹³⁷Cs, ⁹⁰Sr, ¹⁴⁰Ba are 0.02 pCi/g with a 10 g sample of milk ash and 0.04 pCi/g with a 4 g sample of bone ash, respectively.

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Radiochemische Bestimmung von Caesium-137, Strontium-89,90 und Barium-140 in Milch- und Knochenasche

Zusammenfassung Zur Vorabtrennung von Radio-Caesium wird die Ascheprobe alkalisch geschmolzen und dann mit Wasser ausgelaugt. Nach Auflösung des ausgelaugten Rückstandes in Salzsäure und Sorption an Dowex 50 W, X-8 werden Yttrium (Spaltprodukte der Seltenen Erden), Magnesium und Calcium mit 1,0 M Ammoniumlactat, pH 7,5 eluiert. Radio-Strontium, Radio-Barium und Radium werden durch Elution mit 0,15 M Ammoniumcitrat, pH 7,5, abgetrennt. ¹³⁷Cs wird als Cs-Dipikrylaminat isoliert, ⁸⁹Sr/⁹⁰Sr als SrCO₃,¹⁴⁰Ba als BaCO₃; gemessen wird in einem Beta-Antikoincidenzzähler. Für die bestimmten Radio-Nuklide beträgt die durchschnittliche Rückgewinnung 80%. Die unteren Nachweisgrenzen für ¹³⁷Cs, ⁹⁰Sr, ¹⁴⁰Ba betragen bei einer 10 g-Milchasche-Probe 0,02 pCi/g und bei einer 4 g-Knochenasche-Probe 0,04 pCi/g.

     

A rapid solvent extraction method for the determination of caesium-137 in environmental materials

A solvent extraction method for the quantitative determination of caesium-137 in environmental samples is described. Caesium carrier is added to the ashed sample, which is dissolved with hydrochloric acid. The solution is filtered to remove any carbon and the pH is adjusted to 2.0. Sodium dodecylbenzene sulphonate is added and the extraction is done with phenol-nitrobenzene mixture. The organic phase is washed with EDTA solution and the caesium is stripped from the washed solvent with 6 M hydrochloric acid. The caesium is precipitated as caesium chlorostannate to ensure absolute decontamination from potassium-40. Recovery from standard solution is about 85% and from vegetation, rainwater and effluent samples about 80%. The method is applicable in the presence of large quantities of interfering ions, and decontamination factors for many nuclides are greater than 10³.     

Determination of caesium-137 in fast-reactor coolant systems

A method for the separation of caesium by ion-exchange involving ammonium 12-molybdophosphate has been investigated, and found to be 100% efficient for aqueous solutions with high sodium and potassium concentrations.     

Radiochemical procedure for the determination of plutonium isotopes in powdered milk

Summary A radiochemical procedure for the determination of alpha-emitting isotopes of plutonium in powdered milk is proposed. The procedure involves sample dissolution (by HNO₃ and HClO₄), separation by ionic-exchange resin, electrodeposition and alpha-spectroscopy. In order to determine the chemical recovery, ²⁴²Pu was employed as a tracer. A reference material (Marine Sediment IAEA 135) was analyzed to validate such procedure, and to show its reliability. Afterwards, some powdered milk, produced for international trade, was analyzed and chemical recovery was found to be around 95%.     

Radioanalytical determination of137Cs and89Sr in milk

Separation of Cs, Sr and Ca from their mixture was studied using solvent extraction and ion exchange techniques. More than 90% separation efficiency was achieved for Ca–Sr separation using ion exchange resin (Doulite C-20) while solvent extraction amounted to 88%. A proposed technique for determination of¹³⁷Cs and⁸⁹Sr in milk (after removal of organic matter) showed more than 80% accuracy for⁸⁹Sr determination and more than 90% for¹³⁷Cs determination.     

Silica gel as a support for inorganic ion- exchangers for the determination of caesium-137 in natural waters

The preparation and characteristics of ammonium molybdophosphate and potassium or ammonium hexacyanocobalt ferrate supported in silica gel, and their application to the determination of (137)Cs in natural waters are described. Use of columns of these materials gives better recovery of (137)Cs from natural waters (in comparison with co-precipitation with ammonium molybdophosphate), requires less exchanger, so raising the gamma-counting efficiency of (137)Cs, and permits elimination of other radionuclides by washing with hydrofluoric acid.     

Determination of caesium-137 in water samples using modified carbon microfibers

In this paper, the possibility of caesium sorption on microfibres produced by the Slovak Academy of Sciences was investigated. Sorption capacity limit of sorbent was increased by chemical modification. The binding of Cs to the surface of potassium copper ferrocyanide modified carbon microfibers was demonstrated by SEM–EDX analysis. Statistical comparison of the models showed that the Freundlich isothermal model was more suitable for describing sorption processes. The influence of desorption, pH value, competing ions and water volume were also tested. According to the results, this method seems to be suitable for large-scale caesium separation from contaminated waters.

     

Radiochemical determination of antimony

A radioanalytical method based on substoichiometric principles has been developed for the extraction and determination of antimony/III/ with 1-/2-pyridylazo/-2-naphthol /PAN/. Antimony/III/ forms a red complex with PAN in the presence of I^– or Br^–, which is extractable into benzene from sulphuric acid media.     

Effects of topography on caesium-137 in montane peat soils and vegetation.

This study investigated the relationship between altitude and 137Cs fallout in soils and plants. The soils and plants, Calluna vulgaris, Erica cinerea and Molinia caerulea, were sampled across a transect of two valleys in north-western Ireland. The results provided evidence that greater 137Cs deposition to soils occurred at higher altitudes, and the data supported the findings of a previous investigation in the same area. A valley effect, whereby greater concentrations of 137Cs accumulated in plants on the lower altitudes of the valley floors, was shown to be significant. Deposition values for total 137Cs in soils were not correlated with plant concentrations, although a relationship between concentrations in C. vulgaris and M. caerulea was found to be statistically significant. No relationship was observed between the 137Cs from weapons fallout with that of Chernobyl origin in the 0-10 cm depth soils, although a significant correlation emerged between the same two components measured in C. vulgaris. The results suggest that existing definitions of concentration ratios and transfer factors are, for many reasons, inappropriate for studies of soil to plant transfer of 137Cs in peatland ecosystems.     

Radiochemical determination of uranium and radium isotope in natural water using liquid scintillation counter

²³⁴U, ²³⁸U, ²²⁶Ra, and ²²⁸Ra were analyzed in 14 Korean hot spring waters. Uranium was extracted with mixture of extractive scintillation cocktail containing HDEHP and ²³⁴U, ²³⁸U were analyzed with LSC. Radium isotopes were separated using Ba coprecipitation method and counted with LSC and ²²⁸Ra was also analyzed its daughter ²²⁸Ac with HPGe γ-detector. Among them ²²⁶Ra was ranged <0.01–0.155 Bq/L and ²²⁸Ra is below detection limit <0.1 Bq/L. And also, uranium content was ranged <0.01–49.7 μg/L and ²³⁴U/²³⁸U ratio was ranged 0.69–1.17.     

Radiochemical determination of technetium-99

The radiochemistry of technetium-99 is reviewed and the different measurement techniques are compared. Experimental results on sorption of technetium on two different types of ion exchange resins using^99mTc and^95mTc as chemical yield tracers are presented. Spectra calibrations of liquid scintillation counter using^95mTc as chemical yield tracer of⁹⁹Tc are discussed.     

Rapid liquid chromatographic determination of oxytetracycline in milk.

A simple method for the determination of residual oxytetracycline (OTC) in milk by high-performance liquid chromatography (HPLC) was developed. The sample preparation could be made without complex extraction and clean-up procedures. A LiChrospher 100 RP-8 end-capped column and a mobile phase of acetonitrile-acetic acid-water (28:4:68, v/v/v) with a photo-diode array detector was used. The average recoveries from spiked OTC (0.1, 0.5 and 1.0 microgram/ml) were in excess of 89.8% with coefficients of variation between 0.6 and 4.1%. The limit of detection was 0.05 microgram/ml. The total time required for the analysis of one sample was below 10 min.     

Radiochemical determination of ruthenium-106 in urine

The method is based on volatilization of Ru in the form of RuO₄ by distillation of wetashed urine with KMnO₄, precipitation of Ru hydroxide, and β-counting. Before the distillation, most of the organic compounds are destroyed by wet-ashing with H₂SO₄ and 30% H₂O₂ at 140°C, with subsequent evaporation until fuming. The chemical recovery is determined photometrically at 430 nm using the solution of β-counted Ru hydroxide in KIO₄/KOH reagent. The mean recovery is about 70%.     

Radiochemical determination of low unsaturations in polyisobutene

A radiochemical technique involving the use of ³⁶Cl has been described previously for the measurement of butyl rubber unsaturations. This method has now been applied to the estimation of the much lower concentration of double bonds present in polyisobutene prepared by the cationic polymerization of isobutene at a low temperature. The nature of the reaction of polyisobutene with radiochlorine in the absence of air is examined, and the experimental results are discussed in relation to present theories of the mechanisms of chain termination in cationic polymerization.     

Determination of caesium-137 soil-to-plant concentration ratios for vegetables in Goiania City,Brazil

The radiological accident that occurred in Goiania City, Brazil, in September 1987, led to the spreading of¹³⁷Cs in the urban area. Even after the decontamination procedure, there was a reminiscence of¹³⁷Cs activity in the soil of residential gardens. This activity was enough to conduct preliminary experiments for determination of soil to vegetable concentration ratios. Experiments were conducted for carrots, lettuce and radishes. Two types of experimental patterns were used to determine the concentration ratios: lysimeters cultivation under greenhouse condition and soil cultivation in open field plot. The concentration ratios measured for cultivation under greenhouse and field plot conditions are considerably higher than those mentioned in the International Union of Radioecologist (IUR) data bank for the same vegetables and cultivation condition.     

Radiochemical determination of oxygen traces in selenium

A sensitive method for determination of oxygen in selenium is described. Oxygen is converted into the gaseous compound sulfur dioxide labelled with³⁵S. The β-radiation of³⁵S is measured by liquid scintillation counting. The detection limit is 0.02 ppm. The efficiency of vacuum distillation in the purification of selenium, and the influence of air, dry oxygen and water on the absorption of oxygen by selenium have been investigated.     

Radiochemical determination of Mo in pure tungsten

A radiochemical neutron activation technique for Mo determination in high purity tungsten, based on some specific properties of Mo and W radionuclides has been developed. Al₂O₃ powder has been used as a sorbent. An estimation of the Mo content was carried out via the selectively separated^99mTc daughter radionuclide. Limit of detection was 10 ng g^–1.     

Rapid liquid chromatographic determination of residual penicillin G in milk

A simple and rapid high-performance liquid chromatographic (HPLC) method for determination of residual penicillin G (benzylpenicillin, PCG) in milk was developed. The sample preparation was performed by stirring with ethanol and reacting with 5 M 1,2,4-triazole-mercury (II) chloride solution at 65?°C for 10 min followed by an ultra centrifugation step. The HPLC separation was carried out using a Mightysil^® RP-4GP column, a mobile phase of acetonitrile and 0.1 M phosphate buffer (pH 6.5) (35:65, v/v) and a photo-diode array detector. The average recoveries from spiked PCG (0.004, 0.01, 0.05 and 0.1 μg/mL) were above 86% with coefficients of variation between 1.2 and 4.5%. The limit of detection was 0.004 μg/mL. This value corresponds to the maximum residue limit (MRL) in milk (0.004 μg/mL, EU and Japan). The total time required for the analysis of one sample was below 40 min.     

Rapid liquid chromatographic determination of residual penicillin G in milk

A simple and rapid high-performance liquid chromatographic (HPLC) method for determination of residual penicillin G (benzylpenicillin, PCG) in milk was developed. The sample preparation was performed by stirring with ethanol and reacting with 5 M 1,2,4-triazole-mercury (II) chloride solution at 65 degrees C for 10 min followed by an ultra centrifugation step. The HPLC separation was carried out using a Mightysil RP-4GP column, a mobile phase of acetonitrile and 0.1 M phosphate buffer (pH 6.5) (35:65, v/v) and a photo-diode array detector. The average recoveries from spiked PCG (0.004, 0.01, 0.05 and 0.1 microgram/mL) were above 86% with coefficients of variation between 1.2 and 4.5%. The limit of detection was 0.004 microgram/mL. This value corresponds to the maximum residue limit (MRL) in milk (0.004 microgram/mL, EU and Japan). The total time required for the analysis of one sample was below 40 min.