Measurement of radioactive samples in Marinelli beakers by gamma-ray spectrometry

Radioactivity measurement of environmental samples is frequently assayed by gamma-ray spectrometry using Marinelli beakers. In this work, self-absorption and coincidence summing effects arising in activity measurements for Marinelli beaker geometry have been studied with a Ge detector. Three types of Marinelli beakers which have capacities of 450 mL, 1 L, and 2 L were developed. Self-attenuation effects for density variation of radioactive samples in each type of the Marinelli beakers were measured as a function of gamma-ray energy, and also the results were compared with calculated values by mathematical model. Meanwhile, the coincidence summing effects of¹²⁵Sb and¹⁵⁴Eu nuclides were obtained from the determination of the full-energy peak and total efficiencies for a Ge detector.     

Measurement of63Ni in highly radioactive Hanford waste by liquid scintillation counting

Characterization of high-activity radioactive waste stored in underground tanks at Hanford requires determining⁶³Ni (100 y). This low-energy -emitter (E_max 67 keV) must be separated with a high degree of radiochemical purity large amounts of other fission and activation products. The method to be discussed involves multiple precipitation steps with several holdback carriers added, followed by precipitations with dimethylglyoxime, ion exchange, and electrodeposition. The⁵⁹Ni activity is determined by low-energy photon spectrometry. The sample is then stripped from the counting disk with HNO₃, converted to the chloride form, and the⁶³Ni -spectrum is measured with high efficiency by liquid scintillation counting.Pacific Northwest Laboratory is operated for the U.S. Department of Energy under Contract DE-AC06-76RLO-1830.     

Measurement of filtering efficiency of artificial radioactive aerosol filter membrane

Journal of Radioanalytical and Nuclear Chemistry - When monitoring radioactive aerosol in the atmosphere, choosing a filter membrane with better surface collection characteristics and filtering...     

Preparation of radioactive chloramine-B by isotopic exchange with radioactive chlorine

The exchange between chloramine-B and radioactive chlorine has been carried out in various media. The exchange is slow in strong acid and very weak acid media. Its maximum is at pH 3.3. There is no exchange in alkaline media. Optimum conditions for the preparation of radiochloramine-B with high specific activity are reported.     

Preparation of radioactive bromamine-T by isotope exchange with radioactive bromine

In hearts of mice the accumulation of 15-/para-¹²³I-phenyl/-pentadecanoic acid /IPPA/ was determined 3 min after injection under different conditions. Using propionate as an agent competing with the albumin binding sites for fatty acids, the concentration of free fatty acids was increased in the circulating blood and the myocardial uptake of IPPA rose from 38.8±3.7% inj. dose/g under normal conditions to 46.2±5.1% inj. dose/g. On the other hand, the addition of 2-Br-palmitic acid reduced the myocardial uptake to a value of 31.0±2.5 inj. dose/g due to the known effect of blocking the transport of fatty acids into the cells. The results suggest the existence of a carrier-mediated transport process of fatty acids into the myocardial tissue.     

Determination of glycerophosphate and other anions in dentifrices by ion chromatography

Simple, reliable and sensitive analytical methods to determine the anions, such as fluoride, monofluorophaosphate, glycerophosphate related to anticaries are necessary for basic investigations of anticaries and quality control of dentifrices. A method for the simultaneous determination of organic acids, organic anions and inorganic anions in the sample of commercial toothpaste is proposed. Nine anions (fluoride, chloride, nitrite, nitrate, sulfate, phosphate, monofluorophaosphate, glycerophosphate and oxalic acid) were analyzed by means of ion chromatography using a gradient elution with KOH as mobile phase, IonPac AS18 as the separation column and suppressed conductivity detection. Optimized analytical conditions were further validated in terms of accuracy, precision and total uncertainty and the results showed the reliability of the IC method. The relative standard deviations (RSD) of the retention time and peak area of all species were less than 0.170 and 1.800%, respectively. The correlation coefficients for target analytes ranged from 0.9985 to 0.9996. The detection limit (signal to noise ratio of 3:1) of this method was at low ppb level (<15 ppb). The spiked recoveries for the anions were 96-103%. The method was applied to toothpaste without interferences.     

Analysis of parabens in dentifrices and the oral cavity

This study analyzed levels of parabens in commercial dentifrices and saliva. HPLC was performed using 35% acetonitrile and measuring absorbance at 254 nm. Thirteen toothpastes and five mouthwashes were analyzed. Of these, volunteers used three toothpastes and two mouthwashes, and levels of parabens were analyzed in saliva and water used for mouth rinsing. In toothpastes, the highest concentrations of methylparaben (MP), propylparaben (PP) and n‐butylparaben (nBP) were 1.86, 1.42 and 1.87 mg/g, respectively. In mouthwashes, the highest concentrations of MP and PP were 0.97 and 0.11 mg/mL, respectively. After volunteers used 500 mg toothpaste T‐1, which contained 895 µg MP, the first and tenth mouth rinse samples contained means of 64.63 and 1.89 µg MP, respectively. After rinsing the mouth three or five times, 37 µg or 18 µg MP was calculated to remain in the oral cavity, respectively. After using 20 mL mouthwash S‐1, which contained 19 mg MP, 1.53 mg MP was calculated to remain in the oral cavity. Immediately after using this mouthwash, the mean salivary concentration of MP was 237 µg/mL. The daily intake of parabens from dentifrices was predicted to be insignificant compared with the intake from food; however, parabens can be ingested from dentifrices. Copyright © 2014 John Wiley & Sons, Ltd.     

Concentration of radioactive components in liquid low-level radioactive waste by membrane distillation

The paper addresses some aspects of liquid low-level radioactive waste (LLLW) purification. Since the volume of liquid low-level wastes is usually large and the activity is rather low, the radioactive substances separated from the non-active portion have to be concentrated into the small volume for subsequent conditioning and disposal. The need for the improvement of decontamination and minimisation of the costs have led to new specific methods being under examination and development. The method proposed in the paper is membrane distillation. The experimental work described below supports the statement that membrane distillation can be an attractive alternative for liquid radioactive waste treatment. The advantages of membrane distillation over the other processes commonly used for the processing of LLLW are discussed in the paper.     

Measurement of uranium in human teeth and kidney stones with the fission track technique

The measurement of uranium in human teeth and kidney stones has been carried out by using the fission track activation technique. In this determination 2759 and 2205 absolute counts of tracks /for standard: 6940 and 1556/ for teeth samples and 1689 tracks /for standard: 1446/ for kidney stone samples have been made, respectively. The results obtained by this technique are the following: X_tooth/1/=/0.227±0.006/ ppm, X_tooth/2/=/0.143±0.007/ ppm and X_kidney=/0.568±0.020/ ppm. The experimental method is described and the results discussed.     

Biosorption of radioactive thorium by Sargassum filipendula

In the present work, the biosorption of radioactive thorium was investigated using a dry biomass of Sargassum filipendula as the biosorbent material. Radioactive solutions containing between 2.0 and 500.0μg thorium were tested by biosorption with S. filipendula, yielding uptake capacities from 20 to 100%, depending on the concentration of the solution. Kinetic studies indicated that equilibrium between the thorium solution and the solid fraction was achieved after three hours of contact and that a second-order model could express the equilibrium kinetics. In order to investigate the maximum biosorption capacity of the biomass an isotherm was done, based on the experimental data, which revealed the maximum uptake capacity to be 2.59 μmol thorium/g biomass. The experimental data fitted well to a Langmuir model, which provided a good correlation between the experimental and predicted thorium uptake values.     

Adsorption of radioactive iodide by natural zeolites

The vacancy transfer probabilities of K to L₁, L₂ and L₃ shell were measured with a new method. The L X-ray yields of targets excited by 59.5 keV incident photons, i.e., above the K edge of elements, were detected with a high-resolution Si(Li) detector. For comparison with the experimental results, theoretical calculations were made using data available on radiative and radiationless transitions. The radiative transition values of these elements were taken from the relativistic Hartree-Slater model, those of the radiationless transitions from the Dirac-Hartree-Slater model. The measured values were found to be in good agreement with theoretical ones. The h_KLi (i = 1, 2, 3) values were calculated by measuring the L_1x, L_2x and L_3x X-ray production cross-sections.     

Measurement of formaldehyde as dimedone adduct and potential formaldehyde precursors in hard tissues of human teeth by overpressured layer chromatography

Simple, automatic overpressured layer chromatographic methods for the parallel determination of endogenous formaldehyde in the form of dimedone adduct and potential formaldehyde generators (betaines) in hard tissues of human teeth are described together with an efficient densitometric evaluation. These simple procedures involve the special preparation of teeth and extraction of formaldehyde, of different binding force in teeth, with methanol containing dimedone, and the isolation of betaines with an aqueous solution of methanol.     

Simultaneous determination of potassium nitrate and sodium monofluorophosphate in dentifrices by single column ion chromatography

The simultaneous determination of potassium nitrate and sodium monofluorophosphate in dentifrices by single column ion chromatography is described. Nitrate and monofluorophosphate are extracted from the dentifrice with deionized water and separated by a low capacity anion separator column with 0.2% sodium benzoate (adjusted to pH 5.8 +/- 0.1 with formic acid) as the mobile phase. A conductivity meter is used for concentration measurements. The method has been applied to commercial dentifrices containing both potassium nitrate and sodium monofluorophosphate. The mean recoveries for potassium nitrate and monofluorophosphate from spiked samples were 99.0% and 99.2%, respectively, with corresponding standard deviations of 1.73% and 2.55%. The minimum detectable concentration is 5 micrograms/ml for both nitrate and monofluorophosphate.     

Determination of ion adsorption by radioactive tracer technique

Summary The slight linear decrease of the “per mole of AgI adsorbed amount” (ˉC) of the coagulating ion with the increasing pI at a constant concentration of the coagulating ion was proved and explained by the linear decrease of the specific surface. The adsorbed amount of the coagulating ions at a constant concentration and at a given pI decreases with the increasing concentration in which the AgI precipitate was formed. Ions of different valencies are adsorbed in equivalent amounts which are independent of their concentrations which were higher than their coagulation values. The correctness of the desorption-adsorption formula logc″/c′=(z′−z″ a+ logx/(−x) respectivelyS=c″ (1−x)/c′x= 10(z′−z″)a was confirmed (x the fraction of the adsorbed amount of the ion of valencyz″ and concentrationc″, 1−x the fraction of the adsorbed amount of the ion of valencyz′ and concentration c′,S the selectivity coefficient of ion exchangers). Therefore the coagulated AgI can be considered as an ideal ion exchanger. The constanta in the above formula is equal to the slope of the line “log coagulation value-valency” of theSchulze-Hardy rule.

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Zusammenfassung Die leicht lineare Abnahme des pro Mol AgJ adsorbierten Betrages (ˉC) der koagulierenden Ionen mit steigendem p^J bei konstanter Konzentration des koagulierenden Ions wurde gezeigt und durch die lineare Abnahme der spez. Oberfl?che erkl?rt. Der adsorbierte Betrag an koagulierenden Ionen bei konstanter Konzentration und gegebenem p^J sinkt mit steigender Konzentration, mit der die AgJ-F?llung erzeugt wird. Ionen verschiedener Wertigkeiten werden in ?quivalenten Betr?gen unabh?ngig von ihren Konzentrationen adsorbiert und sind h?her als ihre Koagulationswerte. Die Richtigkeit der Desorption-Adsorptions-Formel logc″/c′=(z′−z″ a+logx/(−x) bzw.S=c″ (1−x)/c′x= 10(z′−z″)a wurde sichergestellt (x= Bruchteil des adsorbierten Betrages des Ions der Valenzz″ und dessen Konzentrationc″, 1 −x=Bruchteil des adsorbierten Betrages des Ions der Valenzz′ und der Konzentration c′,S=Selektivit?tskoeffizient des Ionenaustauschers). Deshalb kann das koagulierte AgJ als ein idealer Ionenaustauscher betrachtet werden. Die Konstantea in der obigen Formel ist gleich der Neigung der Kurve “log Koagulationswert/Valenz” in derSchulze-Hardy-Regel (2).

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Contribution number 95 from the Department of Physical Chemistry, Faculty of Sciences, University of Zagreb. Partially reported at the I. Yugoslav Congress for Pure and Applied Chemistry, Zagreb, June 1960.