Rapid determination of tritium and carbon-14 in urine samples using a combustion technique

Traditionally in bioassay monitoring, ³H determinations in urine have been performed using either direct counting (with or without sample decolourisation) or distillation whilst ¹⁴C has been determined on separate sub-samples following chemical isolation of the carbon from samples. Although these techniques are relatively straightforward they do not permit simultaneous determination of ³H/¹⁴C. For ³H, direct counting can be significantly affected by variations in sample composition/colour resulting in varying degrees of sample quench, does not distinguish between aqueous/organically-bound ³H and is limited to small sample sizes. This study describes the use of purpose built multi-tube combustion furnace for the simultaneous extraction and determination of ³H and ¹⁴C. The technique is insensitive to sample composition and can be adapted to measure Tritiated water (HTO) and organically bound tritium separately. The development of a multi-tube system with integrated cool-down facility permits rapid throughput of high sample numbers and has been proven effective in decommissioning waste characterisation. In addition, the furnace-based technique is capable of processing larger sample sizes, increasing analytical sensitivity and accuracy of dose assessment.     

Simultaneous determination of nitrogen and lithium by thermal neutron activation analysis

The determination of lithium and nitrogen in a variety of materials by thermal neutron activation is described. The nuclear reactions used are ¹⁴N(n,p)¹⁴C and ⁶ Li(n,α)³H. Radionuclides. ¹⁴C and ³H for counting are isolated by fusion of the irradiated sample in a vacuum system. Data are presented on lithium and nitrogen concentrations in several terrestrial standards. The new method allows reliable measurements on 10–50-mg samples.     

Simple measurement of14C in the environment using a gel suspension method

A simple analytical method for environmental¹⁴C with a low background liquid scintillation counter was developed. We used a new gelling agent, N-lauroyl-L-glutamic-α,γ-dibutylamide, for the liquid scintillation counting of¹⁴C as CaCO₃ (gel suspension method). Our procedure for sample preparation was much simpler than that of conventional methods and required no special equipment. The samples prepared with the standard sample of CaCO₃ were measured to evaluate the self absorption of the sample, the optimum condition of counting and the detection limit. Our results indicated that the newly developed technique could be efficiently applied for the monitoring of environmental¹⁴C.     

Critical assessment of vibrational and NMR spectroscopic techniques for the microstructure determination of polybutadienes

A critical assessment of infrared, Raman, and NMR (¹H and ¹³C) spectroscopic techniques for the microstructure determination of polybutadienes and partially hydrogenated polybutadienes is presented. The polybutadienes analysed in this work were produced by anionic polymerisation methods. Measurements have been made on the polymers in the solid state and in solution as appropriate and three different analytical methods have been used to obtain the infrared data. The Raman and ¹³C NMR spectroscopic methods of analysis were found to agree quite closely with each other but it is considered that the infrared analyses give poor characterisation of the microstructure whatever the experimental procedure used. Raman spectroscopy is the recommended technique for the analysis of polybutadiene microstructures in the solid state or in solution because of its speed, accuracy and reproducibility.     

Radiological inventory of irradiated graphite samples

In France, graphite is present as reflector, moderator or structural element in 9 gas cooled reactors which are now in the decommissioning phase The storage, whose characteristics have to be determined, dedicated to irradiated graphite is planned in France for 2010. Consequently, the radiological inventory of the graphite has to be done Measurement campaigns already organized on different graphite samples showed discrepancies for the computed “calculation/measurement” ratio and the necessity to acquire more experimental results was stressed. The ability to realize an experimental radiological inventory, with particular attention to ³H, ¹⁴C, ³⁶Cl, and ⁶³Ni, was studied. A new mineralization was developed based on an acid attack (iodic + sulfuric acid). This process causes a high gaseous emission and cannot be applied to analyses of volatile elements such as ¹⁴C, ³H, and ³⁶Cl. The routine pyrolysis protocol used to measure these elements in other matrices was specially adapted to the graphite samples. After these mineralizations, radiochemical steps were conducted in order to separate the different requested radionuclides. The mean yield of the complete separation process was evaluated for each of them and the detection limits were determined.     

A method for the determination of additive elements in sintered tungsten metal rods by fast neutron activation analysis

A non-destructive activation analytical method developed for the determination of the axial concentration distributions of Al, Si and K residual additives in sintered tungsten rods is briefly described. A 14 MeV neutron generator is used to produce the reactions²⁷Al(n, p)²⁷Mg,²⁸Si(n, p)²⁸Al and³⁹K(n, 2n)³⁸K and the activities are compared with standards. A weighted least-squares fitting program is used for peak area determination of the scintillation spectra. A scheme of the irradiating and measuring arrangement with a pneumatic sample-transfer system is presented. The system is applicable to large-scale routine analysis and lends itself well to automation. The results of preliminary measurements with this arrangement are given.     

Distribution of 14C and 3H in low level radioactive wastes generated by wet waste streams from pressurized water reactors

Summary It is impossible to detect ¹⁴C and ³H by direct methods such as γ-spectroscopy because they are pure b-emitters and thus they are classified as hard to measure nuclides (HTM). In this paper the analysis results of ¹⁴C and ³H in the low level radioactive wastes (LLWs), including spent ion exchange resin, evaporated bottom and sludge are presented. The LLWs were generated by three nuclear power plants (NPPs), in Korea all with pressurized water type reactors (PWRs). A simultaneous separation procedure for ¹⁴C and ³H in LLWs was established by wet oxidation-acid stripping. A liquid scintillation analyzer was used for the measurement of ¹⁴C and ³H. It was found that the recovery of ¹⁴C and ³H was 82-99 and 78-103%, respectively, by wet oxidation-acid stripping with diluted standard solutions. At the lowest injection of ¹⁴C and ³H, i.e., at 1.44 Bq for ¹⁴C and 1.22 Bq for ³H, the minimum detectable activity (MDA) of ¹⁴C and ³H was calculated as 0.88 and 0.78 Bq/g, respectively, for the minimum allowable sample weight, using wet oxidation and 16 wt% H₂SO₄ acid. By the wet oxidation-16 wt% H₂SO₄ stripping method no interfering nuclides were detected in the trapping solution of ¹⁴CO₂ and the distillate of ³H. The activity concentration range of ¹⁴C in the analyzed samples, i.e., spent ion exchange resin, evaporated bottom and sludge, was 0.17-110,000, 8.4-1380 and 0.1-10,006 Bq/g, respectively, and that of ³H in the same was from no detectable to 769, 134-14,383 and 0.7-4820 Bq/g, respectively.     

Spectrophotometric determination of linezolid in pharmaceuticals on the basis of coupled redox-complexation reactions

The present study describes three simple and sensitive spectrophotometric methods developed for the determination of linezolid (LZD) in pure and tablet forms. These methods are based on the oxidation of LZD by ferric chloride in the presence of 1,10-phenanthroline (method A), or 2,2′-bipyridyl (method B), or potassium ferricyanide (method C). The colored complexes were measured at 510, 522 and 758 nm for methods A, B and C, respectively. In all the methods, the absorbance is found to increase linearly with increasing LZD concentration. Beer’s law is obeyed over the concentration ranges of 0.5–6.0, 0.5–9.0 and 1.0–9.0 μg/mL for methods A, B and C, respectively. The calculated molar absorptivity values are 5.8 × 10⁴, 3.6 × 10⁴ and 4.8 × 10⁴ L/mol cm for methods A, B and C, respectively, and the corresponding Sandell’s sensitivities are 5.8 × 10^?3, 9.8 × 10^?3 and 7 × 10^?3 μg/cm², respectively. The developed methods are applied successfully to the determination of LZD in the pharmaceutical formulations and the results tallied well with label claims.     

Characterization of an extraction chromatographic resin for the separation and determination of 36Cl and 129I

The monitoring of long-lived radionuclides is of great importance in the context of the surveillance of nuclear facilities, during their operation as well as during their decommissioning. This is especially true for radionuclides of rather volatile elements, such as chlorine and iodine, the main interest being in ³⁶Cl and ¹²⁹I. Liquid Scintillation Counting (LSC) is a widely used measurement technique especially for the determination of ³⁶Cl that requires a thorough and selective sample preparation in order to give accurate results. Sample preparation methods frequently employed such as volatilization and/or repeated precipitation steps can be rather elaborate and time consuming. Therefore, an attempt has been made to develop an ‘easy to use’ extraction chromatographic resin that allows extraction, and subsequent separation, of chloride and iodide from pretreated environmental and decommissioning samples for their determination via LSC. First results of the characterization of the resin including D _w values of Cl^?, I^? and potential interferents, and of the method development are presented as well as the result of the analysis of a simulated real sample.     

Zur borbestimmung in silizium und germanium durch aktivierung mit protonen und deuteronen

The determination of boron via the nuclear reaction ¹¹B(p,n)¹¹C was studied in detail; the nitrogen reaction ¹⁴N(p,a)¹¹C interferes. Nitrogen also interferes deuteron activation via the nuclear reactions 10B(d,n)¹¹C and ¹¹B(d,2n)¹¹C, this interference must be attributed to the nuclear reaction ¹⁴(d,αn)¹¹C. Both interferences were investigated quantitatively. The conditions for the accurate determination of boron and for a simultaneous determination of boron and nitrogen by proton activation were established. An analytical method with chemical separation of the radioisotope ¹¹C was developed for silicon and germanium.     

The MEDINA facility for the assay of the chemotoxic inventory of radioactive waste packages

A new analytical facility called MEDINA (Multi Element Determination based on Instrumental Neutron Activation) and based on Prompt- and Delayed-Gamma-Neutron-Activation-Analysis (P&DGNAA) using a 14 MeV neutron generator is developed for the determination of non-radioactive elements and substances in 200-l radioactive waste drums. The qualitative performance of MEDINA is studied by measuring (1) the gamma-ray spectra for the empty chamber, (2) for an empty 200-l steel drum in presence or not of ⁶⁰Co and ¹³⁷Cs sources and (3) for a 200-l steel drum filled with concrete in order to determine the level of interferences induced by activation products of the facility components and to investigate further optimization steps to improve the measurements sensitivity. The measurement carried out for the empty drum with the radioactive sources show the possibility to characterize radioactive waste packages containing both ⁶⁰Co and ¹³⁷Cs with activities ranging between 20 and 80 MBq at least.     

Spectrophotometric determination of carbon disulphide as the 1,2,3,4-thiatriazol-5-thiolate ion

A simple, precise and selective procedure for the spectrophotometric determination of carbon disulphide in water is described. The method is based on the quantitative formation of the 1,2,3,4-thiatriazol-5-thiolate ion from carbon disulphide and azide. The specific rate for this reaction at ionic strength 4.0 (NaN₃) and 25°C is 8.4·10^-3 mol^-1 s^-1; the kinetic parameters D3H and D3S are 16.7 kcal mol^-1 and —14 cal mol^-1deg^-1, respectively. At the analytical wavelength of 313 nm, the molar absorptivity is 7.27 ·10³ l mol^-1cm^-1. The system obeys Beer's law for 2.3–28.6 g ml^-1 of carbon disulphide. The effects of foreign ions are discussed.     

The Determination of Impurities in 233UO2 by Spark Source Mass Spectrometry

Abstract

A method for the determination of impurities in ²³³UO₂ has been developed and applied to the analysis of a product stream of ceramic grade ²³³UO₂ powder. The analytical method has combined isotope dilution and internal standard methods to permit the determination of impurities at concentrations between 0.1 and 500 ppm in a single sample.     

General principles of enzymatic methods and their use in the determination of the radiochemical purity of mono-and disaccharides labelled with14C

General principles of enzymatic methods for the determination of radiochemical purity of natural¹⁴C-mono-and-disaccharides are suggested, and analytical schemes using these principles have been worked out. The enzymatic method of determining the radiochemical purity of¹⁴C-glucose is given as an illustration.     

Effect of Cetyltrimethyl Ammonium Bromide on Electrochemical Determination of Dexamethasone

The effect of surfactants on the electrochemical determination of dexamethasone at an edge plane pyrolytic graphite electrode (EPPGE), modified with single‐walled carbon nanotubes (SWNT) has been investigated. The unique electrocatalytic properties of SWNT along with the synergistic adsorption of CTAB on SWNT lead to sensitive voltammetric response of dexamethasone with the reduction peak at ca. ?1195 mV. The limit of detection and sensitivity of dexamethasone is estimated to be 9.1×10^?10 M and 0.727 µA µM^?1 respectively. The SWNT coated EPPGE had good stability and reproducibility. The analytical utility of the developed method was evaluated by applying it for sensing the drug in human body fluids and for the determination of dexamethasone content in several commercially available pharmaceutical preparations. A comparison of the observed results of proposed method with HPLC clearly indicates that the results of both the methods are in good agreement. The product obtained after the reduction of dexamethasone has also been characterized using ¹H NMR and carbonyl group at position 3 has been found to reduce. The method is instant, simple and accurate and can be easily applied for detecting cases of doping.     

Polarographic Determination of Inorganic Phosphorus in Phytic Acid

Abstract

A method for the determination of inorganic phosphorus in phytic acid by polarography was developed. The mechanism of Mo/Sb/P polarographic behaviour has been studied. It is one of the most sensitive analytical methods of phosphorus at present. The limit of detection is 8x10^?9 g/ml. This method has been used in the determination of inorganic phosphorus in phytic acid and result is found satisfactory.     

Determination of difficult to measure radionuclides in primary circuit facilities of NPP V1 Jaslovske Bohunice

Results of difficult to measure radionuclides in primary circuit facilities of nuclear power plant V1 in Jaslovske Bohunice (NPP V1) are presented. Samples from steam generator, main circulation pump and pressurizer were analyzed. Activity concentrations of ⁵⁵Fe, ^63,59Ni, ⁹⁰Sr, ⁹⁹Tc, ⁹³Mo, ⁹⁴Nb, transuranic elements were determined. Analytical and sampling methods are briefly described for the determination of difficult to measure radionuclides. The presented results have been successfully used for characterization of the waste during the decommissioning of NPP V1 nuclear reactors.     

Possibilities of the determination of3H,14C and131I individually and in mixtures,by the method of amplitude attenuation using liquid scintillators

Possibilities of the determination by radioactivity measurements of³H,¹⁴C and¹³¹I are described for the individual nuclides and their mixtures, with the use of liquid scintillators. The changes in the counting efficiency have been determined as a function of the parameters of the measuring equipment, and parameters are suggested which make possible the determination of³H,¹⁴C and¹³¹I individually, or in the pairs³H−¹⁴C,³H−¹³¹I,¹⁴C−¹³¹I, and finally, in the triplet³H−¹⁴C−¹³¹I.     

14C in spent ion-exchange resins and process water from nuclear reactors: A method for quantitative determination of organic and inorganic fractions

A method of separately quantifying organic and inorganic ¹⁴C compounds present in spent ion-exchange resins and process water from nuclear power reactors has been developed. Extraction of carbon compounds is accomplished by means of acid stripping (inorganic ¹⁴C) and subsequent wet oxidation (organic ¹⁴C) or by N₂ purging in combination with a catalytic furnace (oxidized and reduced gaseous compounds) with organic and inorganic ¹⁴C species collected separately. Recovery experiments on simulated samples spiked with ¹⁴C-labeled sodium carbonate, sodium acetate and sodium formate, showed extraction yields of 94–98%. The sample-specific procedures were also tested on authentic samples of spent resins and reactor water with good results. Validation and reliability of the procedures are presented and the method is compared to previous methods reported in the literature.     

Amorphous semiconductor thin films characterization by nuclear microanalysis

A review is presented summarizing the specific nuclear microanalysis methods applied in our laboratory to study amorphous semiconductor thin films. For backscattering, ∼3 MeV Li ions are applicable when depth resolution and sensitivity are required while up to 8 MeV α-particles allow larger depths to be probed and elemental interferences to be solved. These features are predominant for diffusion studies between metal electrodes and chalcogenide films. On the other hand hydrogen profiling using the¹H(^{1 5}N, αψ) resonant nuclear reactions is described and analytical problems associated with its use are discussed. Applications to the elaboration conditions of hydrogenated (a)Si is developed. Work supported by C.N.R.S. (A.T.P. Materiaux 2726 and Photovoltaique A 651 3865) and the C.E.A.—D.A.M. (contract No 1350)