The Rare-Earth Elements (REE) distribution pattern, along with the
206
Pb/
204
Pb,
207
Pb/
204
Pb and
208
Pb/
204
Pb isotopic ratios, can assist nuclear forensics practitioners and safeguards in ...tracing a uranium nuclear material back to its origin or in verifying the declared origin or accountancy. The present paper shows the first "in-house" analytical method, developed within the "Horia Hulubei" National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH), with the purpose of monitoring REE and lead impurities in uranium oxide samples. A total of nine spiked replicate samples and three subsamples of UO
2
Merck testing material were subject to the developed procedure. The method was validated in terms of selectivity, trueness (recovery), determination of the quantification limit, precision (repeatability) and ruggedness, proving that is suitable for monitoring REE and lead impurities in the tested matrix.
In the context of the Collaborative Materials Exercise CMX-7 organized by the Nuclear Forensics International Technical Working Group (ITWG), four sample of uranium materials were analysed by ...IFIN-HH, Romania. The presented work is focused on presenting the analytical process of adapting a SQ ICP-MS such that to be used for determining fingerprints of the nuclear materials of interest. The “in-house” protocol developed made possible the determination of the uranium isotopic ratio of the samples without the use of chemical separation and also to determine the concentration of the trace elements. The age determination calculated based on the
230
Th/
234
U chronometer.
Novel planar glucose biosensors to be used for continuous monitoring have been developed. The electrodes are produced with the “screen printing” technique, and present a high degree of ...reproducibility together with a low cost and the possibility of mass production. Prior to enzyme immobilisation, electrodes are chemically modified with ferric hexacyanoferrate (Prussian Blue). This allows the detection of the hydrogen peroxide produced by the enzymatic reaction catalysed by GOD, at low applied potential (ca. 0.0
V versus Ag/AgCl), highly limiting any electrochemical interferences. The layer of Prussian Blue (PB) showed a high stability at the working conditions (pH 7.4) and also after 1 year of storage dry at RT, no loss of activity was observed. The assembled glucose biosensors, showed high sensitivity towards glucose together with a long-term operational and storage stability. In a continuous flow system, with all the analytical parameters optimised, the glucose biosensors detected glucose concentration as low as 0.025
mM with a linear range up to 1.0
mM.
These probes were also tested over 50–60
h in a continuous flow mode to evaluate their operational stability. A 0.5
mM concentration of glucose was continuously fluxed into a biosensor wall-jet cell and the current due to the hydrogen peroxide reduction was continuously monitored. After 50–60
h, the drift of the signal observed was around 30%.
Because of their high stability, these sensors suggest the possibility of using such biosensors, in conjunction with a microdialysis probe, for a continuous monitoring of glucose for clinical purposes.
This paper reports the results of radiological measurements taken for the last 3 years in the controlled area and adjacent zone of the Tritium Laboratory of the the Horia Hulubei National Institute ...for Physics and Nuclear Engineering, Magurele. The radiological characterization has been performed by determination of total and removed tritium contamination for the following surfaces: pavement, walls, windows, radiochemical tables, radionuclide fume cupboards, glove boxes, and sinks. The fixed tritium contamination does not present representative radiological risk because beta particles emitted by tritium are unable to penetrate the skin. The removed tritium contamination represents that component of the total surface contamination that can be taken by mechanical processes. The removed contamination was analyzed as a priority because it represents the main radiological risk factor in tritium laboratories. The determination of surface contamination has been carried out by scanning of the analyzed surfaces using an LB 1230 UMo tritium surface monitor with an LB 1230 detector and by a smear test using extruded polystyrene smears followed by measurement of the removed activity with a liquid scintillation counter. The total surface contamination values, obtained by scanning, were below the detection limit of the equipment, except for radiochemical hood surfaces. The removed tritium contamination determined values are in the domain of 5 ... 450 Bq/dm
2
. At the department level, the obtained values for surface tritium contamination are at the background level.
Annual tritium exposures can be reconstructed for long time periods by analyzing radioactive concentrations in tree rings near nuclear facilities that can release tritiated water (HTO) to the ...environment. Since the mass of analyzed samples is on the order of milligrams, usual methods such as liquid scintillation counting cannot be applied. The recommended method comprises thermal decomposition of the milligram-sized samples, reduction of the resulting HTO to tritiated hydrogen, quantitative absorption of titanium hydride (TiHT) in titanium powder, and determination of the H/T ratio using an accelerator mass spectrometer method. This paper describes the method for obtaining TiHT standards with different H/T isotopic ratios for calibration of a mass spectrometer detector.
The addition to the carbon ink, a major component of a screen-printed electrode (SPE), of an aliquot (10%) of Prussian Blue (PB)-modified glassy carbon (PB-GC) particles, resulted in an interference ...free “ready to use” amperometric H
2O
2 sensor (
V
app=−50
mV) with a LOD of 3×10
−7
mol/l and a sensitivity of 135
mA (mol
l
−1
cm
2). A storage stability of up to 8 months and an operational stability of 3 days has been achieved making these sensors suitable for mass-production.
Glucose and lysine biosensors have been assembled immobilizing glucose oxidase (Gox) and lysine oxidase (LyOx) with glutaraldehyde and Nafion
® onto the PB bulk-modified electrodes. A LOD of 4×10
−6
mol/l for glucose and 5×10
−6
mol/l for lysine with a linear range up to 0.5 and 0.7
mmol/l, respectively, have been observed.
A ready to use glucose biosensor was then developed mixing PB-modified glassy carbon (7.5%), carbon ink (87.5%) and glucose oxidase (GOx, 5%) and using the mixture for the printing step of a SPE working electrode. A LOD of 3×10
−5
mol/l and a linearity range up to 6×10
−3
mol/l of glucose have been achieved, together with a storage stability up to 20 weeks (at RT) and an operational stability of 1 day with 11 calibration curves performed.
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