Within this work the analysis of the kinetic stability of a series of yttrium complexes, i.e., Y-citrate, Y-NTA, Y-CDTA as
well as Y-humic acid (Y-HA) has been successfully performed by the free-ion selective radiotracer extraction (FISRE) method.
FISRE uses 90Y with a high specific activity to perform CHELEX extractions in a buffered aqueous solution at pH 6 in two different modes
by monitoring the dissociation and association reactions of the corresponding complexes. Whereas in the case of Y-citrate
the dissociation profile could be successfully described in terms of (pseudo) first order kinetics, the other complexes tend
to form two species with different kinetic properties, although only one species is predicted by speciation calculations.
In the batch FISRE method, all (except Y-NTA) corresponding association rate constants were determined by monitoring the formation
rate of the yttrium complexes.
Representative banded iron-formations (BIFs) from various locations of the eastern Indian geological belt were investigated
by instrumental neutron activation analysis (INAA). After pre-concentration, irradiation was carried out using a neutron flux
of 5.1·1016 m−2·s−1, 1.0·1015 m−2·s−1 and 3.7·1015 m−2s−1, with thermal, epi-thermal and fast neutrons, respectively. The activities in these samples were measured by a HPGe detector.
Ten rare-earth elements, such as La, Ce, Nd, Sm, Eu, Tb, Ho, Tm, Yb and Lu, have been qualitatively identified and quantitatively
estimated in these samples. The present investigation is an example of employing a pre-concentration method for high iron-containing
ores prior to neutron activation analysis.
A bipolar electrolysis system for tritium accumulation and HTO waste volume reduction was designed and built. Experiments
were performed to achieve the system specific separation factor for iron and stainless steel cathodes in a 1M sodium hydroxide
solution. A separation factor of about 6 for stainless steel and 19 to 26 for iron was measured. The vapor pressure isotope
effect under experimental conditions was determined as 1.09±0.03 (T = 279 K).
Authors:B. Wierczinski, G. Müllen, and S. Rosenhauer
Cryosublimation is one technique, which allows the accumulation of tritium from aqueous solutions using certain chemical compounds.
After studying several inorganic compounds such as zeolites and metal salts,1 as well as some humic substances,2 we have now investigated several mono-and polysaccharides, such as glucose, maltose, galactose, starch, agar, and gelatine.
Except for starch all of the above mentioned compounds showed a clear enrichment of tritium. The highest value was reached
for Agartine, which gave an enrichment factor of 6.2. Since mono-and polysaccharides form weak hydrogen bonds, these results
prove again our theory that tritium is preferably accumulated in exchangeable hydrogen bonds.
Authors:D. Jurkin, F. Gildehaus, and B. Wierczinski
Due to physical decay properties commonly associated with therapeutic radionuclides, 188Re (t1/2 = 16.98 h, Emax = 2.12 MeV) is of high interest for endovascular brachytherapy and endoradiotherapy in general. Rhenium precursors in the
low oxidation state +I, such as the organometallic fac-[Re(H2O)3(CO)3]+ are promising lead compounds compared to those with oxidation states +III and +V since they can be prepared under mild conditions
and do not tend to reoxidize to oxidation state +VII while multidentate ligands can be attached under substitution of coordinated
water molecules. This study comprises the application of the Free-Ion Selective Radiotracer Extraction (FISRE) technique in
order to determine dissociation rate constants of complexes bearing the [188Re(CO)3]+-core at tracer levels in vitro with regards to their time-dependent kinetic speciation. As ligands, the tridentate l-histidine as well as the dipeptides l-carnosine (β-alanyl-l-histidine) and glycyl-l-histidine were chosen in order to study the effects of different moieties attached to the primary amine of l-histidine.
Authors:B. Wierczinski, J. Aign, F. Baumgärtner, G. Müllen, and A. Türler
Tritium exchange and enrichment was studied for several different metal salts, e.g., AlF3 . H2O, FeO(OH), CsI, CsF, NaI, NaF and Al(OH)3 using a cryosublimation apparatus. Experiments were performed below equilibrium vapor pressure to avoid any isotope effects. A comparable tritium enrichment factor of 1.14 to 1.43 was obtained for all systems, except for CsF, which gave an enrichment factor of 1.93. These results confirm the concept, that 3H is accumulated in weak hydrogen bonds as already observed in organic molecules.
Authors:M. Johansson, R. Malmbeck, B. Wierczinski, and G. Skarnemark
A study of the extraction of polonium from aqueous solutions containing -hydroxyisobutyric acid (-HIBA) was performed with four different extractants, di-n-octyl sulphide (DOS), Cyanex 272, Cyanex 301 and Cyanex 302, dissolved in toluene. The extracted complex for DOS at low -HIBA concentrations is most likely PoO(-HIB)2·2DOS, while at higher -HIBA concentrations there seems to be a solvating effect implicating an extracted complex of the type PoO(-HIB)2(-HIBA)2·2DOS. For the extraction of polonium with Cyanex 272 the results are inconclusive. The extracted complex is either PoOA2 or PoO(-HIB)2·2HA. For extraction with Cyanex 301 or Cyanex 302 the major extracted species does not contain any -HIBA molecules. The neutral species in both cases is PoOA2, extracted at low extractant concentrations, while at higher extractant concentrations a complex of the type PoOA2·xHA is extracted. The extraction of polonium increases in the order Cyanex 272 < DOS < Cyanex 302 < Cyanex 301.
Authors:Y. M. Efimova, B. Wierczinski, S. Haemers, and A. A. van Well
Bovine serum albumin (BSA) and lysozyme (LSZ) were radiolabeled with 125I. Three different methods for protein iodination with 125I were optimized. Parameters like incubation time and ratio of oxidizing agent and amount of protein were established. During protein iodination with 125I, structural damages caused by the introduction of iodine into the protein may occur. These damages depend on the oxidizing agent used and may lead to considerable changes in the protein structure and, hence, their biological activity. Changes in secondary structure of LSZ and BSA were examined by circular dichroism (CD). Enzymatic activity tests were performed with lysozyme to check its biological activity. The Iodo Bead was found the best oxidizing agent for protein iodination.
Authors:B. Wierczinski, J. Alstad, K. Eberhardt, J. Kratz, R. Malmbeck, M. Mendel, A. Nähler, J. Omtvedt, G. Skarnemark, N. Trautmann, and N. Wiehl
Fast solvent extraction is a chemical separation method, which can be applied to study exotic nuclides. Since about 1970 the
SISAK technique, which is an on-line method based on multi-stage solvent extraction separations, has been successfully used
to investigate the nuclear properties of β-decaying nuclides with half-lives down to about one second. During the last decade
it has become possible to produce transactinide elements in high enough yields to investigate their chemical properties on
a one-atom-at-a-time scale. For this purpose it was necessary to improve and change the detection part of the SISAK system
in order to be capable to detect spontaneously fissioning and α-decaying nuclides in a flowing organic solution. This technique
is based on liquid scintillation counting with pulse-shape discrimination and pile-up rejection
Authors:B. Wierczinski, K. Gregorich, B. Kadkhodayan, D. Lee, L. Beauvais, M. Hendricks, C. Kacher, M. Lane, D. Keeney-Shaughnessy, N. Stoyer, D. Strellis, E. Sylwester, P. Wilk, D. Hoffman, R. Malmbeck, G. Skarnemark, J. Alstad, J. Omtvedt, K. Eberhardt, M. Mendel, A. Nähler, and N. Trautmann
Subsecond 224 Pa (T1/2 = 0.85 s) was produced via the 209 Bi(18 O,3n)224 Pa reaction at the 88 inch cyclotron at the Lawrence Berkeley National Laboratory. After production it was transported via a gas-jet system to the centrifuge system SISAK 3. Following on-line extraction with trioctylamine/scintillation solutions from 1M lactic acid, 224 Pa was detected applying on-line -liquid scintillation counting. Unambiguous identification was achieved using time-correlated --decay chain analysis. This constitutes the first chemical on-line separation and detection of a subsecond -decaying nuclide, 0.85-s 224 Pa with the fast extraction system SISAK 3.