A novel dibenzo-18-crown-6 ether (DB-18CE-6)- functionalised silica (SiO2) disk was found to be a capable
source preparation technique for the rapid analysis of 226Ra by alpha-spectrometry. DB-18CE-6 was chemically
immobilised onto the surface of SiO2 disks. It is anticipated that the high levels of selectivity of DB-18CE-6 for
radium will allow for an efficient chemical separation of 226Ra from other elements present in sample matrices.
226Ra was adsorbed as a monolayer onto the surface of the silica disks, attaching to the functionalised centres of
the DB-18CE-6 structure, forming a high resolution counting source for alpha-spectrometry. The chemical
recovery of radium from synthetic samples was 2.3% at pH 2, with higher recoveries expected over the pH range
Van Es Elsje, Hinchliff J., Felipe-Sotelo Monica, Milodowski A.E., Field L.P., Evans N.D.M., Read David (2015) Retention of chlorine-36 by a cementitious backfill, Mineralogical Magazine 79 (06) pp. 1297-1305
The Mineralogical Society of Great Britain and Ireland
Radial diffusion experiments have been carried out to assess the migration of 36Cl, as chloride, through a cementitious backfill material. Further experiments in the presence of cellulose degradation products were performed to assess the effect of organic ligands on the extent and rate of chloride diffusion. Results show that breakthrough of 36Cl is dependent on chloride concentration: as the carrier concentration increases, both breakthrough time and the quantity retained by the cement matrix decreases. Experiments in the presence of cellulose degradation products also show a decrease in time to initial breakthrough. However, uptake at various carrier concentrations in the presence of organic ligands converges at 45% of the initial concentration as equilibrium is reached. The results are consistent with organic ligands blocking sites on the cement that would otherwise be available for chloride binding, though further work is required to confirm that this is the case. Post-experimental digital autoradiographs of the cement cylinders, and elemental mapping showed evidence of increased 36Cl activity associated with black ash-like particles in the matrix, believed to correspond to partially hydrated glassy calcium-silicate-sulfate-rich clinker.
Accurate, low-level measurement of 226Ra in high volume water samples requires rapid pre-concentration and robust separation techniques prior to measurement in order to comply with discharge limits and drinking water regulations. This study characterises the behaviour of 226Ra and interfering elements on recently developed TK100 (Triskem International) extraction chromatography resin. Distribution coefficients over a range of acid concentrations are given, along with an optimised procedure that shows rapid pre-concentration and separation of 226Ra on TK100 resin is achievable for high volume (1 L) water samples without the need for sample pre-treatment.
A novel and rapid method has been developed for pre-concentration and measurement of 226Ra in groundwater and discharge water samples using the latest generation triple quadrupole inductively coupled plasma mass spectrometry (ICP-QQQ-MS). Cation exchange and extraction chromatography are capable of pre-concentration factors of ~200 based on 1 L samples. The sensitivity and interference removal capability of ICP-QQQ-MS was assessed from spiked groundwaters, with the introduction of He collision gas required to minimise instrument background in high-matrix samples. The technique developed is potentially capable of detecting 226Ra activities as low as 5 mBq L?1 when combined with pre-concentration prior to measurement.
Thorium-227 is currently undergoing evaluation as a potential radionuclide for targeted cancer therapy, and as such a high chemical purity of the material is required. To establish a reliable procedure for radiochemical isolation of 227Th from the parent 227Ac and decay progeny, which includes the radiotherapeutic 223Ra, the performance of three different separation schemes based on ion-exchange and extraction chromatography have been evaluated. The results suggest that both ion exchange and extraction chromatographic techniques can be successfully used for the separation of 227Th from its decay progeny, however extraction chromatographic resins demonstrate favourable performance in terms of Th recovery and purification from radionuclide impurities.