Journal of Radioanalytical and Nuclear Chemistry

Sol–gel vitrification can be used to rapidly produce solid, vitreous materials to support nuclear forensics research. This work investigates three sol–gel synthetic approaches’ ability to retain fission products within the glass as a function of drying temperature. Eight of the ten fission products studied were quantitatively retained (less than 5% losses) at temperatures up to 600 °C for glasses prepared using an acidic catalyst and at temperatures up to 300 °C for glasses prepared using a basic catalyst. Both systems show partial loss of ruthenium and complete loss of iodine at temperatures above 300 and 100 °C, respectively.

Radiation detectors used to search for the existence of exceptionally rare phenomena, such as double-beta decay and dark matter interactions, as well as tiny traces of environmental radioactivity, require the elimination of background signals. Modern detection systems created from ultra pure materials and operated deep underground may be sensitive enough to “see” these rare phenomena, but background activity in Pb gamma-ray shielding could still be a critical stumbling block owing to alpha and beta emissions of Pb, Bi, and Po in the mass 210 chain. To minimize the probability of overwhelming activity from Pb, the alpha activity of 210Pb is quantified. However, a reliable quantification procedure that does not require large volumes of chemicals has not yet been established. Two procedures created for this purpose have been tested for the quantification of alpha activity in lead. Both procedures were designed to start with less than 10 g Pb samples to reduce reagents needed and combined precipitation with column separation to isolate 210Pb, followed by alpha spectrometry. One procedure shows promise for obtaining high recoveries and good separation.

Trace elements were determined by TXRF in whole blood samples in a randomly non-occupational exposed population living in the Metropolitan Zone of the Mexico Valley (MZMV). Arithmetic and geometric means of S, Ca, Cu, Zn, Rb and Pb concentrations, were on the reported range values for non-occupational population in other countries, while those of K and Br were higher, possibly due to dietary habits and geographical or environmental factors. The noticeable decline in blood lead level (91%) should be positively perceived. As a part of the Quality Control Program, a certified IAEA-A13 was tested.

More than 2200 atmospheric particulate matter filters were collected from 1995 through 2002 in the Spokane, WA area for the Spokane Air-Filters Project. The samples were sent to the US EPA in Research Triangle Park, NC for energy dispersive X-ray fluorescence (XRF) analysis and then delivered to the Washington State University Nuclear Radiation Center for neutron activation analysis (NAA). There were 28 elements of interest for the NAA portion of the project; however, due to detector efficiencies, background effects, and composition loading on each filter, only 15 of the 28 elements analyzed for produced valid results above the detection limit due to Compton background noise and blank subtraction. The 15 detectable elements with their six year average with associated 95% confidence interval concentrations in ng/m3 are: As (0.384±0.88), K (50.0±194), La (0.051±0.251), Na (61.9±421), Sm (0.00928±0.072), Au (0.00154±0.149), Br (1.06±1.5), Ce (0.164±0.969), Co (0.0399±0.122), Cr (0.479±3.31), Fe (110±227), Sb (0.474±1.64), Sc (0.0197±0.00548), Th (0.011±0.0603), and Zn (12.4±32.6).

The determination of isotopic thorium by alpha spectrometric methods is a routine practice for bioassay and environmental measurement programs. Alpha-spectrometry has excellent detection limits (by mass) for all isotopes of thorium except 232Th due to its extremely long half-life. This paper discusses improvements in the detection limit and sensitivity over previously reported methods of pre-concentration neutron activation analysis (PCNAA) for the recovery corrected, isotopic determination of thorium in various matrices. Following irradiation, the samples weredissolved, 231Pa added as a tracer, and Pa isolated by two different methods and compared (extraction chromatography and anion exchange chromatography) followed by alpha spectrometry for recovery correction. Ion exchange chromatography was found to be superior for this application at this time, principally for reliability. The detection limit for 232Th of 3.5 · 10-7 Bq is almost three orders of magnitude lower than foralpha spectrometry using the PCRNAA method and one order of magnitude below previously reported PCNAA methods.

Solvent extraction of thorium (IV) from aqueous solution with dialkyldithiophosphoric acids (RO)2P(S)SH, (abbreviated Hdtp) in different organic solvents shows that the chain length in Hdtp significantly influence the magnitude of the distribution ratio. The diluent effect and the influence of the inorganic anion present in the aqueous phase was investigated in the Th — di (2-ethyl-hexyl) dithiophosphoric acid (HEhdtp) extraction system. The treatment of the partition data shows that the extraction of Th(IV) in benzene, cyclohexane, chloroform, carbon tetrachloride and n-butanol from perchlorate, chloride and nitrate media occurs via an ion-exchange mechanism. Inorganic anions present in the aqueous phase do not participate in the formation of the extracted species but influence the magnitude of the distribution ratios.

A rapid and comprehensive method has been developed for the determination of ppm to sub-ppb amounts of Ru, Pd, Ag, Os, Ir, Pt and Au, based on thermal neutron irradiation, dissolution of samples, selective absorption on Srafion NMRR ion exchange resin and high resolution γ-ray spectrometry. Two noble metals “specific” resins were tested for their absorption behaviour. The method has been used for analysis of standard rocks, ores, minerals, lunar samples, coal, coal fly ash, and several biological materials.

We have developed a sequential extraction technique for determining the geochemical partitioning of Am, Pu, and U in soils and sediments. Stable element analyses were combined with radiometric measurements to determine the most probable geochemical host phases of these actinides in reference sediment IAEA-135.241 Am results indicate an association with carbonate minerals and organic matter. The extraction profile of238U was similar to that of refractory elements Al, Ti, and K.239/240Pu data suggest a fractionation of Pu into Fe-bearing phases of varying solubility. The reproducibility of the method was quite good (replicates agreed to within 10% at a 95% confidence level).

Radioiodinated insulin and thyroid stimulating hormones were prepared using 1,3,4,6-tetrachloro-3α, 6α-diphenylglycouril (Iodogen). Conditions of iodination like concentration of iodogen, reaction time, etc., were optimized to get maximum yield. Stability studies of iodogen coated tubes were carried out over a period of time. The dependence of iodination yield on varying amounts of activity and protein concentration were investigated. Iodination yield over a range of pH was also studied. The radiolabelled hormones prepared by this method were used in radioimmunoassay and were compared with tracers prepared by the Chloramine-T method.