In the present work an improvement of radiochemical neutron activation analysis for determination of nanogram levels of vanadium is described. The method is based on post-irradiation wet ashing and solvent extraction of vanadium with N-benzoyl-N-phenyl-hydroxylamine (BPHA) forming a violet chelate complex in strongly acidic medium. For quality assurance purposes a procedure for determination of the overall chemical yield using spectrophotometry of the V-BPHA complex is described, and possible interferences are evaluated. The procedure was applied to the determination of vanadium in reference materials and selected food samples from Slovenia.
A radiotracer method is described for measurement of the chemical yield in radiochemical neutron activation analysis of selenium using the75Se (120 d) induced nuclide. It is based on81mSe (57 min) radioisotopic tracer, prepared immediately before its use in the radiochemical separation procedure, by neutron irradiation of highly enriched80Se. The recovery of selenium is calculated from the 103 keV -peak of81mSe in the separated selenium fraction used for quantitation of75Se. The technique is illustrated by results for biological reference materials of good accuracy and reproducibility.
Authors:R. Jaćimović, P. Makreski, V. Stibilj, and T. Stafilov
Major and trace element contents in iron ore reference materials were investigated using k0-instrumental neutron activation analysis (k0-INAA). To avoid iron interferences, radiochemical separation was developed (k0-RNAA). The determination of the investigated elements in the inorganic phase from hydrochloric acid solution was performed
after radiochemical separation of iron by diisopropyl ether. It was found that after the Fe elimination, the limit of detection
for some elements was much lower that enables their direct determination. The distribution of 39 elements (with intermediate/medium
and long half-life radionuclides) after Fe removal was investigated.
Authors:R. Jaćimović, V. Stibilj, L. Benedik, and B. Smodiš
The neutron distribution in a defined volume (gradient) for different matrices (air, water, cellulose, biological material and silicon dioxide) in two typical irradiation channels (pneumatic tube (PT) and IC40-channel in the carousel facility) in the TRIGA Mark II reactor at the Joef Stefan Institute (IJS) was studied. Our experiment was based on inserting Fe wires (flux monitors) into the chosen matrices. The wires were cut into small pieces after irradiation and the induced activities of 59Fe measured. The results showed that for the studied geometry the average spatial thermal neutron flux inhomogeneities (for five studied matrices) are about 2.3% in the PT-channel and about 2.9% in the IC40-channel.