Lead phosphate quantitatively coprecipitates trace amounts of Ag(I), Cd(II), Cr(III), Cu(II), Mn(II), Th(IV), U(VI) and Zr(IV).
The trace elements are determined in the precipitate by instrumental neutron activation analysis (INAA); detection limits
are given. The practical application to the determination of U and Th is described.
The dependence of self-absorption of X-rays and low energy -rays on energy and sample matrix has been studied for94mNb,128I,104mRh,239U and233Th. Experimentally determined attenuation factors have been compared to calculated values. The use of these nuclides in the instrumental neutron activation of practical samples has been evaluated.
An instrumental neutron activation analysis procedure has been developed which permits the direct determination of Au, Ir, Os and Rh in iron meteorites using a SLOWPOKE reactor. A simple correction method enables the instrumental determination of rhodium using its short-lived nuclide.
X-rays emitted by thallium and bismuth after neutron activation have been examined for their use in the determination of these elements. Interferences have been assessed. Thallium-204,206Tl and210Bi are employed. Detection limits are high but purely instrumental determinations are possible from 50 g per g to fractions of percent levels.
Authors:S. Muddukrishna, J. Holzbecher, and D. Ryan
Hair samples from Canada, China, India and New Zealand were analyzed by neutron activation analysis. Comparison of the percent manganese in the alkali-soluble fraction of hair with the total manganese concentrations shows that, within groups, the percent manganese concentrations is relatively constant whereas overall concentrations are not. For multiple sclerosis (MS) patients, from Canada and New Zealand, very highly significant differences were observed, between controls and patients, for %Mn in the alkali-soluble fraction.
Authors:G. Solano, S. Katz, J. Holzbecher, and A. Chatt
Reference materials for the speciation and quantification of chromium in contaminated soils were prepared by impregnating diatomaceous earth with BaCrO4 and Cr2O3. The chronium concentrations of these materials were confirmed to be 200 mg/kg both by atomic absorption spectrometry and by instrumental neutron activation analysis, but monthly assays over two calendar quarters of the reference material impregnated with BaCrO4 revealed the hexavalent chromium was not stable in this matrix.
Authors:Y. Serfor-Armah, B. Nyarko, J. Holzbecher, E. Akaho, E. Osae, and A. Chatt
Epithermal instrumental neutron activation analysis (EINAA) together with Compton suppression system were optimized and used to analyze several food samples for the determination of low levels of iodine. The method involved the irradiation of samples in the outer epi-cadmium site of the Dalhousie University Slowpoke-2 reactor facility. The samples were then counted directly without any chemical treatment on an anticoincidence counting system. This system comprised a 25 cm3 hyperpure Ge detector, a guard detector consisting of a 10"×10" NaI(Tl) annulus with five photomultiplier tubes (PMTs) and a 3"×3" NaI(Tl) plug with one PMT. Iodine was quantitatively analyzed using the 443 keV photopeak of 128I. The precision and accuracy of the method were evaluated using real samples and biological reference materials, respectively. The precision of the method was calculated as percent relative standard deviation and in all cases was within ±5%. The agreement between our iodine values and those of the certified values was generally within ±10%, suggesting an excellent accuracy of the method. The detection limits of the various samples calculated, with the lowest value of 20 ppb. The values of iodine determined ranged between 24 to 3080 ppb. The methods and results are presented.
Authors:B. Nyarko, Y. Serfor-Armah, J. Holzbecher, E. Osae, E. Akaho, D. Carboo, and A. Chatt
Epithermal instrumental neutron activation analysis (EINAA) together with both conventional and anti-coincidence counting techniques were used to analyze six different gold tailing samples from Ghana for Au and As. The method involves the use of the epi-cadmium site of the Dalhousie University Slowpoke-2 reactor facility for the irradiation of the samples. After irradiation, the samples were counted directly on the detectors. The identification and quantification of the elements were done using 411 keV photopeak of 198Au and both 559 keV and 657 keV photopeaks of 76As. The precision and accuracy of the method were evaluated. Values for Au in the samples ranged from 2.48 ppm and 6.76 ppm and for As between 1,550 ppm and 3,460 ppm. The values obtained using the two counting systems were in good agreement while the anti-coincidence counting system gave values of higher precision and accuracy. The detection limit for Au were 20 and 10 ppb for the conventional and anti-coincidence spectrometric systems, respectively, and 50 ppb for As in both cases. Details of the method and results are presented.