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A newly devised, very accurate (“definitive”) method for the determination of trace amounts of cobalt in biological materials
was validated by the analysis of several certified reference materials. The method is based on a combination of neutron activation
and selective and quantitative postirradiation isolation of radiocobalt from practically all other radionuclides by ion-exchange
and extraction chromatography followed by γ-ray spectrometric measurement. The significance of criteria that should be fulfilled
in order to accept a given result as obtained by the “definitive method” is emphasized. In view of the demonstrated very good
accuracy of the method, it is suggested that our values for cobalt content in those reference materials in which it was originally
not certified (SRM 1570 spinach, SRM 1571 orchard leaves, SRM 1577 bovine liver, and Czechoslovak bovine liver 12-02-01) might
be used as provisional certified values. 相似文献
2.
Since 1983, prenatal diagnosis of Menkes disease has been carried out by determining Cu in samples of chorionic villi from
the fetus by means of radiochemical neutron activation analysis. Concentrations of Cu in chorionic villi from male fetuses
later confirmed to have Menkes disease were invariably higher than previously reported values for normal controls. Out of
240 samples analyzed in the period 1983–1998, there were 71 from female fetuses that could be carriers of the Menkes genetic
defect without suffering from the disease. Increased concentrations of Cu in these samples could not be attributed to the
presence of this genetic defect, but might result from sporadic contamination of the samples before analysis. Such contamination
also may occur in samples from male fetuses and thus raise the level of Cu in small, but normal specimens into the range characteristic
of Menkes disease. In spite of a strict protocol for taking samples without contamination, a total of four false positives
were reported during the period of investigation; no false negatives have occurred. 相似文献
3.
Elemental concentration of selenium in bovine plasma at partsper-billion levels was determined using radiochemical neutron
activation analysis (RNAA). This study was connected with the relation between the Enteque Seco, a toxic bovine calcinosis,
and the Se status. The technique developed is based on the coprecipitation of Se with HgS. Good agreement with certified reference
materials have been found. The values for the Se contents in normal bovine samples were in concordance with literature values. 相似文献
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