Immunological studies have often been based on the results of cytolytic assay in which cells labelled with radioactive51Cr are usually employed. The replacement of the radioactive isotope by a stable one is obviously desirable in order to eliminate the problem of radiation hazard and to prevent environmental contamination. We applied PIXE (particle induced X-ray emission) method for the detection of stable chromium (Cr) . MM46 cells labelled with natural Cr were treated with anti-MM46 serum and a rabbit complement. The remaining Cr was filtered. The released Cr was precipitated with ethanol and deposited on the filter. The specimens were bombarded with proton beams from a Van de Graaff accelerator and the X-rays produced were detected with a Si (Li) detector. The Cr peaks appeared clearly. One of the main advantages of the application of the PIXE method is its high sensitivity. Another merit of the present method is that it can easily compare the remaining ratio of several elements in cellular materials after lytic treatment. This information may be used as a parameter indicating differences in the process of cytolysis.
In order to study the metabolism of cianidanol (I), [3-2H] - (I) and [3-3H] - (I) were synthesized. (I) was benzylated and then oxidized with DMSO-Ac2O to give 2R-3', 4', 5, 7-tetrabenzyl-cianidan-3-one (III) . (III) was reduced with NaB2H4or NaB3H4, and then debenzylated to give [3-2H] - (I) or [3-3H] - (I) . [3-2H] - (I) was obtained with the over all yield of 21% from NaB2H4. In the other hand, [3-3H] - (I) was obtained with the over all yield of 23% from NaB3H4.
A method for the redox substoichiometric determination of thallium employing chlorate as an oxidant has been developed. The substoichiometric amount of Tl (III) formed was isolated by extraction with isoamyl acetate. 5-50μg of thallium can be determined with an accuracy of ±1.3%.
By sodium nickel ferrocyanide coprecipitation, 60Co and137Cs are simultaneously collected by nearly 99% recoveries from the unaged seawater. But this coprecipitation is not effective for the recovery of the60Co complexed with organic ligands which would exist in natural seawater. In order to obtain the effective recoveries for these complexed60Co, various pretreatments were investigated by using model samples containing the60Co aged with several amino acids. In the acidification of these samples by nitric acid as 1 pretreatment, a large portion of these complexed60Co was dissociated, especially by heating samples at 90-95°C. The recoveries of60Co were ranging from 90 to 97%. On the other hand, the usage of potassium peroxodisulfate (4.0×10-4-2.0×10-2M) as another pretreatment method elevated the recoveries of these complexed60Co by more than 99% by heating samples above 90°C. These 2 pretreatment methods were also effective for recoveries of137Cs ion.