The analytical procedure established in the present work is as follows; The crushed rock samples of 1 g were sealed in polyethylene vials and irradiated in the pneumatic tube of the JRR-2 reactor at a flux of 8×1013 n/cm2·sec for 20 min. Samples and monitors were fused with sodium hydroxide in nickel crucibles, in the presence of carriers. The fusion cake was dissolved in water and acidified to about 2M H2SO4. Fe3+ was added to oxidize I- to I2, and I2 was distilled into sodium sulfite solution. KMnO4 was then added to oxidize Br- and Cl- to Br2 and Cl2, and these elements were separated from mother solution by distillation. Chemical yields were measured colorimetrically for iodine and potentiometrieally for chlorine and bromine. Yields consistently ranged from 80%-90% and time required for chemical separation was about 50 min. The distillates were counted on a γ-ray spectrometer, consisting of 3in.×3in. NaI (Tl) crystal and a 400-channel pulse height analyser. The following γ-rays were measured: 128I, 0.445 MeV; 38Cl, 1.60 and 2.17 MeV; 82Br, 0.55 and 0.78 MeV. The activity measurement for 82Br was done after one day cooling. Interference from (n, p), (n, α), (n, 2n) and fission reactions was negligible. The present method was applied to sedimentary rock samples of Niigata prefecture and highly reproducible results were obtained. The sensitivity is 10-8g for iodine, 10-7g for chlorine and bromine.
67Ga-citrate is used for the clinical scanning of the malignant tumor, and affinity of111In-chloride for the malignant tumor is reported by W.H. Hunter, et al. But the mechanism of their affinity for tumor is unknown. In order to investigate the mechanism of the accumulation of these elements in tumor, affinity for the malignant tumor of radioactive gallium, indium and scandium (the elements of group III in the periodic table) were examined, using the rats which were subcutaneously transplanted with Yoshida sarcoma. In this experiment, several kinds of compound of gallium and indium had strong affinity for the malignant tumor, but scandium compounds had not affinity for the malignant tumor. These compounds which had strong affinity for the malignant tumor were those which were under carrier free state and became gallium-ion or indium-ion easily in the body. Gallium compounds containing little carrier had still strong affinity for tumor but indium compounds with carrier had not affinity for tumor even if amount of carrier was small. Gallium compounds and indium compounds suitable for the selective uptake by the malignant tumor have very strong affinities to the malignant tumor and their retention values in the tumor showed approximately the same, but the retention values in the blood and kidney were larger in indium than in gallium. From these experimental results, it is thought that gallium is more excellent for tumor detection than indium.
Purity test of seven kinds of radiopharmaceuticals was examined by using paper and thin-layer chromatographic techniques and paper electrophoretic method. On paper chromatography, the most suitable solvents were shown as below; for cesium chloride and rubidium chloride: acetone/HCl/aq. dist.=4: 1: 3 for chlormerodrin: dimethylformamide/aq. dist./methanol=5: 1: 14 for merisoprol and sodium pertechnetate: 70% methanol. In the case of iodoantipyrin, paper chromatography was not suitable, but only thinlayer chromatography gave satisfactory result with a mixture of ethanol-benzene=2: 1. Electrophoresis with veronal buffer solution have proved most useful in the separation of macro aggregated human serum albumin and human serum albumin. The latter traveled further than the former which remained on the spotted origin under the same condition.