Abstract
The 0.5-g samples of seed, stem, leaf, chaff and grain collected from a batch of rice plant were activated with thermal neutrons in an atomic reactor for 30 min. After the activation the samples were decomposed by a conc. H2SO4 and conc. HNO3 mixture together with KCl, KBr, and KI carriers. During the process the distillate was absorbed in a cold 5N NaOH solution, Then iodine was isolated by a reduction procedure with hydrazine sulfate and a following oxidation with sodium nitrite in nitric acid medium, and extracted into a CCl4 phase. A gamma-ray spectrometry of 128I had been done on the AgI precipitate obtained through a back-extraction of iodine from the CCl4 to an aqueous phase containing Na2SO3. For the other two elements a mixed precipitate of AgBr and AgCl was produced from the remaining aqueous phase after the iodine extraction. And immediately a gamma-ray spectrum of 38Cl was measured. After the 38Cl decay, that is one day interval, a spectrum of 82Br could be measured on the same precipitate. The chemical yields were more than 50% for iodine and almost quantitative for bromine and chlorine, and the separation time were about 40 min for iodine and 90 min for the others.
The method have elucidated some interesting metabolic effects on the distribution of halogen elements in organ of rice plant that chlorine tends to be concentrated in seed, especially in grain, and bromine and iodine in leaf. The method can be combined with the previous one for Mn, Mg, K, Na, Cu, and Zn, reported in this bulletin, Vol.16, No.10, p, 526, 1967, to make a sequential activation analysis for these elements.
