~(211)At的色层分离和放射性扫描色谱测量
CHROMATOGRAPHIC SEPARATION OF~(211) At AND A METHOD FOR THE MEASUREMENT OF RADIOACTIVITY IN THE AUTOMATIC CHROMATO-GRAPHY SCAN SYSTEM
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摘要: 本文报道~(211)At的色层分离及其在FJ-2109型自动扫描色谱仪上的放射性测量方法。为了使测量达到最佳化,在二维“窗图”上选择道宽和扫描速度,有一个测量条件的狭窄区域给出好的放射性计数。这种实验设计和分析方法,既简便、快速且准确,适用于β或γ放射性核素的扫描色谱测量。 还研究了在1.2m回旋加速器上用27MeVα粒子束辐照Bi靶产生的~(211)At的吸附色层。在特制的石英蒸馏器中干法蒸馏,并经硅胶柱分离纯化使~(211)At得到最佳分离。~(211)At放射性薄层色谱和纸色层表明,二甲基甲酰胺的纸色层R_f大于用氯仿-乙醇以硅胶G,硅胶H或氧化铝为固定相的R_f。游离态的~(211)At或氧化Na~(211)At能制得~(211)At-屎嘧啶标记化合物,放射性产额依赖于~(211)At浓度,反应温度和时间。Abstract: Chromatographic separation of 211At and a method for the measurement of radioactivity in Model FJ-2109 automatic chromatography scan system are reported. To optimize the measurement of radioactivity,the channel width and the scan speed are selected on two-dimensional "window diagram" and a narrow region of the measurement conditions that will give acceptable radioactivity counts is found. The method is convenient, efficient and accurate. Absorption chromatography of 211At produced by irradiating Bi target with 27 MeV helium particles using 1.2m cyclotron has been investigated. After the nuclear reaction 209Bi(α,2n)211 At, the Bi target is oxidized by oxygen at 500℃ and 211At is distilled by O2/N2(V/V=1: 1) sweeping at a temperature of 720℃ in a quartz still and 211At is adsorbed on a silica gel column. Rf of 211At shows higher value on paper chromatography with dimethyl formamide than on silica gel G, silica gel H or aluminum oxide TLC with chloroform-methanol. The synthesis of 211At-uracil indicates that it can be prepared by free 211At or by oxidizing Na211 At and the radiochemical yield depends on 211At concentration, reaction temperature and time.