CHROMATOGRAPHIC SEPARATION OF~(211) At AND A METHOD FOR THE MEASUREMENT OF RADIOACTIVITY IN THE AUTOMATIC CHROMATO-GRAPHY SCAN SYSTEM

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.