Measurement Method Of ～(41)Ca With Accelerator Mass Spectrometry

Calcium is an important element in human body. It is known that calcium deficiency in human body is related to many diseases such as Osteoporosis, arteriosclerosis and so on. In addition, Ca2+, as a messenger, plays an important role in the normal function of cells. The man-made 41Ca (T1/2=1.0×105 a) is an ideal tracer in these studies. The high sensitivity of AMS has made it possible to determine trace amount of 41Ca.This work was supported by the National Natural Science Foundation. The goal is to develop an ideal 41Ca measurement method with HI-13 tandem AMS. The main topics of research presented in this thesis are as follows: the first is the AMS samples preparation of 41Ca. There are three kinds of samples: standard, blank and the unknown biological samples. The second is the 41Ca AMS measurement. The content of 41Ca in unknown sample can be obtained by measuring the 41Ca/40Ca ratio of the unknown and standard samples.The thesis systemically describes the apparatus of the preparation of CaH2. The sample preparation is very important. It involves the reduction of CaO at high temperature, and the generation of CaH2 from metallic Ca; the two procedures must be done in special equipments. So, lots of work have been done to design and test these equipments. Finally, the overall efficiency for Ca recovery is more than 90%, even for the mass of Ca sample as small as 2mg, or less.The 41K is the main interference in the measurement of 41Ca. By using CaH2 as ion source, the major interference from 41K can be largely reduced. 41Ca is successfully identified and finally quantified by using a multi-anode detector; in present work, the sensitivity for 41Ca measurement is 10"14.The completion of this work marked a major step forward in the applications of 41Ca in our country, especially in the field of biomedicine; 41Ca can be used as a tracer to investigate the origin of the increased Ca2+ in the cells blastula has very great significance for studying the mechanism of cancer caused by carcinogenic substances; 41Ca tracer may also make contribution in the study of the mechanism, possible prevention and treatment of acalcicosis, a disorder very popular in our country.