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为满足41Ca生物示踪样品测量的需要,在北京HI-13串列加速器质谱(Accelerator Mass Spec- trometry,AMS)系统上建立了以CaF2为靶样的41Ca AMS分析方法.生物样品和41Ca标准样品经过化学分离和纯化,制备成CaF2作为靶物质,AMS测量41Ca时,离子源引出CaF3-负离子,膜剥离后的电荷态选择为7+态,加速器端电压选定为8.5MV,用充有140mbarP10气体的多阳极电离室探测41Ca.结果显示探测器可实现对41Ca与同量异位素干扰41K的分辨,粒子谱中41K的计数率很低,对41Ca不形成干扰.对制备的4个标准样品(41Ca/40Ca在1.785×10-8-1.750×10-10范围)的测量结果显示41Ca/40Ca绝对测量值与标称值之间的线性关系良好(r2=0.997),经41Ca/40Ca为1.785×10-8的标准样品归一化后,S2,S4两个标样的测量值与标称值吻合较好,但标样S3的测量值与标称值有较大偏离.估计生物样品的41Ca/40Ca本底值低于8.2×10-13.
In order to meet the need of 41Ca biomarker measurement, a 41Ca AMS method with CaF2 as a target was established on an HI-13 Tandem Accelerator Mass Spectrometer (AMS) system in Beijing.The biological samples and 41Ca standard samples After chemical separation and purification, CaF2 was prepared as a target substance. When AMS measured 41Ca, the ion source led to CaF3-negative ions, the state of charge after the membrane stripping was selected as 7+ state, the accelerator terminal voltage was selected as 8.5MV, and charged with 140mbarP10 Gas multi-anode ionization chamber to detect 41Ca. The results show that the detector can achieve the isotope 41K isotope interference and the resolution of 41K, 41K in the particle count count rate is very low, 41Ca does not interfere with the preparation of the four standards The measurement results of the sample (41Ca / 40Ca in the range of 1.785 × 10-8-1.750 × 10-10) showed a good linear relationship between the absolute measured value of 41Ca / 40Ca and the nominal value (r2 = 0.997) After the standard sample of 1.785 × 10-8 is normalized, the measured values of S2 and S4 are in good agreement with the nominal value, but the measured value of standard sample S3 deviates greatly from the nominal value. The 41Ca / 40Ca background value is less than 8.2 × 10-13.