Deveopment of PIXE for Small Biological Samples and Its Application to Study for Mechanism of Accumulation of Trace Elements

用PIXE制作微量生物材料的照射靶，离不开一层薄的支撑膜。本文介绍了一种制备高质量支撑膜的简便方法。制得的PVF膜厚度为0.1 mm，均一性好。连续X射线摄谱的本底为常规10 mm Maylar片的1/20。计算了理论探测下限，并用回旋加速器上的3 MeV质子对多种元素的探测下限进行了观测。(参考文献1，2，4)将PVF膜应用于200mug生物材料的支撑膜。通过对生物标准物质的分析，评价了用PVF膜进行PIXE分析的可靠性。用光电子能谱(PVF)对卤虫等小型甲壳动物的元素丰度进行了调查，研究了卤虫在人工海水中繁殖的元素丰度与大小和繁殖天数的关系。(参考文献3)硅藻，如褐藻。用PIXE对小型褐藻的元素丰度进行了测定，用PIXE多元素分析观察了微量元素，特别是锌的积累行为。目前有多种无机元素的分析方法，但大多不适用于生物材料的SUTU分析。生物和环境科学通常要求同时测定液体和凝胶样品中的微量元素。然而，传统的分析方法需要对样品进行冷冻干燥、湿法消化等前处理，而立式空气中PIXE由于不需要前处理而成为现场分析的有力工具。我们计划安装一种新的立式空气中PIXE，并讨论了多种元素在液体和薄膜靶中的检测下限。(参考文献5)

A thin support film is indispensable to make irradiation targets of a small amount of biological material for trace anlyasis by PIXE.We developed a simple technique for the preparation of high quality support film. The thickness of this polyvinylformarl (PVF) film was 0.1 mm with good homogeneity. The continuous X-ray making background of spectrum was <1/20 that of conventional 10mm Maylar film. We calculated theoretical detection limits and also observed <1ng detection limits for many kinds of elements by 3MeV protons from a cyclotron. (Reference 1,2,4) The PVF film was applied for the support film for <200mug of biological materials. The reliability of the PIXE analysis using the PVF film was evaluated by analysis for biological standart materials. The elemental abundance in the small Crustacea such as Artemia salina was surveyed by the PVF PIXE.artemia salina was bred in artificial sea water and the characteristic of elemental abundance as a function of size and breeding day was described. (Reference 3) Diatom such as Pheodictylum sp. from Pacific Ocean was also bred in artificial sea water and the elemental abundance in the small Pheodictylum sp.was surveyed by PIXE.Accumulation behavior of trace elements especially for zinc was observed by multielemental analysis by PIXE.Many kinds of analytical methods for determination of inorganic elements are available, however, most of them are not suitable for in sutu analysis of biological materials. Biological and environmental science ofter require simultaneous determination of trace elements inliquid and gel samples. However, conventional analytical methodns require pretreatment of samples such as freeze drying, wet digestion, etc. By constant, vertical type in-air PIXE is powerful tool for in situ analysis because of no pretreatment. We have planned to install a new vertical type in-air PIXE and discussed the detection limits for many kinds of elements in liquid and thin film target. (Reference 5)