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

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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)