TARGET PREPARATION FOR BIOLOGICAL MATERIAL BY PASTE SPREADING METHOD FOR PIXE ANALYSIS WITH A SMALL CYCLOTRON

A paste spreading method for target preparation of biological materials for PIXE analysis by proton beams from a small cyclotron is developed. Quantitative results obtained for NIST Bovine Liver (SRM 1577b) are consistent with values certified by NIST for almost all elements heavier than Mg except for Ca and Rb. Concentrations of Cl and Br, which are volatile under acidic condition, can also be reasonably determined. Effect of wet ashing on determination of Se is examined, then recovery of Se, which means a ratio of determined value divided by that of Se added to NIST Bovine Liver, falls to less than 50% because of vaporization during drying, and especially decreases to 22% when the targets were dried by lyophilization. On the other hand, the recovery for targets prepared by the paste spreading method reaches about 100%. As an example of target preparation for a real sample material by the paste spreading method, elemental concentrations in the liver of Long-Evans Cinnamon (LEC) rats, where Cu spontaneously accumulates, and of Sprague-Dawley (SD) rats as a control are determined. Among 12 elements determined, the concentrations of hepatic S, Fe, Cu, Zn, and Se of LEC rats are significantly higher than those of SD rats (P<0.01).