TOXIC SPECIES IN ENVIRONMENTAL AND BIOLOGICAL SAMPLES

这项研究计划的目标是开发新的方法来研究 痕量的定量测定和形态分析(ppm到ppb) 复杂的固体或液体基质中的元素。中的元素纵断面 通过X射线获得了环境和生物样品 荧光(XRF)和在痕量水平上，通过质子诱导的X射线发射 (PIXE)。这种分析能力将得到进一步发展，特别是 注意改进样品制备技术。 这项多元素技术将用于重金属元素的形态分析 元素。这将通过进行预浓缩和 不同物种的化学分离，例如，四种砷 生物样品中常见的物种，并使用PIXE 测定元素浓度的技术。替代方法 基于化学反应的动力学控制将被探索用于 砷等元素的形态。 这项研究计划最重要的目标是扩展PIXE 包括使用质子微探头(Micro-PIXE)的能力 显微尺寸样品中元素浓度的测量。 元素分布将在目标区域100微米×100微米内确定， 通过将一束1微米乘以1微米的质子束穿过该靶区。 将采取预防措施，以尽量减少样品因以下因素的影响而退化 热损伤和辐射损伤。组织切片和单个组织的元素图 这种微型PIXE系统将获得细胞。

The objectives in this research program are to develop new methods for the quantitative determination and for the speciation of trace (ppm to ppb) elements in complex solid or liquid matrices. Elemental profiles in environmental and biological samples have been obtained by X-ray fluorescence (XRF) and at trace levels, by proton induced X-ray emission (PIXE). This analytical capability will be developed further with special attention being devoted to improving techniques of sample preparation. This multielemental technique will be used for the speciation of heavy elements. This will be accomplished by carrying out preconcentration and chemical separations of the various species, for example, the four arsenic species commonly encountered in biological samples, and employing the PIXE technique for determining the elemental concentration. Alternative methods based on the kinetic control of chemical reactions will be explored for the speciation of elements such as arsenic. The most important objective in this research program is to extend the PIXE capability to include the use of a proton microprobe (micro-PIXE) for the measurement of elemental concentrations in microscopic size samples. Elemental profiles will be determined in a target area 100 mum x 100 mum, by rastering a 1 mum x 1 mum proton beam across this target area. Precautions will be taken to minimize sample degradation by the effects of heat and radiation damage. Elemental maps of tissue slices and single cells will be obtained with this micro-PIXE system.