Marshall A T, Patak A
Department of Zoology, La Trobe University, Bundoora, Victoria, Australia.
Scanning Microsc. 1993 Jun;7(2):677-91.
Films and bulk samples of Nylon, gelatin, Makrofol, epoxy resin, aminoplastic resin and sodium acetate have been used as models of biological samples. It is shown that the use of ultrathin window (UTW) detectors in scanning transmission and scanning electron microsopes permits the quantitative analysis of light elements, yielding a total element analysis with hydrogen estimated by difference or "guesstimated". Comparison with known concentrations of concentrations obtained by chemical analysis shows that X-ray microanalysis of selections by the peak to continuum ratio model and bulk samples by the phi(pz) model gives sufficiently accurate results for biological purposes. It is also shown that sections may be analysed by the standardless ratio model. The application of UTW detectors to total element analysis by quantitative elemental imaging is demonstrated of bulk biological samples. which have been freeze-substituted, embedded in epoxy resin and surface polished. The possibility of imaging the oxygen content of frozen-hydrated bulk tissue samples which have been surface polished is also demonstrated. This may lead to the imaging of water distribution in frozen-hydrated bulk samples of biological tissues. UTW detectors are also useful for detecting mass loss in organic samples by monitoring the decrease in oxygen counts and for detecting contamination by monitoring the increase in carbon counts. It is also shown that changes in carbon counts are good indicators of folds in sections.
尼龙、明胶、聚碳酸酯薄膜、环氧树脂、氨基塑料树脂和醋酸钠的薄膜及块状样品已被用作生物样品的模型。结果表明，在扫描透射电子显微镜和扫描电子显微镜中使用超薄窗口（UTW）探测器可对轻元素进行定量分析，通过差值估计或“猜测”来估算氢元素，从而实现全元素分析。与化学分析得到的已知浓度进行比较表明，通过峰背比模型对选定区域进行X射线微分析以及通过phi(pz)模型对块状样品进行分析，对于生物学目的而言能给出足够准确的结果。还表明可以通过无标样比值模型对切片进行分析。展示了UTW探测器在对经过冷冻替代、嵌入环氧树脂并进行表面抛光的块状生物样品进行全元素分析时，通过定量元素成像的应用。还展示了对经过表面抛光的冷冻水合块状组织样品的氧含量进行成像的可能性。这可能会实现对生物组织冷冻水合块状样品中水分布的成像。UTW探测器还可用于通过监测氧计数的减少来检测有机样品中的质量损失，以及通过监测碳计数的增加来检测污染。还表明碳计数的变化是切片中褶皱的良好指标。
