Increasing evidence suggests that the physicochemical properties of inhaled nanoparticles influence the resulting toxicokinetics and toxicodynamics. This report presents a method using scanning transmission electron microscopy (STEM) to measure the Mn content throughout the primary particle size distribution of welding fume particle samples collected on filters for application in exposure and health research. Dark field images were collected to assess the primary particle size distribution and energy-dispersive X-ray and electron energy loss spectroscopy were performed for measurement of Mn composition as a function of primary particle size. A manual method incorporating imaging software was used to measure the primary particle diameter and to select an integration region for compositional analysis within primary particles throughout the size range. To explore the variation in the developed metric, the method was applied to 10 gas metal arc welding (GMAW) fume particle samples of mild steel that were collected under a variety of conditions. The range of Mn composition by particle size was -0.10 to 0.19 %/nm, where a positive estimate indicates greater relative abundance of Mn increasing with primary particle size and a negative estimate conversely indicates decreasing Mn content with size. However, the estimate was only statistically significant (p<0.05) in half of the samples (n=5), which all had a positive estimate. In the remaining samples, no significant trend was measured. Our findings indicate that the method is reproducible and that differences in the abundance of Mn by primary particle size among welding fume samples can be detected.

中文翻译：

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扫描透射电子显微镜法测定焊接烟尘中锰成分与一次粒径的关系


越来越多的证据表明，吸入纳米颗粒的物理化学性质会影响最终的毒代动力学和毒效动力学。本报告介绍了一种使用扫描透射电子显微镜 (STEM) 测量过滤器上收集的焊接烟雾颗粒样品的整个初级粒径分布中的 Mn 含量的方法，用于暴露和健康研究。收集暗场图像以评估初级粒度分布，并进行能量色散X射线和电子能量损失光谱以测量作为初级粒度函数的Mn成分。使用结合成像软件的手动方法来测量初级颗粒直径并选择积分区域以在整个尺寸范围内进行初级颗粒内的成分分析。为了探索所开发指标的变化，该方法应用于在各种条件下收集的 10 个低碳钢熔化极气体保护焊 (GMAW) 烟雾颗粒样品。按粒径划分的 Mn 组成范围为 -0.10 至 0.19 %/nm，其中正估计表明 Mn 的相对丰度随初级粒径的增加而增加，而负估计则相反表明 Mn 含量随尺寸的增加而降低。然而，该估计值仅在一半样本 (n=5) 中具有统计显着性 (p<0.05)，所有样本均具有正估计值。在其余样本中，没有测量到显着趋势。我们的研究结果表明，该方法具有重复性，并且可以检测焊接烟雾样品中按一次粒径划分的锰丰度差异。