Organic and Biological Mass Spectrometry Group, Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6131, USA.
Anal Chem. 2011 Jan 15;83(2):598-603. doi: 10.1021/ac102766w. Epub 2010 Dec 15.
Proximal probe thermal desorption/secondary ionization mass spectrometry was studied and applied to molecular surface sampling and chemical imaging using printed patterns on photopaper as test substrates. With the use of a circular cross section proximal probe with a tip diameter of 50 μm and fixed temperature (350 °C), the influence of probe-to-surface distance, lane scan spacing, and surface scan speed on signal quality and spatial resolution were studied and optimized. As a compromise between signal amplitude, signal reproducibility, and data acquisition time, a surface scan speed of 100 μm/s, probe-to-paper surface distance of 5 μm, and lane spacing of 10 μm were used for imaging. Under those conditions the proximal probe thermal desorption/secondary ionization mass spectrometry method was able to achieve a spatial resolution of about 50 μm as determined by the ability to distinguish surface patterns of known dimensions that were printed on the paper substrate. It is expected that spatial resolution and chemical image quality could be further improved by using probes of smaller cross section size and by incorporating a means to maintain a fixed optimal probe-to-surface distance real time, continuously adapting to the changing topography of the surface during a lane scan.
近场探针热解吸/二次离子质谱法已被研究并应用于分子表面采样和化学成像，使用光纸上的印刷图案作为测试基底。使用具有 50μm 尖端直径的圆形横截面近场探针和固定温度（350°C），研究并优化了探针到表面的距离、车道扫描间距和表面扫描速度对信号质量和空间分辨率的影响。为了在信号幅度、信号重现性和数据采集时间之间取得平衡，采用 100μm/s 的表面扫描速度、5μm 的探针到纸表面的距离和 10μm 的车道间距进行成像。在这些条件下，近场探针热解吸/二次离子质谱法能够实现约 50μm 的空间分辨率，这可以通过区分打印在纸张基底上的已知尺寸的表面图案来确定。预计通过使用更小横截面尺寸的探针并结合一种实时保持固定最佳探针到表面距离的方法，可以进一步提高空间分辨率和化学图像质量，以适应在车道扫描过程中表面形貌的变化。
