Published: June 20th, 2016
This paper presents a protocol for the visualization of gaseous streams of an ambient ionization source using schlieren photography and mass spectrometry.
This manuscript outlines how to visualize mass spectrometry ambient ionization sources using schlieren photography. In order to properly optimize the mass spectrometer, it is necessary to characterize and understand the physical principles of the source. Most commercial ambient ionization sources utilize jets of nitrogen, helium, or atmospheric air to facilitate the ionization of the analyte. As a consequence, schlieren photography can be used to visualize the gas streams by exploiting the differences in refractive index between the streams and ambient air for visualization in real time. The basic setup requires a camera, mirror, flashlight, and razor blade. When properly configured, a real time image of the source is observed by watching its reflection. This allows for insight into the mechanism of action in the source, and pathways to its optimization can be elucidated. Light is shed on an otherwise invisible situation.
Mass Spectrometry, an analytical tool available for molecular mass identification, has become one of the most powerful analytical techniques to date. Over the last decade a whole host of new ambient ionization sources have become available for mass spectrometry detection. For the data collected in this manuscript, the Direct Sample Analysis (DSA) source was utilized. Although these sources are extremely versatile, a more detailed knowledge of the physical ionization process is needed for its optimization and extension of purpose. The aim of this experiment is to gain a better understanding of the ionization process within the ambient sources through visualization of t....
1. Schlieren Photography
A schematic of the schlieren setup including the mass spectrometry ionization source can be found in Figure 1. When all schlieren components are properly aligned, gases within the test region can be seen as contrasting dark and light regions. Figure 2 illustrates how this contrast can be used to observe how the shape of the nitrogen jet flow from the mass spectrometry source changes as nozzle size decreases.
There are several considerations which must be addressed prior to attempting this protocol. In addition to the space around the mass spectrometer for the source and mirror, enough open space must be available to accommodate the distance of twice the focal point of the mirror. Furthermore, the size of the mirror is ultimately decided by the size of the source that is under study. If the mirror is too small, the source will not be fully visualized. It is important to note that some, if not all, of the source covers must be.......
|Spherical Concave Mirror
|Rebel EOS T2i
|300 mm telephoto lens
|Direct Sample Analysis (DSA) Ionization Source
|Sq 300 MS with SQ Driver Software
|small drill bit #73
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