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Visualization of Ambient Mass Spectrometry with the Use of Schlieren Photography

Published: June 20th, 2016



1Department of Chemistry and Biochemistry, University of Maryland, Baltimore County

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....

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1. Schlieren Photography

  1. Establishment of the Test Region
    Note: The test region exists directly in front of the mirror.
    1. Clamp a spherical concave mirror (150 mm diameter, focal length 1,500 mm) in a ring stand clamp large enough to support the mirror. Attach the ring stand clamp with the mirror to a ring stand perpendicular to the floor. The current study used a 3 foot ring stand, but any height can be used as long as it is tall enough to be able to center .......

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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.

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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.......

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The authors would like to acknowledge Caitlin Kowalewski for aiding in the editing and formatting of this publication.


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Name Company Catalog Number Comments
Flashlight EAGTAC D25A Ti or equvilent 
Spherical Concave Mirror Anchor Optics 27633
Rebel EOS T2i Canon 4462B001 or equvilent 
300 mm telephoto lens Canon 6473A003 or equvilent 
Direct Sample Analysis (DSA) Ionization Source PerkinElmer MZ300560 or equvilent 
Sq 300 MS with SQ Driver Software PerkinElmer N2910801 or equvilent 
Ring Stand Fisher Scientific 11-474-207 or equvilent 
Laser Pointer Apollo MP1200 or equvilent 
razor blade Blue Hawk 34112 or equvilent 
small drill bit #73 CML Supply 503-273 or equvilent 
Protractor Sterling  582 or equvilent 
Hose Clamp Trident 720-6000L or equvilent 

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