Purdue University Graduate School
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Ambient Ionization Mass Spectrometry: Advances in Monitoring Clandestine Activities, Supporting the Warfighter, and Chemical Laboratory Education Redevelopment

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posted on 2019-01-03, 21:01 authored by Patrick W. FedickPatrick W. Fedick

Ambient ionization mass spectrometry enables rapid in-situ analysis of a plethora of analytes that are relevant to the forensic and defense communities. As the arsenal of ambient ionization techniques, aimed at solving specific targeted problems, continues to expand, the adoption of these techniques into non-academic settings has been relatively slow. At times, although the technique can provide answers in a more rapid and cheaper manner, the technique does not pass all of the required legal rules for a particular analysis when dealing with forensic evidence. This can be demonstrated with the rapid detection of drugs by paper spray ionization mass spectrometry. Paper spray ionization mass spectrometry can have drugs deposited onto the paper substrate, the paper can wipe a surface for trace analytes, and there are commercial and automated ionization sources for this process. While analysis by paper spray is rapid, the Scientific Working Group for the Analysis of Seized Drugs (SWGDRUG) states that a minimum of two instrumental techniques need to be utilized. Utilizing paper substrates that have nanoparticles embedded for surface enhanced Raman spectroscopy, that can also be utilized for paper spray ionization mass spectrometry, makes ambient ionization more appealing as it completes that first legal requirement.

Other times, the slow adoption of these new ambient ionization techniques is due to specific communities not being aware of ambient ionization, and specific applications have not yet been demonstrated. Swab touch spray ionization mass spectrometry follows similar processes as paper spray ionization, as the swab acts both as the sampling substrate and the ionization source and can swab for analytes in a manner where the paper substrate may be damaged and unable to perform the ionization for analysis. This can be seen for the swabbing of organic gunshot residues and explosives, both of which current methods already use a swab for sampling but then need lengthy extraction techniques. The applicability of paper spray ionization and swab touch spray ionization for these forensic and defense analyses is only furthered by the fact that they both couple extremely well with portable mass spectrometers for analysis in the field.

There are also many fields that ambient ionization is just starting to take its place in the analytical toolbox. Two such defense fields that are just beginning to expand into ambient ionization are the analysis of pyrotechnics and microelectronics. Pyrolysis gas-chromatography mass spectrometry methods have been developed and utilized for environmental tests for pyrotechnic formulation, but they are slow and there is an abundance of cleaning steps between analyses to prevent carry over and contamination. Using paper and swabs as the collection device and ionization source for environmental analysis of these pyrotechnics allow for them to be functioned at ambient conditions at the scale at which will be utilized in the field by the Warfighter. Similarly, authenticating microelectronics by desorption electrospray ionization mass spectrometry removes the subjectivity of the current methods, while rendering the integrated circuit intact enabling future use if deemed as a genuine part. By taking slower or more subjective tests, in a field that has not utilized ambient ionization heavily in the past and adding these new capabilities to their tool chest expands the acceptance and future applications of the technique.

As acceptance and utilization of ambient ionization grows, the next generation of scientists need to have hands on training in these techniques. Through the development of new teaching laboratories that couple both the fundamentals of the technique at hand, while also examining an interesting application to better engage the students, a number of laboratory exercises have been developed. The creation of new laboratory exercise utilizing the next generation of instrumentation and analytical techniques is vital for the future and rapid application of these techniques. The work discussed herein chronicles the utilization and demonstration of ambient ionization mass spectrometry in monitoring clandestine activities, supporting the Warfighter, and redeveloping chemical laboratory education.


Degree Type

  • Doctor of Philosophy


  • Chemistry

Campus location

  • West Lafayette

Advisor/Supervisor/Committee Chair

R. Graham Cooks

Additional Committee Member 2

Hilkka I. Kenttamaa

Additional Committee Member 3

Marcy H. Towns

Additional Committee Member 4

Mary J. Wirth