April 2005 Meeting Announcement, Delaware Valley Mass Spectrometry Discussion Group
- Topic: "New Techniques for LC/MS, GC/MS and MALDI MS"
- Speaker: Charles McEwen
- Date: Monday, April 11, 2005. 6:30 PM
- Time: Social Hour: 6:30 PM. (Pizza)
Talk: 7:30 PM.
- Place: Widener University, Webb Room
Although LC/MS precedes electrospray ionization (ESI) as a mass spec
technique, it was ESI that launched modern LC/MS. While ESI LC/MS is a
powerful method for the analysis of compositions containing high-mass
compounds, many important materials also contain low-mass compounds (>m/z
1000), many of which do not ionize well, or at all, by ESI. Thus, ESI ion
sources are supplemented by atmospheric pressure chemical ionization (APCI)
and even photoionization (PI) ion sources in order to address the lower
mass components. Even applying all of these techniques, there are still
numerous compounds that ionize poorly or not at all. These compounds, as
well as many that are ionized by the above LC/MS ionization methods, are
easily analyzed by GC/MS, but because GC/MS is a vacuum method and LC/MS is
an atmospheric pressure method, they usually require separate
instrumentation. This talk demonstrates the utility of an ion source
capable of ESI, APCI, or PI LC/MS and API-GC/MS.
In the early days of MALDI MS, it was thought that the analyte and matrix
needed to be soluble in the same solvent. Over time, this was disproved by
methods that worked quite well when the sample was applied to matrix using
a solvent in which the matrix had low solubility. More recently, a
technique was introduced in which the analyte and matrix are ground
together rather than dissolved. Examples will be shown in which the
solventless technique produces superior results to the traditional solvent
based method. In addition, a technique will be discussed which reduces the
time required to determine the best matrix composition for optimizing MALDI
conditions for a new analyte composition.
- Bio: Charles McEwen is a Research Fellow at DuPont Corporate Center for Analytical Sciences. He completed his PhD at the University of Virginia with Don Hunt.
- Directions: See Web Page at: http://science.widener.edu/svb/msdg/
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