September 2008 Meeting Announcement, Delaware Valley Mass Spectrometry Discussion Group
PLEASE NOTE ROOM CHANGE: We will meet in Mendel 213.
- Topic: "New approaches for performing electrospray ionization mass spectrometry of less than ideal samples
- Speaker: Dan Fabris (University of Maryland Baltimore County)
- Date: Monday, September 8, 2008. 6:30 PM
- Time: Social Hour: 6:30 PM.
Talk: 7:30 PM.
Please RSVP to John Masucci JMASUCCI@PRDUS.JNJ.COM by Thursday September 4th.
- Place: Department of Chemistry, Villanova University (Room 213, Mendel Hall)
Commercial electrospray ionization (ESI) mass spectrometers employ a constant emitter voltage to achieve stable spray conditions, but this mode of operation has proven ill-suited for responding to spray instabilities introduced by high salt concentrations or discharge typical of negative ion mode experiments. For this reason, we have developed a feedback control that reads the actual spray current and immediately readjusts the emitter voltage in real-time. The current-controlled system allows for much improved signal stability, which translates into increased signal to noise ratio (S/N) and overall spectral intensity. High salt concentrations induce also the formation of non-specific metal adducts that distribute the available ion current over a broad range of mass over charge (m/z) channels, which can produce decreased resolution and S/N, as well as complete signal suppression. To address this issue, we have implemented a dual spray setup that enables ion/ion reactions between metal-adducted analyte and chelating agents in the rf-only hexapole of our Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. Gas-phase interactions between ions of like polarity allow for transfer of cations to the chelating agent, which induce significant reduction of metal adducts with associated improvements of the observed S/N and overall spectral quality. The talk will illustrate these approaches in the context of our ongoing investigation of the structure/function relationships in key protein-nucleic acids complexes involved in the lifecycle of HIV-1 and related retroviruses.
Dan Fabris performed his dissertation work at the University of Padua (Italy) and trained with Dr. Piero Traldi at the National Research Council in Padua, where he focused on the characterization of synthetic and natural products by mass spectrometry. He carried out post-doctoral work with Dr. Catherine Fenselau at the University of Maryland, Baltimore County (USA), developing mass spectrometry-based methodologies for the investigation of the mechanism of metal chelation in metalloproteins. He later joined the Faculty of the Department of Chemistry and Biochemistry of the University of Maryland, Baltimore County, where he is currently an Associate Professor. His present research interests involve the investigation of the structural determinants of molecular recognition between proteins and nucleic acids, using novel technologies based on high-resolution mass spectrometry.
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