Monday, November 24th, 2014

Notices

November 2, 2014 by admin  
Filed under Meetings

1.November 10, 2014 Meeting in Columbia; Speaker: Alfred Yergey, Ph.D., NIH; Topic: Collision Cross Sections Using the 6560 IMS-QTOF: Confirming Some Old and Finding Some New

November Meeting

November 1, 2014 by admin  
Filed under Meetings

Speaker: Alfred Yergey, Ph.D., NIH

Topic: Collision Cross Sections Using the 6560 IMS-QTOF: Confirming Some Old and Finding Some New

Date: Monday, November 10, 2014

Time: 6:15 pm: Dinner and Social Hour; 7:15 pm: Presentation

Location: Shimadzu Scientific Instrument, Inc. Training Center 7100 Riverwood Drive, Columbia, MD 21046 (Directions)

Dinner and Social Hour Please RSVP to Asher Newsome (graham.newsome.ctr@nrl.navy.mil) if you will be attending dinner.

Abstract: Drift tube ion mobility mass spectrometry (DTIMS) is a powerful tool for both its rapid analytical separation capability and its ability to provide information about gas phase ion structures. While the gas-phase separation capability is valuable for the resolution of isobaric compounds that might be expected to have different structures, the ability to provide fundamental information about gas phase ion structures is also an important aspect of this approach. Structure determinations are achieved through the calculation of collision cross sections (CCS) based solely on the behavior of a Maxwellian energy distribution of a gas-phase ion at a given pressure and temperature and should therefore be invariant between various configurations of DTIMS instruments. We have confirmed CCS values using the Agilent 6560 Ion Mobility Q-TOF instrument operated at 4 torr N2 for a number of simple ions that have been previously published for instruments operated at atmospheric pressure. We have begun exploring CCS measurements for conformers of α-, β- and γ-cyclodextrins in both positive and negative ion modes. Additionally, we are studying the gas-phase populations present in complexes between β-cyclodextrins and cholesterol.

October 15 (Wednesday) Meeting

October 2, 2014 by admin  
Filed under Meetings

Speaker: Professor Gary L. Glish, University of North Carolina-Chapel Hill

Topic: The New Tandem MS: Ion Mobility Spectrometry/Mass Spectrometry

Date: Wednesday, October 15, 2014

Time: 6:15 pm: Dinner and Social Hour; 7:15 pm: Presentation

Location: Shimadzu Scientific Instrument, Inc. Training Center 7100 Riverwood Drive, Columbia, MD 21046 (Directions)

Dinner and Social Hour Please RSVP to Asher Newsome (graham.newsome.ctr@nrl.navy.mil) if you will be attending dinner.

Abstract:

Tandem mass spectrometry (MS/MS) is one of the most powerful methods available to the modern analytical chemist. However, as instruments become more and more sensitive there is an increasing challenge of isomeric and isobaric ions interfering with the analysis. The conventional approach to overcoming this problem is to use chromatography to separate analytes prior to ionization. While LC is a powerful analytical technique in its own right, it has some limitations when combined with mass spectrometry. A couple of important limitations are that the time frame of a chromatography separation is much slower than mass spectrometry (minutes to hours vs. seconds or less), and the order of analyte analysis cannot be adjusted in real‐time. Perhaps more importantly, for some real‐time analyses chromatography is not even an option.
As an alternative to chromatographic separations, we are developing differential ion mobility spectrometry (DIMS) as a separation method prior to mass spectrometry. While mass spectrometry separates ions based on their mass‐to‐charge ratio, conventional drift tube ion mobility spectrometry (DTIMS) is based on the ions’ shape‐to‐charge ratio. For DIMS the separation mechanism is not totally understood and while shape‐to‐charge plays a role, other factors such as the ion interaction with the drift gas are important. This makes DIMS more orthogonal to MS than DTIMS. DIMS has other differences compared to DTIMS that make DIMS more useful as an alternative to chromatography when combined with MS. In this presentation the fundamentals of DIMS will be discussed. Examples will be shown using DIMS/MS/MS to analyze isobaric peptides, aerosols in real‐time, and targeted compounds in complex matrices.

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