Sunday, December 21st, 2014

Notices

December 1, 2014 by admin  
Filed under Meetings

1.December 8, 2014 Meeting in Columbia; Speaker: Ann Knolhoff, Ph.D., FDA/CFSAN; Topic: Strategies for Non-Targeted Analyses in Complex Sample Matrices

December Meeting

December 1, 2014 by admin  
Filed under Meetings

Speaker: Dr. Ann Knolhoff, FDA, Center for Food Safety and Applied Nutrition

Topic: Strategies for Non-Targeted Analyses in Complex Sample Matrices

Date: Monday, December 8, 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:

Non-targeted screening for the analyses of small molecules has wide applicability in diverse research fields, such as food safety and metabolomics.  Despite the availability of high-resolution mass spectrometry instrumentation, non-targeted MS analyses are quite challenging, in part due to ion suppression, isobaric compounds, and changes in retention time which can complicate detection, identification, and the implementation of data analysis strategies.  Furthermore, the inherent sample complexity associated with food matrices requires high separation efficiency, with UPLC and longer separations, to ensure specificity.  Determining resulting data quality aids in developing streamlined data analysis approaches; data files can be difficult to mine for analytes of interest, particularly if the compound in question is a true unknown.  For example, to elucidate a correct molecular formula for a detected compound, the mass accuracy should be within 3 ppm and a maximum of 5% absolute isotope ratio deviation should be observed (Seven Golden Rules, Kind and Fiehn).  Therefore, an Orbitrap and a q-TOF were evaluated with various concentrations of a 48 compound standard mixture to determine the achievability of these thresholds in complex sample matrices.  This type of analysis also generated specific examples of impaired data quality, which would complicate automated data processing.  The feasibility of chemometric workflows is also being determined; parameters for successful parsing of the data will be discussed as well as factors that can influence data output.

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.

Next Page »