Sunday, January 25th, 2015

Notices

January 4, 2015 by admin  
Filed under Meetings

1.January 12, 2015 Meeting in Columbia; Speaker: David R. Goodlett, Ph.D., University of Maryland, Baltimore; Topic: Development of Surface Acoustic Wave Nebulization as an Ion Source

January 2015 Meeting

January 4, 2015 by admin  
Filed under Meetings

Speaker: David R. Goodlett, Ph.D., University of Maryland, Baltimore

Topic: Development of Surface Acoustic Wave Nebulization as an Ion Source

Date: Monday, January 12, 2015

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: A surface acoustic wave (SAW) is an acoustic wave traveling along the surface of a material. This phenomenon has been studied extensively in the field of electronics where SAW devices are widely used as filters, oscillators and transformers1. In 2010 the first paper describing their use for producing ions for mass spectrometric detection was published, and the phrase ‘surface acoustic wave nebulization’ (SAWN) coined to describe this phenomenon2. Ions produced by SAWN are done so either in a continuous electrospray ionization (ESI) like mode or an intermittent manner like matrix-assisted laser desorption ionization (MALDI). In either mode nebulization occurs from a planar surface, with the opportunity to detect either positive- or negative-ions. Notably, SAWN mass spectra, of chemical compounds such as peptides and proteins that are chemically basic in nature, commonly exhibit a lower average charge state distribution than ESI produces from the same solution. Importantly, given that no DC voltage is applied to the liquid sample to produce ions, the SAWN nebulized ions can have lower internal energy than ESI or MALDI generated ions3. We’ll present the results of our latest efforts to develop this method and couple it to digital microfluidics for sample preparation on chip.

1. Lange, K.; Rapp, B. E.; Rapp, M., Surface acoustic wave biosensors: a review. Analytical and Bioanalytical Chemistry 2008, 391 (5), 1509-1519.
2. Heron, S. R.; Wilson, R.; Shaffer, S. A.; Goodlett, D. R.; Cooper, J. M., Surface Acoustic Wave Nebulization of Peptides As a Microfluidic Interface for Mass Spectrometry. Analytical Chemistry 2010, 82 (10), 3985-3989.
3. Huang, Y.; Yoon, S. H.; Heron, S. R.; Masselon, C. D.; Edgar, J. S.; Tureček, F.; Goodlett, D. R., Surface acoustic wave nebulization produces ions with lower internal energy than electrospray ionization. J Am Soc Mass Spectrom 2012, 23 (6), 1062-70.

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.

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