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John Bowdenjohnabowden@gmail.com
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About Me:
Graduate of University of Florida
BS in Chemistry May 2003
Joined Yost Group 2003
Ph.D. Defense, December 2008
Main Focus: Interdisciplinary project involving mass spectrometry and steroid metabolism
Areas of Interest: Mass spectrometry in life sciences, GC/MS, GC/MS/MS, LC/MS, LC/MS/MS, sample preparation techniques (SPE, SPME, LLE), microwave chemistry, metabolic profiling, endocrine disrupting compounds (EDCs), steroids
Research Collaborators: Dr. Guillette and Research Group in Zoology (UF)
Dissertation Abstract:
Ongoing research has demonstrated that specific environmental contaminants, commonly referred to as endocrine disrupting compounds (EDCs), can alter the functioning of the endocrine system by affecting normal growth, development and reproduction. In consequence, there is a fundamental need for innovative methods to improve the characterization of EDCs and their role in EDC-induced alterations in wildlife, specifically the changes in endogenous steroid profiles. The diverse physiochemical properties of steroids and EDCs impose inherent analytical limitations and thus current analytical methodologies for monitoring these compounds are often limited in scope and scale, limiting the overall understanding of contaminant-steroidogenesis interactions.
New strategies that can simultaneously analyze a wide range of endogenous steroids in one chromatographic analysis would be a significant improvement over current methods. In the research reported here, application of chromatographic techniques such as gas and liquid chromatography, coupled with mass spectrometry (GC/MS, LC/MS), are shown to offer promising profiling capabilities in increasing the number of compounds detected and quantified. Several innovative sample preparation strategies, involving extraction and derivatization, were optimized and tailored to expand the dynamic range of compounds capable of being analyzed in a single analysis. In particular, novel extraction (solid-phase extraction (SPE) with several sorbents and solid-phase microextraction (SPME) with on-fiber derivatization) and derivatization (including microwave and solvent enhancement) strategies were explored and optimized. Sample preparation techniques were evaluated and compared in terms of yield, reproducibility, and overall analysis time.
The overall profiling schemes were effective for the characterization of a diverse suite of environmental EDCs in surface water samples and steroids in alligator plasma. The analysis of endogenous steroids in the American alligator, in concert with the detection of EDCs from its natural (indigenous) water environment, provides a unique opportunity to correlate changes in the normal endocrine milieu in response to possible EDC exposure.
Awards:
Chemistry Department Teaching Award, University of Florida; 2006–07
Graduate Student Teaching Assistant Award, College of Liberal Arts and Sciences, University of Florida; 2005–06
Chemistry Department Teaching Award, University of Florida; 2003–04
Publications:
Bowden, J. A., D. M. Colosi, D. C. Mora-Montero, T. J. Garrett, R. A. Yost. Evaluation of Derivatization Strategies for the Comprehensive Analysis of Endocrine Disrupting Compounds (EDCs) using Gas Chromatography/Mass Spectrometry (GC/MS). Journal of Chromatographic Science (in press)
Colosi, D. M., J. A. Bowden, D. C. Mora-Montero, T. J. Garrett, R. A. Yost. Investigation of High-Performance Liquid Chromatography-Mass Spectrometry (HPLC/MS) using a Monolithic Column to Separate a Diverse Suite of Steroids. Journal of Chromatographic Science (in press)
Bowden, J. A., D. M. Colosi, D. C. Mora-Montero, T. J. Garrett, R. A. Yost. Chemical Derivatization Strategies for the Comprehensive Profiling of Steroids using Gas Chromatography/Mass Spectrometry (submitted for publication – Journal of Chromatography B)
Bowden, J. A., D. M. Colosi, D. C. Mora-Montero, T. J. Garrett, R. A. Yost. Enhancement of Microwave-Accelerated Derivatization (MAD) for the Multi-Class Analysis of Steroids by Gas Chromatography-Mass Spectrometry (GC-MS)(submitted for publication – Analytical Chemistry)
Bowden, J. A., D. M. Colosi, T. J. Garrett, R. A. Yost. Evaluation of a Novel Solid-Phase Microextraction On-Fiber Derivatization (SPME-OFD) Method for the Analysis of Estrogens in Alligator Plasma using Gas Chromatography/Mass Spectrometry (in preparation)
Bowden, J. A., D. M. Colosi, T. J. Garrett, R. A. Yost. Evaluation of Novel Extraction Strategies for the Analysis of Steroids and Endocrine Disrupting Compounds (EDCs) in Environmental and Biological Samples using Gas Chromatography/Mass Spectrometry (GC/MS) (in preparation)
Teaching/Mentoring Experience:
Teaching Assistant – Analytical Chemistry, University of Florida (May 2008 – August 2008)
Teaching Assistant – Instrumental Analysis Laboratory, University of Florida (January 2004 – May 2007, August 2007 – December 2008)
Teaching Assistant Trainer – Instrumental Analysis Laboratory, University of Florida (August 2005 – May 2007, August 2007 – December 2008)
Teaching Assistant – Analytical Chemistry Laboratory, University of Florida (August 2002 – December 2003)
Mentoring Experience:
Howard Hughes Medical Institute G.A.T.O.R. Mentoring Program (Biomedical Science) Group Advantaged Training of Research (G.A.T.O.R) Graduate Mentor (May 2007 – May 2008)
Diana C. Mora-Montero: Mass Spectrometric Imaging of Steroids in Alligator Tissue Using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI/MS)
Dominic M. Colosi: Development of an LC/MS Method (using both Conventional Columns and Non-Traditional Monolithic Columns) for the Comprehensive Profiling of Steroids - Presented poster at 56th ASMS Conference on Mass Spectrometry
Poster Presentations:
Evaluation of Microwave-Accelerated Derivatization (MAD) for the Comprehensive Analysis of Steroids by Gas Chromatography/Mass Spectrometry (GC/MS)
The Proceedings of the 56th ASMS Conference on Mass Spectrometry and Allied Topics;GC/MS Poster Session
June 1 – 5, 2008; Denver, CO
Evaluation of Solid-Phase Microextraction/On-Fiber Derivatization/Gas Chromatography/Mass Spectrometry for Profiling Steroids and their Metabolites in the American Alligator
The Proceedings of the 55th ASMS Conference on Mass Spectrometry and Allied Topics; GC/MS Poster Session
June 3-7, 2007, Indianapolis, Indiana
The Application of Gas Chromatography/Mass Spectrometry for the Development of a Comprehensive Steroid Profile
Moffitt Symposium on Mass Spectrometry (MS/MS)
April 12 – 13, 2007; H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL
Evaluation of Novel Mass Spectrometric Approaches for Comprehensive Steroid Profiling to Characterize the Effects of Endocrine Disrupting Chemicals in Alligators
HHMI-UF Science Fair (Howard Hughes Medical Institute - University of Florida)
February 12 – 14, 2007; Gainesville, FL
The Application of GC/MS to Quantify 17b-estradiol within the Thyroid-Gonad Signaling Pathway of the American Alligator (Alligator Mississippiensis)
The Proceedings of the 54th ASMS Conference on Mass Spectrometry and Allied Topics;
May 28 - June 1, 2006, Seattle, Washington
Quantitation of Endogenous Compounds and Natural Products Poster Session
GC/MS/MS Characterization of Steroids and their Metabolites in Alligators
The Proceedings of the 53rd ASMS Conference on Mass Spectrometry and Allied Topics;
June 5-9, 2005, San Antonio, Texas
Environmental Analysis Poster Session
Oral Presentations:
Novel Analytical Strategies for the Characterization of Steroids and Endocrine Disrupting Compounds (EDCs) in Biological and Environmental Samples
Chemistry Department, Analytical Division Research Seminar
November 19, 2008; University of Florida, Gainesville, FL
Sample Preparation Strategies for the Development of Comprehensive Steroid Profiling
using GC-MS
83rd Annual Florida Meeting and Exposition (FAME) of the American Chemical Society; Analytical Chemistry Session; May 10 – 12, 2007; Orlando, FL
Comprehensive Two-Dimensional Chromatography (GCxGC) for Complex Mixtures
Chemistry Department, Analytical Division Literature Seminar, November 8, 2006
The Application of GC/MS to Quantify 17b-estradiol within the Thyroid-Gonad Signaling Pathway of the American Alligator (Alligator Mississippiensis)
82nd Annual Florida Meeting and Exposition (FAME) of the American Chemical Society; May 11-13, 2006, Orlando, Florida
Analytical Chemistry Session