FUNDAMENTALS OF AMBIENT METASTABLE-INDUCED CHEMICAL IONIZATION MASS SPECTROMETRY AND ATMOSPHERIC PRESSURE ION MOBILITY SPECTROMETRY A Dissertation Presented to The Academic Faculty by Glenn A. Harris In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the School of Chemistry & Biochemistry Georgia Institute of Technology August 2011 FUNDAMENTALS OF AMBIENT METASTABLE-INDUCED CHEMICAL IONIZATION MASS SPECTROMETRY AND ATMOSPHERIC PRESSURE ION MOBILITY SPECTROMETRY Approved by: Dr. Facundo M. Fernández, Advisor Dr. M. Cameron Sullards School of Chemistry & Biochemistry School of Chemistry & Biochemistry Georgia Institute of Technology Georgia Institute of Technology Dr. Thomas M. Orlando Dr. Greg Huey School of Chemistry & Biochemistry School of Earth and Atmospheric Georgia Institute of Technology Sciences Georgia Institute of Technology Dr. Lawrence Bottomley School of Chemistry & Biochemistry Georgia Institute of Technology Date Approved: May 26th, 2011 Harris, G. A. ii I’m smart enough to know that I’m dumb. — Richard Feynman This is dedicated to… my parents, Martin and Mary Ann Harris, for advice beyond description, teaching me how to work hard and reminding me to enjoy the ride, my brother, Craig M. Harris, for being a great role model and friend, and my grandma, Mary Quattrocki, for always being supportive. To those listed above, and the rest of my family and friends, thank you for your unconditional love and support. ACKNOWLEDGEMENTS First I would like to express my gratitude to my advisor, Dr. Facundo M. Fernández, for guidance and support during the past four years. Under your supervision, my training and growth as a scientist has been outstanding. I am grateful for the financial and professional support needed to pursue the work outlined in this dissertation. I look forward to many years of friendship and collaboration. In addition, I would like to thank my committee members Dr. Thomas M. Orlando, Dr. Lawrence Bottomley, Dr. M. Cameron Sullards and Dr. Greg Huey for their advisement and interest in my graduate research. My fellow group members deserve significant thanks. Our past group members, Dr. Christina Y. Hampton, Dr. Leonard Nyadong, Dr. Arti Navare, Dr. Mark Kwasnik and Dr. Carrie Pierce set the expectations high upon my arrival. Current group members including Jose Perez, Christina Jones, Dana Hostetler, Deanna Synder, Rachel Bennett, Joel Keelor and my undergraduate researcher Caitlin E. Falcone, provided the day-to-day assistance required for the completion of my work. Also, I would like to thank Dr. Asiri S. Galhena and Dr. Manshui Zhou for their research insight as excellent post doctoral and research scientist colleagues. My collaborators and funding agencies have provided invaluable help for many of the projects I pursued. Special thanks is given to Dr. David Powell, Dr. Gary Eiceman, Dr. Jennifer Brodbelt, Dr. Douglas Henderson and Northrop Grumman, Dr. Joe Chipuk and Signature Science, Dr. Katrin Fuhrer, Dr. Marc Gonin and Dr. Richard Knochenmuss at Tofwerk AG, Dr. Michael Greene, Dr. Paul Newton, the National Science Foundation and the Department of Homeland Security. I am also grateful for the services of Sam Harris, G. A. v Mize at the College of Science machine shop as well as Richard Berdell and Jose Fonts in the School of Chemistry and Biochemistry electronics shop. I have been lucky to have many friends while studying at Georgia Tech. I must thank Michael and Sarah Stollar Smith for being a never ending source of fun, excitement and memories. Please give Betty a belly rub and a few treats for me when I leave. My roommate and friend, Nick Haase, has been a great research colleague and fellow concert and fine-dining companion while in Atlanta. I am sure Nick’s cat Sherman will enjoy life more without my constant pestering. My coffee breaks and late night adventures will never be the same without Susan Orwig. I wish you and your family my best. Other friends here in Atlanta (Jessica Peters, Lauren-Christine Orwig, Craig Clark, James Goeders, William “Chip” Humphries IV, Anthony Baldrige, Nicole Marrotta, and Meg Mackey) and old friends (Dane Lewis, Pierce Wolfinbarger, Dr. Diana Tadros, Julia Shaw, Dr. Anne Shearrow and Erica Turner) should also be thanked for their humor and support over the years. Finally and most importantly, I would like to thank my family for their unconditional love. To my parents, Martin and Mary Ann Harris, you have raised two sons better than any parents could wish for. This degree is as much yours as it is mine. Thank you for your patience, and I promise to get a real job someday. To my brother, Craig M. Harris, who would have thought that I would be the scientist in the family and you the lawyer? I look forward to your wedding later this year with M. Ashley Cain, seeing Kosmo and Clarence (the dogs) and spending many more fun weekend trips with you. Also, thank you to the rest of my family. Without you all, this task would not be possible. Harris, G. A. vi TABLE OF CONTENTS ACKNOWLEDGEMENTS………………………………………………………... v LIST OF TABLES………………………………………………………………..... xiii LIST OF FIGURES………………………………………………………………... xiv LIST OF SCHEMES………………………………………………………………. xxi LIST OF SYMBOLS……………………………………………………………..... xxii LIST OF ABBREVIATIONS……………………………………………………... xxiii SUMMARY……………………………………………………………………….... xxvi CHAPTER 1. RECENT DEVELOPMENTS WITH AMBIENT MASS SPECTROMETRY……………………………………….... 1 1.1. Abstract………………………………………………………………. ....1 1.2. Emerging Ionization Techniques: An Introduction to Ambient MS….... 1 1.3. Overview of Plasma-Based Techniques………………………………... 3 1.4. Direct Analysis In Real Time (DART)……………………………….... 5 1.4.1. Fundamentals……………………………………………….... 5 1.4.2. Instrumentation……………………………………………..... 11 1.4.3. Applications………………………………………………….. 14 1.5. Conclusion……………………………………………………………... 25 CHAPTER 2. Simulations and Experimental Investigation of Atmospheric Transport In an Ambient Metastable-Induced Chemical Ionization Source………………………………………………………………….. 26 2.1. Abstract………………………………………………………………... 26 2.2. An Introduction to Direct Analysis In Real Time………………….…. 26 2.2.1. Physicochemical Properties of DART…………………….... 26 Harris, G. A. vii 2.3. Experimental…………………………………………………………... 28 2.3.1. Instrumentation…………………………………………….... 28 2.3.2. Computer Simulations……………………………………..... 30 2.3.3. Procedure……………………………………………………. 31 2.4. Finite Element Analysis of the Ionization Source…………………….. 32 2.5. Combined Fluid-Thermal Dynamic and Electrostatic Simulations With Experimental Validation of the Spatial Variations Within The DART Ionization Region…………………………………………. 34 2.6. The Role of Sample Geometry In Space On the Observed Experimental Sensitivities With DART……………………………….. 45 2.7. Conclusion……………………………………………………………... 49 CHAPTER 3. Comparison of the Internal Energy Deposition of Direct Analysis In Real Time and Electrospray Ionization Time-of-Flight Mass Spectrometry………………………………………………………………... 50 3.1. Abstract………………………………………………………………... 50 3.2. Internal Energy Deposition……………………………………………. 50 3.2.1. Internal Energy Deposition During Ionization………………. 50 3.3. Experimental Determination of the Internal Energy Deposition…….... 52 3.3.1. Synthesis and Preparation of Para-Substituted Benzylpyridinium Salts……………………………………... 52 3.3.2. DART-MS Sampling, Instrumentation and Data Acquisition…………………………………………………... 53 3.3.3. ESI-MS Experiments, Instrumentation and Data Acquisition…………………………………………………... 55 3.3.4. Survival Yield Method and Data Analysis………………...... 56 3.3.5. Computational Fluid Dynamic Simulations……………….... 58 3.4. Determination of the Internal Energy Deposition of DART Harris, G. A. viii Compared to ESI…………………………………………………….... 59 3.5. Thermal Activation Pathways of Internal Energy Deposition………... 62 3.6. Collisional Activation Effects of Internal Energy Deposition………... 67 3.7. Influence of Fluid Dynamics on Internal Energy Deposition……….... 68 3.8. Metastable-Stimulated Desorption Effects on Internal Energy Deposition……………………………………………………………... 69 3.9. Conclusion…………………………………………………………….. 70 CHAPTER 4. Ion Yield “Hot Spots” and Suppression Effects In Direct Analysis In Real Time Mass Spectrometry of Nerve Agent Simulants……….. 71 4.1. Abstract………………………………………………………………... 71 4.2. Physicochemical Effects In the DART Ionization Region……………. 72 4.3. Experimental Set-Up of Continuous DART Sampling……………….. 73 4.3.1. Chemicals and Gases………………………………………... 73 4.3.2. DART-MS Instrumentation…………………………………. 73 4.3.3. DART-MS of Continuous Liquid Samples…………………. 74 4.4. Sampling Region Temperature Gradients…………………………….. 76 4.5. Spatial Sensitivity and Dynamic Range………………………………. 79 4.6. Ion Suppression……………………………………………………….. 84 4.7. Conclusion…………………………………………………………….. 92 CHAPTER 5. Direct Analysis In Real Time Coupled To Multiplexed Drift Tube Ion Mobility Spectrometry……………………………………………….... 94 5.1. Abstract………………………………………………………………... 94 5.2. Chemical Detection Systems………………………………………….. 94 5.2.1. Recent Developments With Chemical Detection Platforms... 94 5.2.2. Ionization Techniques Used With Drift Tube Ion Mobility Harris, G. A. ix Spectrometry……………………………………………….... 95 5.3. Experimental Development of the DART-DTIMS Platform………….. 96 5.3.1. Drift Tube Ion Mobility Spectrometer and DART Instrumentation Setup………………………………………... 96 5.3.2. DART-IMS Sample Analysis………………………………... 98 5.3.3. Determination of Reduced Mobility Terms………………….. 100 5.4. Initial Assessment of DART-DTIMS Platform………………………... 101 5.5. Probability of Detection of Toxic Industrial Chemicals……………….