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Our Restek presenters have been chosen from across our organization for their in-depth knowledge, extensive experience, and innate ability to present complex material clearly and effectively. You will also find many of our presenters on ChromaBLOGraphy at

Scott Adams

Equipped with a BS from The Pennsylvania State University and two years' experience as an environmental chemist at Lancaster Labs, Scott spent 13 years with Alltech Associates/WR Grace, where he worked in research & development, technical support, applications, product management, and e-business. Most recently before joining Restek, he also worked at Thermo Scientific as an applications specialist. Currently, Scott is Restek's GC business manager.



Mark Badger

Dr. Mark Badger, Restek’s GC Accessories product manager, has been with Restek Corporation since 2002. He has had several roles within the organization: R&D, new product development and technical support, domestic and international sales. An analytical chemist by training, his academic career was focused on applied hydrocarbon process technology. After obtaining his PhD from Staffordshire University, UK, Mark worked for the Energy Institute at The Pennsylvania State University for six years.


Paul Connolly

Paul brought 24 years of analytical and chromatography expertise to Restek, including 16 years performing LC-MS/MS. He earned his BS in biology and a minor in chemistry from the University of Pittsburgh, after which he was an environmental GC, GC-MS, and HPLC chemist for nearly a decade. Paul has also worked as a scientist and was principle investigator, group leader, technical leader, and method developer for a contract research organization providing LC-MS/MS support to the food safety, environmental, animal health, and crop protection industries. Paul was also a bioanalytical laboratory director, providing analytical laboratory services for drug development. As our liquid chromatography business manager, Paul's main focus is to grow and develop Restek's LC product lines and to provide our customers with high-performing solutions to their LC challenges.


Jaap de Zeeuw

Jaap is a world-renowned chromatographer with over 40 years of experience, including 15 years with Restek and 27 years with Varian/Chrompack prior to joining Restek. Throughout his career, Jaap has focused the chromatographic challenges of industrial analysis. For his 1979 graduation from The Institute for Higher Education, where he specialized in chemistry, Jaap authored a paper titled "The Challenge of Coating Flexible Fused Silica Capillary Columns" and has since distinguished himself as an authority on the subject. Jaap has been directly involved with the creation of numerous chemically bonded columns, including the first bonded PEG column and the stabilized PLOT columns widely used in the petrochemical arena. He has also helped develop new techniques, such as fast GC-MS using vacuum GC technology (low-pressure GC or LPGC). Over his innovative career, he has filed several patents for his work. Based out of the Netherlands, Jaap is extensively published and regularly travels internationally to share his knowledge. After retiring from Restek, Jaap founded CreaVisions, where he works as a GC Consultant and teaches master classes on key GC topics as well as on creativity in science.


Chris English

Since 2004, Chris has managed a team of chemists in Restek's innovations laboratory who perform new product testing, method development, and applications work. Before taking the reins of our lab, he spent seven years as an environmental chemist and was critical to the development of Restek’s current line of volatile GC columns. Prior to joining Restek, he operated a variety of gas chromatographic detectors conducting method development and sample analysis. Chris holds a BS in environmental science from Saint Michael's College.

Jason Fisher

Jason Fisher is the Reference Standards Product Manager for Restek. Jason has been with the company since 2006 and has supervised the packed column, inlet liner, LC columns, and air canister operations. Additionally, he managed the reference standards production and formulation chemistry teams prior to transitioning into product management in 2011.



Jana Hepner

Jana is an application scientist in Restek’s innovations lab. Her primary research focus is the development of solutions in food analysis for GC-MS and GC-MS/MS. Jana has over 10 years of experience with method development in both gas and liquid chromatography. Prior to joining Restek, she received her PhD in analytical chemistry from the University of North Dakota and her MS degree from the University of Chemical Technology, Prague.


Jason S. Herrington, PhD

Jason joined Restek in 2011 after spending over 10 years in environmental analysis, most notably as a postdoctoral research fellow with the U.S. EPA focusing on the development of techniques for organic speciation of ambient gas-phase and particulate air toxics. He has a BS in environmental sciences from Rutgers University and a PhD in exposure science from The University of Medicine and Dentistry of New Jersey. His wide-ranging work has been published in over a dozen peer-reviewed manuscripts and presented around the world. As a senior scientist with Restek, Jason is heavily involved with developing new air products and applications.


Ty Kahler

Ty joined Restek as a senior innovations chemist in 2008 and has since become the senior manager of the LC Solutions Group, which includes all aspects of R&D and applications as well as LC-related sample preparation. In addition to overseeing the LC lab, his responsibilities include LC methods development; quality implementation and investigation, and phase design/research. Prior to joining Restek, Ty worked as a manager, study director, and principal investigator for a contract research laboratory and pharmaceutical company conducting methods development, validation, and routine analysis of pharmaceuticals and agrochemicals. He has been in the field of liquid chromatography for almost 20 years, including time as a quality control chemist and instrumentation metrologist.

Jonathan Keim

Jonathan "Munch" Keim found his initial home at Restek in technical service, where he spent eight years putting his BS in chemistry from Juniata College and MS in analytical chemistry from the University of Pittsburgh to work assisting Restek's customers. He started as a technical service specialist and ultimately rose to technical service manager before assuming the role of sample preparation product marketing manager. Since 2012, Jonathan has been supporting and expanding the company’s technical training program as education program manager. Along with providing instruction on QuEChERS and other sample prep methods, Jonathan also lends his expertise to our GC and GC-MS seminars.


Joe Konschnik

In his role as Restek’s business development manager for the global food and agriculture market, Joe applies his 36 years of analytical chemistry experience toward observing market needs, overseeing technical content development for new applications, and identifying new technologies and product opportunities. After receiving his BS in public/environmental health, Joe spent the next 19 years of his career working for some of the nation’s largest environmental testing laboratory companies. As an analytical chemist, he performed methods for analysis of organic and inorganic contaminants in water, soil, and air matrices and gained experience in sample collection, preparation, and analysis. Joe has been an employee-owner with Restek for nearly 18 years and has been an invited speaker on sampling and analytical chemistry topics globally. Joe serves in volunteer leadership roles for several industry-related organizations: he is board chair of the Independent Laboratories Institute (ILI); an executive committee member of the food sciences section of the American Council of Independent Labs (ACIL); and past chair of the sampling and laboratory analysis committee (SLAC) of the American Industrial Hygiene Association (AIHA). Joe is also an active member of AOAC International, NACRW, and AOCS.


Shun-Hsin Liang

Shun-Hsin is a senior LC applications scientist at Restek. He received his bachelor’s degree from the National Taiwan University in 1988 and obtained his PhD from Michigan State University in 1996. He performed postdoctoral research at the University of Michigan from 1996 to 2000 for oncology studies. In 2001, he was appointed as research faculty at The Pennsylvania State University and focused on molecular toxicology research. In 2006, he joined MPI Research Inc. as a senior research scientist and was a study director for GLP analytical projects. In 2013, Dr. Liang joined the LC Solutions department at Restek and specialized in developing application methods across the fields of environmental, food safety, and life sciences.



Dörte Lohrberg, PhD

Dörte started her career at Restek as a sales rep in 2012, consulting and visiting customers for six years​. In 2019, Dörte began working as a specialist for reference standards, providing her expertise about reference standards and compliance to customer and colleagues. Since 2022, Dörte has assumed the role of the business development manager for reference standards with a renewed focus on identifying and building new business opportunities for Restek's reference standards within the food, environmental, and cannabis market. Prior to joining Restek, Dörte worked at the Federal Institute for Material Research and Testing and was a research associate at the Leibniz Institute for Molecular Pharmacology in Berlin. She has a diploma degree in agricultural engineering and holds a PhD in protein biochemistry.



Sharon Lupo

Sharon Lupo joined Restek in 2010 as an LC applications chemist. While in this position, she focused on developing LC-MS/MS applications and providing LC technical support for the environmental, food safety, and clinical markets. Currently, Sharon is a senior scientist for the LC product development group and uses her market knowledge and analytical skills to develop new and innovative LC products. Sharon has over 20 years of experience in the field of liquid chromatography. Prior to joining Restek, she was a principal investigator, study director, and analytical chemist for GLP- and GMP-regulated environmental, bioanalytical, and pharmaceutical studies.


Colton Myers

Colton Myers is a GC applications scientist at Restek Corporation where he is developing GC workflow solutions for the cannabis industry. In addition to his applications responsibilities, he also researches solid-phase microextraction (SPME) and assists in the development of new GC column stationary phases. Colton received his BS in chemistry from Juniata College in the U. S., and his notable accomplishments include contributions to published manuscripts in the Journal of Chromatography A on the analysis of electronic cigarettes and in Separations on a review of the SPME Arrow.


Jan Pijpelink

Jan is a 39-year veteran of the petrochemical industry with extensive international experience in petro laboratories and with process applications throughout North America, Europe, and Asia. In his current position of technical business development manager for energy and chemicals, Jan leads our scientific collaborations and key industry partnerships. Jan also serves as chair of ASTM Section D02.D0.03 (C3 hydrocarbons), and as vice chair of D02.04.0H (SimDist).

Chris Rattray

Chris is a senior scientist in GC Solutions with a BS in chemistry from the University of California, Riverside, and almost 15 years’ experience in environmental analysis. Prior to joining Restek, Chris worked at multiple environmental testing laboratories in Southern California in the positions of organic analyst, organic supervisor, technical director, and laboratory director. Chris’s responsibilities at Restek are split between the optimization of existing environmental methods and the development of new GC columns and GC accessories.


Nathaly Reyes-Garcés, PhD

Nathaly Reyes-Garcés is an application scientist at Restek Corporation in the LC solutions department where she works on the development of analytical workflows relevant to the cannabis market. Nathaly holds a BS in chemistry from the Industrial University of Santander (Colombia) and earned her MS and a PhD in chemistry at the University of Waterloo (Canada). During her MS studies, she worked on the application of microextraction techniques for environmental analysis using gas chromatography coupled to different detectors. Her doctoral work was focused on the application of SPME in combination with liquid chromatography and mass spectrometry (LC-MS) for the analysis of various drugs and metabolites in biological samples and in vivo systems. From 2017 to 2018, Nathaly was appointed as a postdoctoral fellow at the University of Waterloo where she continued to use SPME in different formats and LC-MS for various applications. Nathaly has coauthored more than 20 publications in analytical chemistry journals and has presented her work in different local and international scientific meetings.

Randy Romesberg

Randy is a senior scientist who has been immersed in the design, manufacture, and use of LC columns for over 30 years. After working at Keystone Scientific, Inc., as both a chemist and research/applications supervisor, he came to Restek in 1994 to help establish Restek’s LC column product line. Ever since, he has been developing a steady stream of innovative new stationary phases, silica particles, and column hardware, such as the Biphenyl stationary phase, Pinnacle II silica and Trident guard system. Randy holds a BS in science from Penn State University and has collaborated with other organizations such as The Ohio State University and the National Institute of Science and Technology.

Kristi Sellers

With over 30 years of experience in chromatography, Kristi has worked for Restek as an applications chemist with experience in both GC and LC method development. She has also worked as a QC chemist and a process chemist in addition to her managerial positions in GC Column manufacturing, QC, the Applied Science Group, and R&D. Kristi is currently a senior product marketing manager for GC columns. She holds a BS in chemistry from Lock Haven University, an MBA from Regis University, and has been a Restek seminar instructor for more than three decades.

Gary Stidsen

Gary has over 30 years of experience in chromatography, including sample preparation techniques, air sampling, and chromatographic analysis. He specializes in gas chromatography with an emphasis on the environmental and petroleum markets. Gary has been at Restek for almost 20 years and has played an instrumental role in developing many key products and numerous applications. During this time, he has served as the innovations lab manager, product manager for both the GC Column and air sampling lines, and director of research and innovation, where he was responsible for all aspects of research and new product development. Gary is currently our business manager overseeing reference standards, air sampling, and sample preparation.


Jason Thomas

Jason first came to "Chromatography Valley," the location of Restek's state-of-the-art manufacturing and development facility, as a student of chemistry at The Pennsylvania State University. Upon graduation, he ventured into the environmental and chemical industries for four years before finding a home at Restek, where he has been involved in GC column development, environmental applications, and most recently, SPE new product development, over the course of the last 15 years.

Melinda Urich

Melinda “Mel” Urich is an applications scientist in the LC Solutions department. Her primary focus is on the development of novel applications in the cannabis and food markets. In her previous role at Restek as an LC manufacturing chemist, she led the synthesis of silica, bonding of stationary phases as well as new process implementations and improvements. Mel attended Juniata College where she earned her BS in Chemistry and performed research in Atomic Force Microscopy (AFM).

Landon Wiest, PhD

As a scientist for LC Research and Development at Restek since 2013, Landon has focused on new product development as well as creating comprehensive workflow solutions for applications in food safety and environmental testing. Landon earned his PhD in analytical chemistry from Brigham Young University in 2013, where he developed patented LC phases on diamond-based supports. While creating new products and applications for Restek, Landon also has a passion for creating content and training materials that make workflows and chromatography more accessible. He has published in multiple peer-reviewed journals and continues to present his research at conferences and through Restek’s website in the form of blog posts, video clips, and written content.


Becky Wittrig, PhD

Becky is Restek's vice president of sales and is responsible for sales and distribution activities in this region. She has over 25 years of experience in chromatography, including GC and LC method development in the areas of food composition and food safety, environmental contaminants, and toxicology. She served previously as the European sales manager, Restek’s global LC specialist (2003–2009) and as a food & flavors applications chemist (2001–2003). Becky also spent two years as the food & environmental business development manager at AB SCIEX before rejoining Restek in 2011. Prior to moving from the Twin Cities to the Happy Valley, she supervised the chromatography laboratories at the Pillsbury Company and Ecolab, Inc., both in St. Paul, Minnesota. In addition to her BA in chemistry from Gustavus Adolphus College (St. Peter, Minnesota), Becky holds a PhD in analytical chemistry from Purdue University and an MBA from the Krannert School of Business at Purdue.

Jamie York, PhD

Jamie York is a scientist in the Applications Lab at Restek Corporation in the LC Solutions department, where she works on the development of novel applications for the food, clinical, and cannabis markets. She earned her PhD in chemistry from The University of Texas at Arlington in 2019. There, she mastered many analytical techniques including gas chromatography–vacuum ultraviolet; gas chromatography–mass spectrometry; matrix-assisted laser desorption/ionization; and liquid chromatography–mass spectrometry with a focus on food and environmental research. Jamie continued her post-doctoral work at The University of Texas at Arlington with a focus on the analysis of mammalian cell culture media by LC-MS/MS.


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