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Thursday, December 11, 2008
Understanding Reversed Phase Liquid Chromatography: Using Molecular Simulation to Resolve Some of the Outstanding Questions
Mark R. Schure
Theoretical Separation Science Laboratory, Rohm and Haas Company,
727 Norristown Road, Springhouse, PA 19422-0904
Abstract:
The road to understanding the retention mechanism(s) of reversed-phase liquid chromatography (RPLC) has been controversial and speculative at best. Retention mechanisms inferred from chromatographic retention data can not be substantiated because these data are thermodynamic in nature. Molecular-based models can not be verified by thermodynamics because thermodynamics is a bookkeeping system, nothing more and nothing less. Spectroscopic investigations have been equally disappointing as the interpretation of the chain information and molecular interaction data is clouded by the diversity of signals.
In this talk we will summarize our findings about the chain configuration, retention properties and the mechanism of model RPLC systems. This will cover the chain structure, solute-chain-solvent interaction location(s), the resolution of both the solvophobic vs. lipophilic and adsorption vs. partition controversies, the effect of embedding polar groups within the bonded chains, and the consequences of varying the surface coverage.
Rather than using equations, we will illustrate a molecular-level description of the retention mechanism in RPLC with a generous amount of molecular visualization and metrics that pertain to chain location. Experimental numbers will be compared with simulation and shown to be in excellent agreement.
I am hoping to convince you with a simple, yet in depth description, that most details about the RPLC retention mechanism of non-ionizable solutes are now understood.
About the Speaker:
Mark Schure’s work in separation science includes studies of chromatography, capillary electrophoresis, multidimensional chromatography and field-flow fractionation. He is Technical Director of the Computational Chemistry Group and the Theoretical Separation Science Group in the Rohm and Haas Company. He has published over 100 papers, patents, book chapters and movies. He recently edited a book on Multidimensional Chromatography.
Schure received his BS from Northeastern University and his Ph.D. from Colorado State University in atmospheric environmental chemistry. Following two years of post-doctoral study at the University of Utah with J. C. Giddings, he joined the science group at Digital Equipment Corporation in 1984. In 1989, he moved to the Rohm and Haas Company. His interests include separation science, molecular modeling, colloidal science and solving large-scale chemical and physical problems with computers. He received the Arthur Doolittle award from the Polymeric Materials Science and Engineering (PMSE) Division of the ACS in 1991. Since 1995, Schure has been Adjunct Professor of Chemical Engineering at the University of Delaware. Schure has been chairman of many conferences on separation methods including the HPLC-series of conferences (HPLC 2004) and the ISPPP-series of conferences.
Details:
| Location: | D'ignazio's Towne House |
| Times: | 5:00 PM Executive Committee Meeting 5:45 PM Social "Hour" 6:30 PM Dinner 7:30 PM Presentation |
| Cost: | $30 |
| Dinner Choices: | Grilled chicken breast with lemon herb butter Crabcakes Eggplant |
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