Duke University Department of Chemistry

Charles H. Lochmüller

Professor of Chemistry Emeritus
Department Chair 1982-1987

Analytical Chemistry

Research Highlights Professor Lochmüller retired effective Aug 31, 2006 and has no active research program located at Duke

           email: charles.lochmuller@duke.edu
           phone: (919)660-1543
            other: FAX X1605

Charles H. Lochmüller
B.S. '62, Manhattan College; M. Sc. '65, Ph.D. '68, Fordham Univ.; Postdoctoral Fellow '67-'69, Purdue Univ.; Asst. Prof. '69-'74, Assoc. Prof. '74-'78; Prof. '78-, Chairman Department of Chemistry '82-'87, Dir., Center for Biochemical Engineering '91-93, Duke Univ.

Chair, Analytical Division, ACS '82-'83; Elected-Member, Committee of Revision, United States Phamocopeia [1984-88;'89-94;95-2000

Pioneer in Laboratory Robotics Award '86; ACS Award in Chromatography '87; AIC Outstanding N. Carolina Chemist Award '88; Societal Medal Eesti Keemia Selts [Estonian Chemical Society] '97;

Editor-in-Chief, Critical Reviews in Analytical Chemistry'94--; Fellow, AIC; Fellow Royal Soc. of Chemistry.

Research Interests {while active at Duke prior to 8/31/2006}

Separation Science is the name given to the discipline which attempts to unify, and to develop a sound theoretical basis for, methods which result in the local enrichment of a desired chemical class or a particular member of such a class. It therefore encompasses such seemingly diverse areas as filtration, distillation, extraction, chromatography, electrophoresis, centrifugation, etc. Of these, we are particularly interested in chromatographic methods with especial emphasis on improvement of the understanding of the physico-chemical processes which lead to separation and the entropic processes which tend to reduce the quality of the separation achieved.

There are two, complementary approaches to the improvement of the quality of chromatographic separations: 1) Mechanical-This involves the development of understanding regarding the processes which cause mixing or which have the same result as mixing in a chromatographic system. The technology of column manufacture, support materials and detector design is based on such considerations. 2) Chemical- This involves study of the nature of the molecular interactions which result in, first, retention and, second differential migration in a chromatographic system. In our program in chemically modified surfaces we are asking ''What is the microscopic nature of a bonded stationary phase? How much do covalently immobilized molecules behave like their free solution counterpart?''. These are the kinds of questions answered in basic Separation Science research. Their answers can have important, practical significance. For example, both ''capillary'' gas chromatography and high performance liquid chromatography are products of a combination of mechanical and chemical separations research.

In our recent research, we have used a variety of spectroscopic techniques to gain understanding of the texture, solvation and dynamics of molecules covalently-attached to surfaces. Such materials function as sorbents for solid-phase extraction, high- performance liquid chromatography and as pseudo-homogeneous catalysis catalysts. Our emphasis is always on the chemistry of these materials. Nevertheless, we pioneered the use of photothermal methods to study solvation and acid-base behavior of these and the use of steady-state and of time-dependent luminescence spectrometry to study the dynamics and organization of these materials. The extension of our experience in spectroscopy in highly-scattering systems has been to study proteins and macromolecules adsorbed to chemically-modified silicas. Using native- and probe- luminescence, we were the first to report reversible, interconversion of state of adsorbed proteins, the effect of surface modifier on the environment seen by sorbed proteins and the dynamics off structural change in the active site of an enzyme upon adsorption. Work in this area continues and we are studying the activity of and the degree of retention of the native conformation of sorbed enzymes.

We pioneered the use of Factor Analytical methods in the prediction of RPLC retention and continue to advance in that area. The goal of this chemometric exercise is to develop a better, more fundamental understanding of this complex chemical process. The practical goal is to help users of HPLC develop or transfer methods for practical analysis. We have extended the chemometric applications into the area of low -resolution spectrometry and into the behavior of polymer solutes in RPLC. The area of polymer separations based on chemical nature and not size-alone discrimination is a very challenging one. In this area we work with both organic and geo-polymers with collaborators in two European universities.

We have had a long and fruitful collaboration with scientists in Finland and Estonia related to chemometrics and modeling of complex chemical systems including polymer pyrolysis and ignition. This work complements our work in predictive models for HPLC retention and in the use of low resolution spectroscopy for compound identification via chemometric methods.