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May 2002 Meeting |
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The Next Generation of Supports for HPLC |
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Date: | Tuesday, May 14, 2002 | |||||||
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Location: | Southbury
Hilton Southbury, CT. |
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Speaker: | Peter
W. Carr Professor, University of Minnesota President, ZirChrom Separations, Inc. |
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Agenda: | 5:30-6:30
PM Registration/Social Hour 6:30-7:30 PM Dinner 7:30-8:30 PM Presentation |
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Cost: | $30 ($15 Students and Emeritus) | |||||||
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Registration Deadline: |
Friday, May 10, 2002 | |||||||
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| Abstract: This presentation will focus on the utility of a family of novel, ultra
durable HPLC stationary phases based on the use of monodisperse, highly
porous zirconia as the substrate. These chromatographic phases result from
the development of 3 micron particles of zirconia of extraordinary
chemical, mechanical, and thermal stability.
Zirconia is a refractory metal oxide and is highly resistant to
dissolution (pH 1-14), does not shrink or swell in any chromatographically
interesting solvent, at any ionic strength and does not loose pore volume
or structure upon heating to 800-900°C.
We have developed a suite of different chemical modification
processes designed to tailor zirconia’s chromatographic performance to
enable reversed, normal phase and ion exchange as well as chiral liquid
chromatography. Although our
initial interests were to design a phase that could be used at extremes of
pH, especially for work with proteins, it has become clear that the
extremely high chemical stability of the substrate and coatings allow the
prolonged use of zirconia based stationary phases at very high
temperatures where most conventional bonded phases are only marginally
stable. The use of high temperature (100-200°C) in liquid chromatography
has many significant benefits: viscosities
are much lower thereby decreasing wear and tear on pumps and seals,
diffusion coefficients increase substantially allowing the use of higher
linear velocity and thus faster analyses. In addition, because temperature
can be varied substantially, as pointed out in numerous recent papers, it
now becomes an important and interesting variable for optimization of the
separation selectivity. The
unique surface chemistry of zirconia relative to silica readily enables us
to develop chromatographic selectivities, especially for highly polar
bases, which are different from those afforded by silica-based supports.
Furthermore, the surface chemistry of zirconia allows selectivity
to be “tuned” by choice of eluent buffer (phosphate, etc.) in ways not
possible on silica.
Thus far three distinctly different reversed-phase materials have been developed. The first is based on polybutadiene deposited and then cross-linked in the pores of the zirconia. It has selectivity very similar to conventional alkyl bonded phases, but it is useful at pH's up to 14 and at temperatures up to 200°C. The second reversed-phase material is a true adsorbent phase in which elemental carbon is fixed to zirconia’s surface. These special materials are also stable over a wide pH range and at high temperature. It has been known for a very long time that carbon adsorbents behave as reversed-phase materials. That is, large nonpolar species are more strongly retained than are smaller less hydrophobic moieties. Also, in accord with the operational characteristics of RPLC, the addition of an organic modifier to the aqueous eluent decreases retention. Despite a number of reports on the ability of carbonaceous solids to separate stereoisomers, the magnitude of the stereoselectivity is far from fully appreciated. We have developed a number of delicate separations such as the separation of o-, m-, p-derivatives, deuterated vs. non-deuterated benzenes, and synthetic intermediates, but we will focus our attention on the separation of diastereomers and the applications of carbon media to the measurement of enantiomeric excess. The third phase (DiamondBond C18) is based on an entirely novel concept in which the carbon phase described above is covalently modified by addition of an octadecyl chain. This phase is extraordinarily stable and has distinct selectivities differing from all other ZirChrom products and from traditional silica-based phases. |
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| Biography: Peter W. Carr received his B.S. in
Chemistry (1965) from the Polytechnic Institute of Brooklyn and a Ph.D. in
Analytical Chemistry at Pennsylvania State University (1969).
Prior to joining the faculty at the University of Georgia in 1969,
he was a post doctoral associate at Stanford University Medical School
(1968).
In 1977, Dr. Carr joined the faculty at the University of Minnesota where he became Professor of Chemistry in 1981. He has been a consultant to Leeds and Northrup, Hewlett-Packard and the 3M Company. He is currently President of ZirChrom Separations Inc. In 1986, he became an Associate Director of the Institute for Advanced Studies in Biological Process Technology at the University of Minnesota. He was the founder and first President of the Minnesota Chromatography Forum, and is a past Chairman of the Subdivision of Chromatography and Separation Science of the Analytical Chemistry Division of the American Chemical Society (1988-1989). Dr. Carr has served on the Editorial Advisory Boards of Analytical Chemistry, Talanta, Microchemical Journal, LC/GC, Journal of Chromatography, Chromatographia and Separation Science and Technology. He has received numerous awards including the Benedetti-Pichler Award from the American Microchemical Society, the Eastern Analytical Symposium, Inc. Award in Analytical Chemistry, the Stephen DalNogare Award of the Delaware Valley Chromatography, the American Chemical Society Award in Chromatography and the ISCO Award. He served as Program Chair of the Eighteenth International Symposium on Column Liquid Chromatography. Professor Carr and his associates have published over 230 papers in a variety of areas of Analytical Chemistry. Most recently, his research interests have focused on understanding the nature of solute-solvent interactions as they pertain to the prediction of retention, selectivity and optimization in chromatography and the development of chemically stable supports for high performance liquid chromatography (HPLC). |
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| Directions:
I-84 West Take Exit 16. At the bottom of the exit ramp, take a right. After you pass through 2 traffic lights, the Southbury Hilton will be on your right. I-84 East Take Exit 16. At the bottom of the exit ramp, take a right. After you pass through 1 traffic light, the Southbury Hilton will be on your right. Southbury
Hilton |
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