Sponsor:
Symposium:
This symposium has one (1) session of invited speakers listed below. Presenters whose topics relate to this symposium are invited to contribute papers to associated session(s) of oral and poster presentations.
Sessions will illustrate new ideas, techniques and advances in chromatography related fields. Our speakers will discuss advances in electrokinetic chromatography as well as ultra high pressure LC. Our session will also cover latest technique in capillary electrophoresis for separation and identification of microbes and the advances and challenges of using small-bore column for trace analysis.
Invited Speakers:
Organizer:
Sherry Movassaghi (Triangle Chromatography Discussion Group of the NC Section-ACS and Bayer Crop Science, Research Triangle Park, NC)
When and Where:
Both invited and contributed sessions will be held in the Sheraton Imperial Hotel and Convention Center. The invited session is scheduled on Thursday, November 11, 2004. The contributed papers and posters related to this symposium will be coordinated with the invited session. Posters should be sized to fit a 4' x 8' poster board. (Sheraton Floor Plan)
Abstracts:
James W. Jorgenson "Ultra-High Pressure Liquid Chromatography "
The history of HPLC has seen a progression in the use of columns packed with particles of decreasing size. Decreasing particle size has led to smaller values of the plate height and faster optimum velocities. Due to pressure limitations of existing HPLC equipment however, this trend has translated, not into columns of increasing separation efficiency, but instead, into columns offering faster analysis times. The 400 bar pressure limit of current HPLC technology is an arbitrary limit. The use of ten to ten-fold higher pressure allows the use of columns 40 cm long, packed with 1 micron particles, delivering 250,000 theoretical plates with column void times of 3 minutes.
Hardware (pumps, valves, injectors, connecting tubing, columns) must be made which can withstand such high pressure while in contact with solvents ranging from aqueous salt solutions to polar and non-polar organic solvents. Significant amounts of heat can be generated in pumping solvents at optimum velocities through such a highly restrictive bed of particles. In a column of conventional diameter (4.6 mm), this heat will result in axial and radial temperature gradients, which will lead to excessive band spreading. Packed capillary columns can be used to reduce this difficulty. Analyte distribution coefficients are also a function of pressure. This might result in inconvenient and/or confusing changes in relative retention times of analytes as a function of operating pressure. The design and performance of a system capable of gradient elution liquid chromatography in packed capillary columns at pressures in excess of 7,000 bar (100,000 PSI) will be described. Results of the separations of small organics, peptides, and proteins using this system, and its coupling to a mass spectrometer will also be described.
Morteza G. Khaledi "Advances in Electrokinetic Chromatography: Prospects for Multidimensional Peptide Mapping and High Throughput Drug Screening"
In this presentation, two unique aspects of Electrokinetic Chromatography (EKC) will be discussed. The focus of the first part is the use of Micellar Electrokinetic Chromatography (MEKC) for peptides separations and mapping. The significant features of MEKC are the availability of a wide range of pseudo-stationary phases that provide unique selectivities for peptides and the feasibility of manipulating the composition of the pseudo-phase since it is a completely solution based technique. In addition, phase ratio in MEKC can be accurately determined as it is related to the surfactant intrinsic properties of surfactant and concentration. Retention factor in MEKC is directly related to micelle &endash; water partition coefficients, K, and the phase ratio. This provides a unique opportunity for a priori prediction of retention behavior in MEKC for solutes with known micelle &endash; water partition coefficient values. Chromatograms of mixtures could then be readily calculated after a single measurement of the elution window boundaries under a given MEKC capillary and buffer conditions.
The use of Quantitative Structure-Partitioning Relationships (QSPR) for calculation of micelle-water partition coefficient of peptides from structural descriptors will be presented. Special attention will be given to partitioning behavior of peptides in various micellar pseudo-phases. These models have been used to predict peptides maps of digests of horse heart Cytochrome C. The prospects of predicting two-dimensional peptides separation of MEKC &endash; CZE will be discussed.
In the second part the use of Liposome Electrokinetic Chromatography (LEKC) for high throughput drug screening for prediction of oral bioavailability and membrane permeability will be presented. The migration behavior in LEKC is used to determine liposome &endash; water partition coefficient that could be used as a lipophilicity scale for modeling drug interactions with cell membranes in ADME studies in drug discovery and in Quantitative Structure Activity Relationships (QSAR).
Stephen L. Morgan "Fast Gas Chromatography/Mass Spectrometry: Applications in Forensics and Polymer Analysis"
Analytical pyrolysis extends gas chromatography (GC) to enable analysis of polymers that are not volatile due to their high molecular weight. Following a fast temperature jump, thermal fragments are separated by GC and identified by mass spectrometry (MS). The resulting chromatogram (or pyrogram) consists of contributions from all structural components of the original sample and, as such, is a reproducible signature that can be used for identification or compositional analysis of the original sample. Our laboratory has used analytical pyrolysis for characterization and identification of nonvolatile or thermally unstable materials including bacteria, industrial polymers, automobile paint, fibers, and copy toners. We have recently developed a laser pyrolysis/fast GC/time-of flight (TOF)-MS system for rapid characterization of polymers.
The forensic analysis of evidential materials can greatly benefit from the use of fast GC/MS. Increasing the speed of analyses by 5x to 10x can have a tremendous impact on throughput of laboratory casework. This paper will demonstrate the use of laser pyrolysis coupled to fast GC/MS for a variety of forensic samples such as automobile paint, rubber from tires, and fibers. For each of these applications, laser pyrolysis provides a chemical fingerprint relating to both the molecular weight and structure of the sample. High spatial resolution can be obtained by coupling a microscope to the laser system to allow analysis to be focused on micron spot sizes. One concern when using fast GC methods is whether the speed of analysis compromises information obtained. In each of the examples cited, high discrimination among different samples was achieved. Further, the resulting chromatogram of pyrolysis products could possibly be used to identify other compounds mixed within the sample, such as contaminants, dyes, pigments on a fiber sample.
Disclaimer:
This is a working document and changes will be made until the program is finalized.
Updated: September 3, 2004
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