Application of New HPLC Column Technology - Comparison with Theoretical Promise
Dr. Naijun Wu
Merck & Co., Inc.
Abstract
Over the course of the past decade, several new HPLC column technologies have been developed for fast and efficient separation, which include non-porous particles, monolithic phases, sub-2 mm porous packings, and more recently fused-core particles. High-speed HPLC using these innovative technologies can produce much narrower peaks than conventional HPLC. Thus, band-broadening due to extra-column effects becomes more significant in fast separation, which results in lower column efficiency than theoretically predicted. In this presentation, theoretical and practical aspects including retention, back-pressure, column efficiency, and sample capacity are compared for these column technologies. The effect of column internal diameter, frictional heating, retention factor, and extra-column volume on efficiency for fast separation is discussed. Practical approaches to fully realizing high column efficiency in fast HPLC are described. Applications of fast separations in pharmaceutical process development are demonstrated.
Bio.
Dr. Naijun Wu received his Ph.D. degree in Analytical Chemistry from Brigham Young University, Utah, under the direction of Professor Milton Lee, where he conducted pioneering research on Ultra-high Pressure Liquid Chromatography (UHPLC) and fast Supercritical Fluid Chromatography (SFC). Since then, he has been working in Analytical Research and Development at Merck & Co., Inc., Rahway, New Jersey. As a group leader, his major responsibilities include managing analytical aspects of projects at various stages of drug process development, developing and validating analytical methods, and authoring analytical related CMC documents for filings to drug authorities. He is also leading a Fast Analytical Technology Team to develop various fast analytical methods in support of drug development.
He has authored and co-authored 45 scientific papers and given 30 presentations at National and International Conferences. He has also authored three invited reviews and contributed one book chapter. His research has focused on fast LC separation using elevated pressures and novel column technologies. His other research interests include fast LC screening, fast GC, chiral SFC, and thermodynamics in HPLC.
The Role of Particle Size Accuracy and Distribution on Column Efficiency and Back Pressure
Rick Lake
Restek
Abstract
Considerable attention has recently been paid to improving chromatographic efficiency by using smaller particle size packings for liquid chromatography. While decreasing particle size does increase efficiency (N) and provide faster analysis times, it does so at the cost of increased column back pressure. Another variable that can affect both efficiency and back pressure, which is often overlooked, is the distribution of the silica particle sizes used to pack the chromatographic column. While it is customary to report mean particle size, most manufacturers do not necessarily report the distribution around this mean. This distribution may affect the manner in which the particles orient as the bed is formed during the packing process, and thus cause changes in both efficiency and column back pressure. This presentation will demonstrate the chromatographic impact of mean particle size and particle size distribution on theoretical plates, analysis time, flow rates, and column back pressure. Several different columns will be discussed which have mean particle size diameters ranging from 1.5 to 5 microns. The limits of using smaller particles, and/or longer columns, to achieve greater efficiencies will be explored and discussed in terms of back pressure and the number of theoretical plates as a function of time. The trends shown will help in determining the optimum column configuration, given the practical limitations of the current HPLC and UHPLC instrumentation. Also, this presentation will demonstrate the chromatographic impact of particle size distribution. Several different columns will be discussed which only vary in terms of the distribution around the same mean particle size. Differences in performance will be summarized so that we are better able to predict the practical relationship between particle size distribution and chromatographic performance.
Bio.
Richard Lake is the Pharmaceutical Market Development Manager responsible for overseeing the development and application of chromatographic products for use in the pharmaceutical industry. Prior to this, he worked as a Pharmaceutical Innovations Chemist performing both GC and HPLC pharmaceutical applications, developing and presenting technical material and assisting in new product development. Before joining Restek in 2005, he worked as a study director and principal investigator for a contract research laboratory conducting various pharmaceutical studies, primarily involved in GC and LC method development and validation. During this time, he also managed the stability testing department. Prior to his career in pharmaceutical analysis, he worked as an analytical specialist working on pesticide residue and volatile/semi volatile environmental analyses.
