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Introduction to Modern Liquid Chromatography, Third Edition part 26

Introduction to Modern Liquid Chromatography, Third Edition part 26. High-performance liquid chromatography (HPLC) is today the leading technique for chemical analysis and related applications, with an ability to separate, analyze, and/or purify virtually any sample. Snyder and Kirkland's Introduction to Modern Liquid Chromatography has long represented the premier reference to HPLC. This Third Edition, with John Dolan as added coauthor, addresses important improvements in columns and equipment, as well as major advances in our understanding of HPLC separation, our ability to solve problems that were troublesome in the past, and the application of HPLC for new kinds of samples. . | 206 THE COLUMN a h Zorbax-PSM-300 Nuc eosi -7-300 Zorbax 3.5 gm Halo 2.7 gm Atlantis 3 gm Luna 3 gm Figure 5-2 Visual appearance of several silica particles for RPC magnification in b is 7x greater than in a . Vydac-214-TPS 15-20 1 SD parncle-sizedisfributionfor m st e mmeraalpapk ns fsimilnr size 5 as in the example of Figure 5.4. Computer simulations 10 suggest that a narrower particle-size distribution should result in columns with larger values of N as well as improved permeability i.e. a lower pressure drop other factors equal see also 11 12 . Columns with a narrower range in particle size are also more stable 13 . 5.2 COLUMN SUPPORTS 207 Figure 5-3 Column efficiency as a function of particle size and type. Sample naphthalene. Conditions 50 x 4.6-mm Cis columns mobile phase is 60 acetonitrile-water mobile phase 23 C. Courtesy of Advanced Materials Technology. Figure 5.4 Narrower particle-size-distribution for the superficially porous Halo packing of Figure 5.3 compared with that of a commercial totally porous packing. Courtesy of Advanced Materials Technologyi A second possible reason for the exceptional efficiency of the superficially porous column of Figure5.3 is t lie It ig lmsr- density of theseparticles l.Tg cc which is 30-c0 greater Aan hat os totahyporous partkles.A more denrepartick may pack morceffickddy as it iheease for larger particles. Figure 5.5 shows a transmission electron micrograph cross section of a superficially porous particle whose structure hasahighecdeeistysolid cocr and aporouccOell. Fisucr5.6a shows 208 THE COLUMN I 20kU X20 000 iMm 0001 16 30 SEI Figure 5-5 Cross-section of superficially porous Halo particles with 9-nm pores electron micrograph . Courtesy of Advanced Materials Technology. 0 Figure 5-6 Fast separation by means of a superficially porous column. Sample 1 acetone 2 tebuthiron 3 thiazuron 4 fluometuron 5 diuron 6 propanil 7 siduron 8 linuron 9 diflubenzuron. Conditions 50 x 4.6-mm Halo Cis column 2.7- im particles mobile