Đang chuẩn bị liên kết để tải về tài liệu:
Introduction to Modern Liquid Chromatography, Third Edition part 46

Introduction to Modern Liquid Chromatography, Third Edition part 46. 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. . | 406 GRADIENT ELUTION 9.1.1 Other Reasons for the Use of Gradient Elution Apart from the need for gradient elution in the case of wide-polarity-range samples like that ofFigure 9.1 there are a number of other situations that favor or require the use of gradient elution high-mole cular-weightsamples genp icsL i arath i s efficientHPLCmechod developmeni sampleiircpacation peak tailing High-moleculasicveight compounds such as peptides proteins and oligonucleotides are useally piot candidatettcr isocracitseparation because their retention can be extremele soasttiheChsocollchanges in mobile-phase composition B . For example the reeennon factor t of a 50 000-De protern cap change by 3-fold as a result of a change in the mobile phase by only 1 B. This behavior can make it extremely difficultto obtainreproducible isocraticsepeevtionthtmasromcleculeosn different leboratosreicOe even wicCmiOrirmeliiboratoryiFurthconiose die iescrvtic separationoS amkmraeif mocromolcculeo usvollgresoltsm thnvoimeCiatnelulCon of some sample comveneneslwitLiStO a nd noseparation cmd suoO slvwdition of other componcLto wîOiC SO 1001 tWal e nvosartfhai thesamplevevtrleavcs tUo column thatoe die rrlension canaroS sudocrmptee isnScanexernmaly wide isouccac 4-values fos ll llls clotnlo1nc eomoeceotsshas vvry haeevetclordfrs of meoaicodrl. With gradieni alutioci on theothce t n0 i epdpci kir o s on times farlarga molecules areceieom a peoClem wlldpesnhwg sepaoatiooc ccnbafats eifsotive and convenienc ChaptecSeC GenuricwWarviio ns teemed for osreice pftarnales escL eO whleaesmaOe up of diffeachtcpmponencs ft ira ams cac moi i i s A B and Cacsampk a compounds D E and C msample 2 cndsv forth epioal yeaod swmple wih be separatd just once s iScn a doct teparwOonsims pentimcl witO no Ourdiee method denslcpment dot eaeC nnw sample. In this way hundreds or thousands of related samples tach withaumqua comeositiolo oan ce poecested Ouvuiumvin time and m tcminimem uctt.Gsneric sepaaatiambuM CioOdi fixed ooo .