tailieunhanh - Introduction to Modern Liquid Chromatography, Third Edition part 91

Introduction to Modern Liquid Chromatography, Third Edition part 91. 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. . | 856 TROUBLESHOOTING Figure 17 22 Separation of tipredane epimers. Conditions a b 100 x Hypersil ODS column 29 32 62 acetonitrile buffer in 0 10 20 min mL min 26 C. c 150 x Resolve Cis column and similar but not identical gradient conditions a Injection of S-epimer injection of R-epimer c injection of S-epimer. Adapted from 31 32 slow the samphommndegi-a dev bletl esiin plHtranbts through the column resiting in a distorted peak Ce result oftwo tcr more Csslinctmoleculasstructutos eaosing through the eoSomn witCthe rotie si sheir concenttationschangotg diRmg ths separation 30 31 . An example of both fast and slow sample reactions is provided in Figure 31 32 fos w i itnlc isgrctlon ic f SwotiptedgnerpimeciistructustshownintCi figure undor difSescnt conditio nt. dt dieuse rgcprseS-epimetwaeinjettedi and peaksfosbdththelStcod 0-ehimets oee observed tn-ht Jieosou e tam reaction ofl-cpimer toR . Because the two peaks are sharp and well-separated the reaction of R toOmuit haveosxoered Ossor so eiggificantelutionthrough die column. Ttt iIl ecsionofthe ouoe Rts-imer Kg. 17h i shews a 1 1 Ort reduced contetpido go rhs ahema-e twtseparatigns ot and Fig. wess eash cdticd ooh sna p-dtil ODScotonn. Whsrthe column wa-t ds sd toReides Cp8 thetepetgtion oi oninjectidnofOie ouse S-epimer mFlt-ee wgs gsso t dnst e h t c sd it it observed ettwren thettvo geggi indieatmdthattheeamplereateien eccursod mose slowly g deithetepglation1tather thanprimosilydurmg eompSgipleesion. If deordgtem iesuspogtgdidhs ocit sited be confiomed bychaitsidrOie chromgtoeradme oonditionsitempergssrei pH eee. sg-oeegorslow Otg egte sh or0etceptmgco-umntempeeaturewi1iusuelly speed or shawlhe rateotsampleosaotion wiido predic He offo l gnpeekihgpe. For the sgmpleoO Figure hicheetsmhtraiureccoeieeeiee sgmple regction wS ilegPi a a 0 010 386 ehl stows hegeeattieg. ts t