tailieunhanh - Introduction to Modern Liquid Chromatography, Third Edition part 44

Introduction to Modern Liquid Chromatography, Third Edition part 44. 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. . | 386 NORMAL-PHASE CHROMATOGRAPHY Non-localizing B-solvent CH2CI2 chci3 Basic-localizing B solvent MTBE THF Non-basic localizing B-solvent Ethylacetate ACN Figure Use of seven experiments for the optimization of solvent-type selectivity in NPC. A-solvent hexane heptane or ethoxynonafluorobutane or for s CFfiCf . For a very strong localizing B-solventuse w-ori-prnpanol. the purification ofcrude samples thcsqvnatioiiol isorncie ortho nalseparation samples that contain hydrophobic interferences samples thos contain oerfpoiar aodysor . unretained in near-100 water by RPC The pz n fytfc ofp i rr sy i sL Oeration of organic-soluble samples is usually best earned out wish NPC anOasLlLcacoComm Ths semooal of solvent from separated fractions is easier for the organic solvents used in NPC compared with the higher boilinr wcssr rood m RPC. Forges values osa fpr diet sotaesto be purified are usuallyjsossiblewith NPC and silica columns meaning that larger sample weights oanbeinjected otlieo cosd i o s tOe srme . FüiaUi .diei ec sS TTC can becnovemenf Soothe prehneeirro roino nf Oreetionsfrompreporatioe NPC. As notsdabove Slcfipn n . .5 isrmmcrcnpoon 0s ooeusuahy moohCettor separated Co msnoof OSOC withsilsca noanyisemere areoesilh separated by RPC lo smayFe preferabk tons 0 PC if rsiles such sompres uniess prior expenpncewithreisSsdsomhlrssuggeHt otWoewise. prHr proposed method hassrpassoed ah afthe compounds in psioriples tWe selectivity stan orthogonaemrtPod sOoCd lie as 0iffsrrntslpptei01efrpme0os of the orisliynlmethod. IHtda pastsomeworksrs hase acriHiedthat separoWons based on adiStesaysprinciple . NPCvs. RPCipslmpreOkoldtP provide a large enough differenceimueleetivItysothutanapalsef pcakspveriappeOin pna mesiiod METHOD-D EVELOPM ENT SUMMARY 387 will be separated by an orthogonal method. While this suggests the use of NPC for orthogonal separations it is also possible to design two orthogonal RPC methods Section .