Introduction to Modern Liquid Chromatography, Third Edition part 42. 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. . | 366 NORMAL-PHASE CHROMATOGRAPHY hydrocarbons according to the number of double bonds in the molecule but with little effect of differences in alkyl substitution or solute molecular weight. Similarly lipid samples can be resolved into mono- di- and tri-glycerides as well as other compoundclasse s . Isomeric solutes are usually much better separated by NPC than by RPC as seen in l igind- methyl-substitutedanilines Figure C2 or dimethylplus ethyl subst tueedani n t2 and Csoe trlmeBiyl- mednylethyl- and n-propyi-substitutedaniimet .The R2C ratestion of i-2mens Ctaiulinetl is generaUysiyCla2 withmarginal separation while the reverse is true for NPC more varied valsesoffe tog Ulffereyti-omers anUdetSee tepoeuCon . The -uestur isomer-selectivity oUNUC v sus CPyisalsoshownby -he rangeiuvalues of k for each set ot ieomeus giat -s 1Ce ratis nf oselueutor ths must eetainadandleaut retained i-omers rangeui isg Fig. . Thespreudinls eslers fcsuginup mf isomers Ce Cs-oe C3 ran-ns from versus for NPC wVicB - muny-imee larger foePtBC. When a-o isomericcempoirnds ngnvpUifilculetn tecRite U- R2Ui Section NPCwIU usuaUy pnove more effective. Thgs-forpaenarativa nei i eti -ns Chapter Sb wheresVe erges-2ossi21 g valuue tin arhUssfrabie NPg ce thn tiiico column is strvn y recummonded esutheteysrstiec oSanlilraiiepmerc for chirae isomers sa CPruteee4 . Fne a2evsawof -huRPC separation of isomers see Section for a furthee-2sectsioFvSifhm8cteng2enon y NPC tle Sece-yu . If in doubt esto chetiieraseyiarc tivnOs Base on NPC peRPCreSeniion a simple SuU t to sury tl-npu-aeityoe tCn mobiiepnere. Ofre-insion anereases with increased nsobile-phasu pnheritv RPC trmeolved ifee-in-too Ufceeaees wink increased nwVi-nlpe-asrUo as ts NPTcan decstpmed. Tins t e-0olds njhe-Vei nfn stationary phuse Is ypgounnn nenoeReP sI-uvi anywhelReitPe mobiie 1 -2 C aqueous or nonaqueous note thatwateris themost prlar ofall sohents .
