tailieunhanh - Introduction to Modern Liquid Chromatography, Third Edition part 31

Introduction to Modern Liquid Chromatography, Third Edition part 31. 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. . | 256 REVERS ED-PHASE CHROMATOGRAPHY FOR NEUTRAL SAMPLES normal-phase chromatography NPC . As RPC involves a less polar column and a more polar mobile phase the two phases can be regarded as interchanged or reversed. The first RPC packings were made from silica particles that had been reacted with CH3 CnSiCln so as to render the surface nonpolar. A nonpolar stationary phase was then used to coat the particles allowing their use for reversed-phase liquid-liquhij artition chromatography 2 aHPLC teclmiquetiiat is rarely used today. BondeC-chase cohmuis eepresented die neat major advonce re hiohe performance RPC. Oariy Ci8 rolumnrod iCistypowerepreparedby tCeaovalent attachmeni Spelg roda yk Ck xmic gr riOicapareicles 3 C .Thiswae CoUoweda few years i Uerl- themiroductionoraoiumntwPereindiyiPurl deogroupr rather than a Ciehglymer were attached to the particle Section . Beginning in the early 1970s RPCoeCuivoo oC thrlemor typeececouted mcreasixglabecaureortheir many eP0-19A0s the usa eO RhCunderwect encxploeivcgrowtO in popularity oaocral nu dredsrharptiodiarc cited in 5 foreheperioO 9C6te 1979. Wncreasrarlieraupl eetipnsoS Rae empyasioeCiCe sopatation of more hydrophobic iioophid3 eamciee theeiastic papeegy Hcrvcth 6 demonstrated that RPC Hpfaieo Eeosed ionhe cocarccion eC reCatiyeb poiac compoungy especially ari i i We compleo oO hifchenucoC hoc seA iiitlc lecrr RPC war further adapiedeorthssecarationptioeiocViecpmpoundt rncioding enantiomerr by the addition oi ien-paiemg cempocnds de Rip moteio phate c c ogC zr chromatogrphhy Section . e. In diegot Cl 7 i teverol geoupsrepor-ed the hcot RPC sepaoatioepof eree papti e chdproeeine usinysdnri-cna-n wid3i0orr column pce Cngs. TedaCi RPCic tCaeoe1 aau Od0 cioPc and aao B foc a substantial mojorgyofcll jlPCOC se cectiyns. RETCNTWN Retention in RPC was discussed briefly in Section . Because very polar molecules interact more strongly with the polar mobile phase these compounds are less retained