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Introduction to Modern Liquid Chromatography, Third Edition part 29

Introduction to Modern Liquid Chromatography, Third Edition part 29. 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. . | 236 THE COLUMN of a column-comparison function Fs 61 Fs 12.5 H2 - Hr 2 100 S 2 - S s 2 30 A2 - A 2 143 B2 - Bi 2 83 C2 - Q 2 05 5.4 Values of Hi and H2 refer to values of H for columns 1 and 2 and similarly for the remaining column para meters 5p A etc. A lueetf Fs - 3 iiidi testhat t he two columns are similar in selectivity and can be substituted for each other in any RPC separation for less cliallciigiiicrcparacioiir 1 arger values 02 Fs can be tolerated . The ability of Equation 5.4 to identify columns of equivalent selectivity has been demonstrated for at doUendiParent routine Rl C teparationsAat weredeveloped and used in sevnraldidOerent Saaoraloeiaa l t fan example is given an Fig. 6.10 . Sdftware for the comparison oE column eelecnivity bympane ofEquaaiavld.n t aeSvatrnt eO H S etc. tfaemore than 400 ROC nokmuitcanbeaoceseedat she US ttarmacopeia website http www.atp.org Ua0NF coaampnDn.hsml . OCtasnntsvnly oocnecs nnb of the authoraOcracusrent databpseolvalusa oE H etc. for different RPC columns. 5.4.3 OPhogonal Sopaaanion Just as it ia sometimet nceataey so inoatify ewodifferent ccliarnot ofsnrnlar satedtiv-ity at othsresmeowe need a second column of different selectivity usually combined with a change in mobile phase . Several different reasons for a change in selectivity can be identified. First.whcn dcyclnp.ng areversed-phnse separation a large change in separationsclectivity marbe neepepinrrder to improve the resolution of certain peaks in thscheomatcuram.aesonS1pdaing minOoil drralpvmarofsa samplea oSpu dally imkiiiiwm composition rhorrmaySua convern deal e mmorromponensmidht be overlappeO i rlorner paakin theshromerogram anprnsaofoeumissrd in the final analysio. fnuin asipailaasitpationnnad arior in nSn sndafn ot na i a oeneea for future ramak saS t O minStcobtarn af d np P ununliciautepimnnritiet1tu eidior of the latter wooates ititPeairabirlohavovpaild01e an oltPogonal separation for which seiebtivityaa difflrnntfrom thatoropidedby sUooaioinal .