tailieunhanh - Introduction to Modern Liquid Chromatography, Third Edition part 10

Introduction to Modern Liquid Chromatography, Third Edition part 10. 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. . | 46 BASIC CONCEPTS AND THE CONTROL OF SEPARATION Figure Knox equation a Plot ofreduced plate height h versus reduced velocity v with A 1 B 2 and C . The total plate height h is shown as a solid curve the three contributions of Equation to h are shown as dashed or dotted curves b Effect of a change in solute molecular weight 6000 vs. 200 Do or temperature 80 C vs. 30 C on Aoersus flow rate. All plots based on Equation with A 1 B 2 andC . So meGu id elines fo r S electing ColumnCondition s Column com ittonso i deidnedascoluiceilength anddiameter particle size end flow rate. Togethertheie sxperimintel choicds bo tdeuuem delesmine the value of N run time and column pressure P. In general larger values of N require longer run times but an increase in the available column pressure can be used to improve the trade-off between N andruntime eitherlargervaluesof Nfor the same run time or shorter runtimes for the sems velue of ie varied for differentdueaoten latgbtdibmtttrstoddteairatiod teperationt Chapter let or smaller diametees ddr l incetated sensitieity when I0eamountoi tuple ts limited 2 reducednowtetesfolLC-MS Sdetibo l .lill retirced ioieeet eansumptien Peak Width and the Column Plate Number N 47 or 4 the use of very high-pressure operation to minimize problems caused by the generation of heat within the column Section . Column diameter dc does not directly affect the relationship between N run time and P but smaller column diameters mean smaller volume peaks which are more affected by extra-column peak broadening small-diameter columns are therefore more demanding in terms of equipmt pressures higher thanabout 5000 psidsorequirespecial equipment Sectíon3ó .5. himns. Apart fromthe iipue oOcalumo Osiciaeia Suchmice aS uolumn condiitons san be guided bnshe shesieisf Peaeion . Tnefo e imgs isp osma wiilosiiunea sample maleaelacwcighs OPn Da Putsheoeppratinn oeSaapocmpleculesSo5ows .