tailieunhanh - Introduction to Modern Liquid Chromatography, Third Edition part 47

Introduction to Modern Liquid Chromatography, Third Edition part 47. 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. . | 416 GRADIENT ELUTION changes in run time resolution and peak heights for these isocratic separations as column conditions are varied. When changing experimental conditions during method development for isocratic elution it is desirahlc to first vary conditions that affect values of k and a so as to optimize selectivity and resolution. If a further improvement in separation is desired byvaiymgcolumnconditions the previouslyoptimizedvalues of k and a will noschanoeeor isncradic separation. With constant values of k and a the interpretation of subsequeny eyperimentssialsosimplifiea as onlybnandsvnrime can vradient elutian ide situation ismoreeamplicaied asvaluysvf k vary with codnnn lengniiVidflvwrateiEq. ekor valuet ebei mndisSneemiOn constant wlEle oaryieg column kocmtioksrororadeentelulion itrs necerraiyto hold values of ok L oor rtae e Eq. yryiogeopofl i nvl o oohimne nkdi Ly provided ghee the voliimk Oiametcris norcganoedl. Voi clanges i column 1 eeyth L or flow raseblhaoneomivanschaggein i rndiico limeínletVemolScvnvenieuv way of mainigminu vkntrnm vhhiu of kod gratUeet time shoulkbechaogei byigenv c or x. Fgkan nifyidcOhegeinF geadiem time shoubdUe chgogea by l in Osneratéi i nns kf koro results in n kUangr meubtim gahangerse gr oa t balun of LoejFersdllinehe same relativ echenoem r un -1 tang bshyosthntnalues ota y g meintameV by changioggradirnlsimei Socratic 100-mm Rs a I----------- ---------- 0 2 4 . . 6 Time min isocratic 300-mm mL min Rs h _A_ I 0 10 0 30 Time min c isocratic 100-mm mL min Rs _A 0. Time min Figure Isocratic and gradient elution compared for a regular sample and change in column length or flow rate. Sample and conditions as in Figure except for varying column length and flow rate as indicated in figure 55 B for isocratic runs a-c 0-100 B for gradient runs d-h . Note that actual peak heights are shown woi normalized to 100 for

TÀI LIỆU LIÊN QUAN
TỪ KHÓA LIÊN QUAN
crossorigin="anonymous">
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.