tailieunhanh - Introduction to Modern Liquid Chromatography, Third Edition part 21

Introduction to Modern Liquid Chromatography, Third Edition part 21. 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. . | 156 DETECTION Figure Measurement of chromatographic signal S and noise N . from the middle of the baseline noise to the top of the peak Fig. . The contribution of S N to precision can be estimated as where CV isthecoefficient of variarmii cquivalciit to -relative standard deviation -RSD . The lower limit of detection LLOD often is described as S N 3 which would give CV 16 whereas the lower limit of quantification LLOQ is S N 10 for CV 5 see also Section 1 . These values of CV are the contribution of S N to the overall imprecision of the method so the overall method precieienis exreetedno be imprecisionattributable toC N oræicodieesmsCe contributerto eexor isiecelhvn half of the dcsiceemethobimnss cisixn S NwiUhace aiweeor lf mCuenve ec the overall mothod ptecision see thu dexeestion . For ecemple ifthe overall method rcqmoeermnretohhnefce morvtha 2 aconirrCetire cfl N of 1 shorie Centii fs cenm-Te ise srei i te thctaS rCvalue o0 rstie50 Coemore is required forsnoxeccl-methodcmpceoisionof 2 . The t nchrce rete rrtir rcnbr imesoveC to sncreatiiig thre ml peducing the noise ce CoeO as summarized mTaek CeliAnincrcasr insipnal foro eioer peak or sameit mryberva labirfr macXangeinnetecterttttinu eor encmcior she use of a UV wavelmedi thxt c on entonàtex maxemumtamois aO-eoetinitd. A mope sensitive deteotoe aino maebeavailrblel o rtthse ent name ordifferent type. Derivatization Section ornthec modifitation of tiic onviyta may made it more receoc ixe tn ttn ceosex eommon ncfsoK ef intractmg the signal teto rnimra hrgeo we-ode ot eample siCicra largresnmper axlume or a sample 0x 0111316 ioeSec . Howaucr cxln 1xr0eteatrr xvirtxadwiU eventually lmitshrp2sribl1 mcrrvoe in sionvtin tirie rceo. Anyredertlbn in peak width should tranolote intoa predoe xnalinceeas3ln pr k hdighslaerale visumed to be con amO sm tkc ll-vareet idcceate le A sr rnomd es SFi .xOC narrow-diamexer 0x100318 0 0 .