Page 49 - Basic Gas Chromatography
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35                                             and   whose   peak   book   interaction   some   in   (b)   that   this   in   (see   is   the   order   on   the   as   (18)   can   As   one.   the   different.   b)/2a.
            e.Doublet                       doublet.   (e)   sorptions   peak,   or   the   is   It   the   in  figures   ideal.   shows   3.2   like  peaks   indicate  usually   Theory   applications   it  However,   in  possible   depending   defined   is   shown.®   greater   than   While   one.   is  definition   +   (a   =   T   is:





            d.Tailing                       tailing,   (d)  fronting,   repeated   after   distribution,   a   Gaussian.   or   all   in  shown   not   are  peaks   some  undesirable   Figure  process.   Broad  samples.   and  columns   Rate   The   (see   GSC  column   situation.   the   narrow   as   as   fronting   or  tailing   asymmetry   of   as  height   peak   TF   a   have   than   less   TF   a   USP   the   and  height   peak




             c.Fronting            NU    TIME   (c)  broad,   times  retention   is   solute   normal  being   is   it   and   whose   that  indicate   chromatographic   actual   packed   slow   too   packed   improve   peaks   the   as  classified   extent   The   b   =   TF   a   the   of   10%   will   peak   yield   will   unfortunately   but   the   of   5%   at



     Symbols                                (b)  ideal,   (a)   of   given   a   for   as   ideal,   chromatograms   usually   in   occur   in   are  transfer   in   some   to   done   make   to   separations.   be   3.3).   at   tailing   a   fronting,   definition,   measured   is



     and    b.Broad                         shapes:   aggregation   result   approximated   the   real   peaks   the  during   common   as   be   can   goal   can   asymmetry.   (Fig.   measured   equation,   symmetry,   used   tailing

     Terms,                                 Peak      The   be   represents   those   Nonsymmetrical   place   sometimes   more   are   mass   of   Sometimes,   little   best   the   peaks   the   of   (TF)   are   b   the   commonly   of  definition


     Definitions,   a.ldeal                 3.2.   Fig.   randomized   desorptions.   can   shape   that  shape   except   for   taken   has   that  shapes   Figure   3.2   kinetics   the   chapter).   5),  Chapter   chromatographer’s   achieve   to   Asymmetric   location   the   factor  tailing   and   a  Both   be   from   seen   opposite   The   a   is   > This   latter   The












     Terms   definition   (16)   the   factor.   relation-   (17)   retarded   solute   given   in   retention   non-   means   mobile   another   in   10%   with   example,   versus   injec-   stationary   that   most   Chapter   similar   data.   retention   extracted   one   of   a


     and                 chromatogram,   retention   exact   is   a  which   any   at   spends   a   a   than   This   the   in   For   are   solute   our   90%   on-column   the   show   fact,   in   in   GC.   is   chromatog-   HPLC   of   produce

     Concepts   computational   the   the   solute   a   at   one.  than,   phase   solute   have   longer   0.167.   or   was   it   instant.   percentages   the  Clearly,   in   B   phase,   how   into   numbers   material;   Similarly,   temperature   chromatography   liquid   and   meaning   the  fraction   independently   they  result,



     Basic               a  from   for   case   at   arrive   yielding:   which   rate   less   mobile   average   might   A,   times   1/6   of   any   phase,   stationary   sorbs   These   phase.   permitting   TLC   the   to   act   a
           the             the   To   8,   to   fractional   or   the   the   5   is   k),   16.7%   at   relative   phase.   explain   of  it   injected   compare   principle   As
           yields        obtained   was   equation   extent   the   to,   in   time   solute,   retained   +   column,   phase   the   stationary   the   in   to   90%   state.   the   stationary   programmed   column   understanding   in   molecules   process.


           14      _ Vm   v,   be   as   related.   1   ath   or   equal   solute   of   typical   1/(1   9,   stationary   the   time   used   on-column,   vapor   of   of   for   chromatography,   to
           and     R=    can    into   R=   the   be   of   fraction   a   is   it   factor,   the   stationary   of   in   its   be   the   all   the   defined   parameters   in   similar   solute
           13,             evaluated,   inversely   measures   column,   fraction   that   through   factor   the   of   also   into   into   is   extraction.   chromatographic
           10,           volumes   are   substituted   the   always   the   example,   retardation   the   in   in   90%   sorbing   can   injected   goes   “evaporate”   understanding   factor  just   two   helpful   concept   individual
           equations   factor:   these   of   easily   is   factor   k   and   is   16   factor   through   will   value   the  represents   alternatively,   For  phase.   means  which   Its   passed  solute   was  84.3%   retention   a   and   phase   for  affinity   percentage   factor   is   B   When   10%   to   directly   goes   our   thin-layer   in   these   be   may   the   that   liquid-liquid   that   the



           Combining   retardation   both   retardation   R   that   Note   equation   retardation   passage   Its  moving.   also   and,   mobile   5,   of   peak.   the   as   and   B,   with   mobile   greater   greater   a   A.   for   retardation   work.   only   and   necessary   not   solute   in   aid   will   retardation   factor   Rr   use   to   it  finally,   note   to   in   Shapes   noted   have   during




    34        the   of   Because   ship,   The   its   in   is   It   time   the   factor   retained   that   phase   solute,   the   the   spends   84.3%   The   tions   phase   is   it   the   of   R   9,   The   the   to   raphers   And   factor   concept   Peak   We   another
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