Page 158 - Basic Gas Chromatography
P. 158

Temperature   of  PTGC  Disadvantages   and  Advantages   145      general-  useful   :  Qs  Cy   But  temperatures.   G2   G,   at  cross   lines   a   at  separated;   the  temperature   can   it  reverse,   work   the   a   for  temperature      4   4   4   1   i   A   i   1   TL   4.   i   I   I   dew   4.   4   1   75   70   65   60   55   50   45  35 40   30   25   20   18   10   5S   0   95   90   85   80   (min)   time  Retention   (a)



   Programmed   the  draw   lower   their   be  cannot   higher   a   to  orders   example   for   See   the   [2]  complex   important   however,   powerful.   PTGC   whose  components   often   is   it   isothermal   an   homologs   of   at   run   separated   like   looks   this   for   programmed  using   which   in   run   in   used   a  250°C,   to   temperature   the   analytes   the   yielding   the  illustrate   are   times   when   low-bo





         we   can   at  better   m-fluorotoluene;   they   at   but   elution   for   peaks.   [1].   increasing   decrease   decreases)   quite   is   less   and   Overall,   very   OF   range,   for  suitable   range   wide   isothermal   totally   which   temperature   improved   programmed   temperature   up  minute   Increasing   of   column,   runs   two   retention   are   linear   of
         observation   usually   and   140°C,   first,   elutes   common   of   pesticides   of   volume   slightly   efficiency   effect   (selectivity).   is  PTGC   DISADVANTAGES   contains   wide   a   be   a   of   An   9.2a.   being   from   paraffin   isothermal   isothermal   per   temperature.   coefficients   the   the   the  series,   they   separation





         this   are   n-octane   temperature,   toluene   not   misidentification   consequences   Increase   retention   decreases   (usually   on   a  minor   and   GC   by   over   will   which   separation   Figure   (<Cg)   C,5   the   best   significantly   such   one   the   degrees   partition   through   between   but   the
         From   separations   solutes,   that   the   is   it   in   chlorinated   the   of   Temperature   and   changes   increases   temperature   Usually  it  is   thermodynamics   significant   AND   analyzed   extend   the   in  shown   elute   to   the  probably   be   can   shows   than   less   8   at   isothermal   the   faster  move   differences   homologous   conditions,   facilitated

         temperatures.   GC   that   two   the   At  140°C.   temperature   While   true.   resulting   with   list   a   is   of   time  Retention   factor  Retention   (a@)  Selectivity   (N)  Efficiency   of   increase.   very   are   ADVANTAGES   being   points)  (boiling   temperature   consider   sample   components   minutes   is   this   separation   9.2b  Figure   50°C,   programmed   the   than   decreases   they   so   major   a   For





         low   ization   at   is  reverse   happen,   Hinshaw   Below   analysis.   Effect   effect   always   column   effects   sample   one   example,   kerosene   lighter   90   so,   The   starts   is   higher   run   column,   times.   Some   PTGC.   programmed
   144   at   look   about   lower   of   GC   ¢   *   *   *   The   on   a   If   sures   select   the   over   Even   ature.   ture   and   the   tion   of   under
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