Page 33 - Basic Gas Chromatography
P. 33

sensor   sensor   oxygen,   for   columns,   time   flame   measurement,   to

      19       for    this   flow    (1)   for    so   flow
             solid-state   measurements   air,   for   cost   The   tubular   linear   1:   retention   the   Since   temperature)   cm/sec



             a    silicone-on-ceramic   open   average   equation   the   this   for   enough   in
             uses   flow   mL/min   methane.   in   The   is   (seconds).   used   velocity

             device   accurate   A   500   to   in   encountered   meters.   from   ty   and   usually   (high   linear   (Continued).


             electronic   permit   to   bubbles.   soap   0.1   of   rates   argon   5%   those   these   with   calculated   be   a-=   tu   (cm)  column   methane   or   air   is  methane   chosen   be   the   of   CASRN       2)   2.2.



       Measurement   sophisticated   microprocessor   using  without   flow   and  hydrogen,   as   such   rates   reliably   can   u,   the   of   as   such   air,   detect   must  conditions   Conversion   Fig.





       and   more   a   gases   measure   to   helium,   $500.   flow   measured   columns,   OT   length   the   peak   not   retained.
       Control   Another,   with   of   used   about   is   small   be   in   is   L   nonretained   does   column   the   not   is



       Flow     coupled   range   a   be   can   nitrogen,   device   Very   cannot   velocity   where   a   detector   but   it   that








        Overview   the   of   carrier   the   in   run   detect   to   thus  column,   (EPC).   a   and   flowmeter   through   is  solution   are  bubbles   defined   a   rate   flow   on   based   At  beams.   use,   to




        Instrument   independent   conditions,   programmed   used   is   the   to   control   flowmeter   soap-film   buret)   or   soap   a   soap   through   gas  carrier   are  meters   light   with   easier   and   type.  electronic



              column,   these   a  during   sensor   pressure   pressure   soap-bubble   The   2.2).   pipet   bulb,  rubber   several   timed   the   flow   made   faster   is   rate.   from   Gas   chromatograph   digital



              the   Under   electronic   the   electronic   a   are   (Fig.   modified   a   After   gas.   accurately   measurement,   electronic   are   meter   flow   the   [   (6)   type
              through   valve.   electronically   An   flow.   increase   by   devices   device   a  (usually   squeezing   flowing   is  bubble   this   Some   measurements   flow   of       film  soap



              rate   purge   and   rate   used   measuring   By   the   one   From   electronic   readout   Q_)       (a)   (a)
              flow   the   of   increased   constant   rate   flow   tube   flows.   of   tube,   calculated.   the   but   an   three-digit   ~~   Soap   meters:

              same   closing   be   can   a   flow   constant   commonly   flow   calibrated   gas   path   the   stopwatch.   easily   $300,   Flow

              the   and   maintain   (decreasing)   a   Measurement   most   electronic   a   carrier   the   into   wet   to   a   with   is   principle,   around   a  provides   2.2.   Fig.
              maintains   opening   pressure   to   providing   two   digital   merely   the   raised   allowed   volume   mL/min   same   cost


        18         gas   order   the   Flow   The   is   which   in   the   a   and
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