POPULAR CONFIGURATION GCs
Educational TCD
General Operating Procedure
1. Check tomakesure that theTCDfilamentcurrent isswitchedOFF. Plug inand turnonyourGC. Allow
theTCDdetectoroven toreach temperature(100
o
C)andstabilize. With the“DisplaySelect”switch in the
UPposition,presson theTCDTemperatureActualbuttonon thefrontcontrolpanel toread theTCDcell
temperature.
2. Thecarriergasheadpressure ispresetat thefactory to10mL/minfor theSilicaGelcolumn. Lookon the
right sideof theGC for thecarrierpressure that correlates toa flowof10mL/min. Becausedifferent
columnsrequiredifferentflowrates, thecarrierheadpressuremaybeadjustedby theuserwith the trimpot
above the“CARRIER1”buttons. For thisGC,carriercylinderpressure isnormallysetat30psi,which is
10-20mLhigher than thecolumnheadpressure. Thecolumnheadpressure is thepressuredevelopedby
thecarriergasas itflows through theanalyticalcolumn.
3. Makesure that thesetpointandactualpressuresarewithin1psi.
4
.
DamageordestructionoftheTCDfilamentswilloccurifcurrentisappliedintheabsenceofflowingcarrier
gas. ALWAYSverifythatcarriergascanbedetectedexitingtheTCDcarriergasoutletBEFOREenergizing
theTCDfilaments. Thecarriergasoutlet tube is locatedon theoutsideof theColumnOvenon thesame
sideas thedetector. Place theendof the tube in liquidandobserve(a littlespitonafingercansuffice). If
therearenobubblesexiting the tube, there isaflowproblem. DONOT turnon theTCDcurrent ifcarrier
gasflow isnotdetectable. Afilamentprotectioncircuitpreventsfilamentdamage ifcarriergaspressure is
notdetectedat theGC,but itcannotpreventfilamentdamageunderallcircumstances. Any lackofcarrier
gasflowshouldbecorrectedbeforeproceeding.
5. With theTCDfilamentsswitchedOFF,zero theDataSystemsignal. Switch thefilaments toLOW. The
signal’sdeflectionshouldnotbemore than5-10mVfromzeroforabrand-newTCDdetector. Anymore
thana5-10mVdeflection indicatespartialorcompleteoxidationof theTCDfilaments;moredeflection
meansmoreoxidation. Therefore, it isagoodhabit touse theDataSystemsignal tocheck theworking
orderof theTCDfilaments.
6. InPeakSimple,setan isothermalColumnOven temperaturerampprogramasfollows:
InitialTemp.
Hold
Ramp
FinalTemp.
80.00
7.00
0.00
80.00
8. Using the1mLsyringesuppliedwithyourGC, injectsample intocolumn through theOn-ColumnInjector.
7. Clickon theZerobutton to the leftof thechromatogramwindow inPeakSimple to
zeroouttheDataSystemsignal. HittheRUNbuttononyourGCorhitthespacebar
onyourcomputerkeyboard tobegin the run. Youmayalsoopen the
Acquisition
pull-downmenuandselect
Run,
but thisgetsdifficultunlessyouhaveapartner,
sinceyourhandsareoccupiedwith thesamplesyringe.
AutoZero
button
