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. TheTCDovenblock isset to100
o
Cat the factory,but isadjustableby turning the trimpot
withasmallbladescrewdriverwhileobservingtheTCDBLOCKsetpointtemperatureonthedigitaldisplay.
The trimpot is locatedon the topedgeof theGC’sfrontcontrolpanel,under thered lid.
2. AllTCD-equippedSRIGCsare testedwitha1m, 1/8” stainless steel silicagel-packedcolumn. The
carriergasheadpressure ispresetat thefactory to10mL/minfor this typeandsizecolumn. Lookon the
right sideof theGC for thecarrierpressure that correlates toa flowof10mL/min. Becausedifferent
columnsrequiredifferentflowrates, thecarrierheadpressuremaybeadjustedby theuserwith the trimpot
above the“CARRIER1”buttons.
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 theTCD filamentsswitchedOFF,zero thedatasystemsignal. Switch the filaments 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
o
C 7.00 0.00 80
o
C
7. Zero thedatasystemsignal(clickingon theAutoZerobuttonat the leftedgeof the
chromatogramwindow isoneway todo it), thenstart the run (hit thecomputer
keyboardspacebarorhit the“RUN”buttonon theGC).
8. Injectsample. Injectionvolumesof0.5mLforgasand1µLforliquidisrecommended
toprolongTCDfilamentlife.
AutoZero
button
DETECTORS
Thermal Conductivity Detector - TCD
