Linerpluggedwith rubber
septums forstorageor transport
PTV Injector linercapped
Theory of Operation continued
INJECTORS
PTV -ProgrammedTemperatureVaporization Injector
Foronline thermaldesorption, thePTVcanbeplumbedwith
agassamplingvalve. Inthismodeofoperation,thePTVfunctions
as a sample loop, trapping and concentrating compounds for
analysis.
2) OfflineThermal Desorber
3) OnlineThermalDesorber
When thegassamplingvalve is inLOADposition, thePTV
injectorcanbe loadedwithsample through thesample inletand
outlet. ThePTV injector isat40-60
o
C. Analytesare trapped in
the injector’s linerpacking.
LOADPosition:
(Relay “G”OFF)
In the INJECTposition, thePTV injector ramps to300
o
C,
vaporizing the sample. The carrier gas flow then flushes the
desorbedcomponentsonto thecolumn(s). Thevalveshouldbe
rotatedback to theLOADposition after the components are
transferred to thecolumn toavoidsmearingandpeak tailing.
INJECTPosition:
(Relay “G”ON)
Foroffline thermaldesorption, theSilcoSleeve
linerpackedwithadsorbentsuchasTenax-GR
TM
is
loadedwithsampleoutsideofandseparate from
theGC. Althoughthebestanalysisisobtainedfrom
afreshsample, theendsofthelinermaybeplugged
after loadingsamplewith rubber septaorcapped
withrubberendcapsforstorageor transportation.
Turnoff theflowbeforeremoving the injector liner
byactivating relayB,whichstops thecarriergas
flow. LeavetheEPCflowoffuntilthebeginningof
theanalytical run (see theevent tableat right). To
replacetheliner,unscrewtheseptumnutandseptum
protrudingfromthefrontoftheColumnOvenwall.
Remove therubberseptaorcapsfrom the linerand
slideitinwiththegashtowardtheoperator. Replace
andclose theseptumandnut. With thecarrierflow
still turned OFF, start the run. When the PTV
injector reaches temperature, the carrier flow is
turned ON and the analytes are swept onto the
column.
LOAD
INJECT
ExamplePTVas
offline thermaldesorber
event table
