General Operating Procedures continued
POPULAR CONFIGURATION GCs
BTEX & Environmental
Direct Injection
Thistechniqueisusefulforvolatileandsemi-volatilecompounds,butistypicallyusedfordieselandother
compounds thatdon’tpurgewellfromaqueousorsoilsamples.
1. Perform
DetectorSteps
1-4, thenproceedwithstep twobelow.
2. Load or create a Temperature
Programforthecolumnoven. Youcan
create an isothermal or ramped
temperatureprogram;decidingwhich
to use depends on the sample being
analyzed,andthegoalsoftheanalysis.
There are several preset
.tem
files
includedwithversion2.66andhigher
of the PeakSimple software. If the
analysisrequiresthecolumntobehotter
than150
o
C, it isbest todisconnect the
column from thePIDdetector. The
PID represents a cold spot inwhich
higher boiling analyteswill become
trapped,nevermaking it to themuch
hotter (300
o
C) FID for detection.
Also,when thecolumn isheatedover
150
o
C, stationary phase bleed will
adhere to thePID lampwindow. Thehigherboilinganalytesand thecolumnbleedwillcreateacoatingon the
PID lampwindow thatwill interferewith theanalysis. ThePID lampwindowmaybecleaned in theeventof
contaminantcondensation,buttheresultingchangeinthePIDresponseusuallyrequiresdetectorrecalibration.
Tobypass thePID, turn its lampcurrentOFF, thendisconnect thecolumnfrom thedetectorby loosening the
swagelok-typenutfromthebulkheadfittinginthecolumnovenwall. RemovethetubingthatconnectsthePID
exit to theFID/DELCDby loosening thatnut. Place theendof thecolumn into theFID/DELCDbulkhead
fittinginsteadandtightenitinplace.
3. While thedetectorsareheatingandstabilizing,prepareadieselsamplebyshakingaknownweightof the
samplewithameasuredvolumeofmethylenechloridefor1-3minutes. Allowanyparticulatestosettlebefore
drawingthesampleintothesyringe.
4. Useaclean, standardglass10µLGCsyringewitha26gaugeneedle. Fill thesyringewithsample,and
workoutanyairbubbles. Depress theplungeruntil1µLofsampleremains in thesyringe.
5. Zero thedatasystemsignalbyclickingon theAutoZerobuttonon the leftside
of thechromatogramwindow. Or,make the firsteventZERO (at time0.00) in
yourevent table.
6. Begin theanalysisbypressing theRUNbuttonon theGCor thecomputer
keyboardspacebar.
7. Quicklyandsmoothly insert thesyringeneedle into theon-column injectionport,and immediatelydepress
theplunger.
AutoZerobutton
PIDdetectorbypass forcolumnoven temperaturesabove150
o
C
Thecolumn is inserteddirectly into theFID, bypassing thePID.
