ASTM 3612/TOGA/DissolvedGasGC
RevisedOctober 2013
The temperaturepro-
gramandevent table
had tobemodified from
theprevious ones to
run this samplebe-
causea10minute
“headspace” timehad
tobe included in the
analysis. This required
holding the initial oven
temperatureat 50de-
grees for 13minutes
insteadof 3minutes as
before.
Also theEvent table
wasmodified to shake
( RelayD ) andheat
the40ml vial ( RelayF) for the first 10minutes of the
analysis.
Theexistingheadspace in the vial was alsopurged for .2
minutes ( RelayEandRelayC ) at the very beginningof
theanalysis. Thismay not benecessary or required for
real sampleswhichhavebeen inserted intopre-purged
vials and remained in the40ml vials for some timeprior
toanalysis. As the samples sit in the vial, they areal-
ready in theprocess of equilibrating theheadspace sono
flushingmay benecessary.
Notice that topurge theheadspace in the vial at time
0.05minutes, RelayC is turnedon first, andoff last, so
that thepurgegas can flushout theheadspaceand then
depressurize through theRelayC solenoid. When the
vial is pressurizedat 9.8minutes however RelayC re-
mains off until 9.8minutes so theheadspacegas has a
few seconds tohomogenizebeforebeing released
through the loop.
