EPAMethod 25 ( true carbon counting )
GC configuration part# 8610-1025
The oxidizer catalyst is operated at
650-700C and is constructed of
ceramicwith a platinum thermo-
couple for long service life.
Page2
A typical calibration stan-
dard chromatogram is
shown at right. Thegas
sampling valveback-
flushes all hydrocarbons
into the catalysts andFID
detector after theCO2
peak. Becauseall peaks
are converted tomethane,
the back-flush peak repre-
sents the true carbon con-
tent of all the various hy-
drocarbons in the back-
flush.
GasSamplingValve
plumbed to inject and
back-flush
Column
12” Unibeads 1S+
24” CarbosieveG
Oxidizer catalyst
650°C
Oxygenor Air
supply
Reduction catalyst
380°C
FID
detector
Hydrogen
supply
PeakSimple
DataSystem
Backflush column
after CO2 toeluteall
hydrocarbons inone
lump
