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- Posts: 4
- Joined: Tue Nov 15, 2022 11:34 pm
- Location: United States
I'd like to thank you all in advance for reading the post and posting potential solutions
We recently replaced the FID collector assembly and the jet of the GC, but after this we could not see any alkene or alkyne peak. We have trim ~10 cm of the outlet of the column.
I am not an expert on column, but the phenomena looks like the column is activated due to the contact with air when changing the jet. Should I trim the column outlet even more? such as 20~50 cm?
Please see details of the column, calibration gas used and the operation configuration below
GC agilent 7890B
Column 19091P-S12 (Fused silica, 0.32mm ID, 27 M length, more information here: https://www.agilent.com/store/fr_FR/Pro ... 19091P-S12 )
Operation configuration:
Inlet
Manual Injection Split 1:80, He flow 5 ml/min, Heater 250 C, Pressure 16 psi Septum Purge 3 ml/min
Detector
Heater 250 C Air Flow 400 ml/min, H2 40ml/min, Makeup 27 ml/min
He flow 3.5 ml/min
Oven
60 C
Ramp 1 20 C/min to 80 C
Ramp 2 30 C/min to 190 C
Our inlet doesn't have a liner, and all we do is inject hydrocarbons into the GC.
Calibration Gas composition
The bold font denoted the gas we could not observe
2 METHYL 2 BUTENE 0.0500 % - this one is higher (than previous, "normal" calibration)
1 PENTENE 0.1000 % - none shown
ACETYLENE 1.000 % - much lower
CIS 2 PENTENE 0.1000 % - much lower
METHYL ACETYLENE 1.000 % - much lower
CIS 2 BUTENE 0.3000 % - this one is lower
HEXANE 0.0500 %
ISOPENTANE 0.1000 %
N PENTANE 0.1000 %
TRANS 2 PENTENE 0.1000 %
ARGON 0.2000 %
1 BUTENE 0.3000 %
1,3 BUTADIENE 0.3000 %
ISOBUTANE 0.3000 %
ISOBUTYLENE 0.3000 %
N BUTANE 0.3000 %
TRANS 2 BUTENE 0.3000 %
PROPADIENE 1.000 %
PROPYLENE 1.000 %
CARBON MONOXIDE 1.500 %
ETHYLENE 2.000 %
PROPANE 2.000 %
CARBON DIOXIDE 3.500 %
ETHANE 4.000 %
METHANE 5.000 %
HYDROGEN 12.00 %