The inlet and column is able to hold the pressure when no samples are being run. However, once a sample is injected and analysis begins, the front inlet and column pressure immediately decrease. How can I fix this?
The front inlet is able to hold the pressure when GC is idle. However, once a sample is injected and analysis begins, the front inlet pressure and column flow rate immediately decreases. How can I fix this?
Can you provide a few more details such as the inlet type and the method parameters that you are running?
The inlet liner we are using is an Ultra Inert, split, low pressure drop, glass wool. Product number 5190-2295. This is a newish liner (it has never been used before but I think it is really old). It was installed only last month.
Even when I do blank runs (no sample is inserted, initial oven temp is 70 degrees Celsius), the pressure drops immediately. However, when I ramp up the temperature to 230 degrees Celsius, the GC is able to hold pressure and flow rate.
See below for method parameters (we are analysing volatile fatty acids and have been using this method for a while):
Septum Purge Flow
Flow after 2 minutes
Agilent, ZB- WAX plus
Internal Diameter (ID)
0°C - 250°C
Post run flow
Maximum oven temperature
Hold time (min)
Run time (min)
Flame Ionisation Detector
H2 Fuel Flow
Makeup flow (N2)
Just fixed a few formatting issues with the table contents. Here is the revised method parameters table, Thanks!
The septum/loose septum nut was the problem
Retrieving data ...