Chromatography Forum

While conditioning the column in a GC-FID, should we be concerned with the inlet pressure or column pressure on the instrument display panel? What is the difference?

While conditioning the column in a GC-FID, should we be concerned with the inlet pressure or column pressure on the instrument display panel? What is the difference?

Isn't inlet pressure equal to the pressure at head of the column ?

The most important thing is to provide stable, sufficient carrier flow through the column.

While conditioning the column in a GC-FID, should we be concerned with the inlet pressure or column pressure on the instrument display panel? What is the difference?

Does your GC give separate readouts for these ?, and are the values different ? What kind of GC is it ?

Peter

It is Agilent 7890A GC.

For answering one question out of 3 you get 33%.

Peter

Is conditioning a capillary column really necessary? The column has been previous run, the check out chromatogram included in the box.

Isn't conditioning in most cases a carryover from the old days when "we" made our own packings from stuff like SE phase and Chromasorb W and then packed into stainless steel tubing?

Consumer Products Guy is right: You shouldn't have to condition a new column (as in factory sealed) as long as you cut enough off from both ends (factory sealing the column by flame destroys some centimeters of the stationary phase).

In fact, I've installed a new VF5-ms without any conditioning in one of my Magnum ion traps some days ago. The background was negligible (most abundance was at masses 55,56 and 57: pumping oil).

And what works for a trap surely works with an FID too.

there is no thing called column pressure.. whatever when i adjusting GC pressure i depend on the design for EX:
the inlet pressure of carrier gas in my GC is 80 and outlet is 40 controlled by EPC .. otherwise the measuring will be wrong, so check your design manual it will help you.


i hope this help

As long as you have carrier flow (ca. 1 mL/min) and positive "Inlet Pressure" (i.e., head pressure) you should be fine to condition your column. NOTE: Check air leaks around the injector first. It would be BAD to "condition" a column with an air leak in the inlet.

However, as previously stated. It is probably not necessary to condition a modern column. Especially if FID is your detector. I don't usually do it on my MSs unless I already see problems after the first couple analyses.

I think what you mean by "Inlet" and "Column" pressures is the pressure listed when you push the "Inlet" or "Column" buttons on the front panel of the GC correct? Both of these pressures should be exactly the same as they provide a read-out of the inlet head pressure. Verify yourself by adjusting column flow and watch as both change to the same value. I think Agilent lists it under both buttons as the head pressure is a parameter of the inlet and the "head" of the column. It's a shared parameter.