Packed column problems-setting up N2O analyses on an old GC

[NewToTheGC]

Hi all,
I'm setting up an old Varian 3400 for N2O analyses. I've got the GC up and running, and the integrator working.

I've tried 2 columns now, and have inadequate separation of the CO2 and N2O peaks. The column I have should be more than adequate according to the literature(20ft HayesepD, 1/8") , and I've adjusted flow rate, temperature, carrier gas, etc. The tops of the peaks can be separated, by a max of say 10s - which SHOULD be lots, but the bases of the peaks are combined. I've played with the time functions ... and everything I can think of.

The plumbing is pretty straightforward - on-column injector ----column----detector, so I doubt dead volume is an issue (though it could be if the injection system or detector aren't plumbed correctly?).

Any other ideas?
Sure could use some...
-Helen

[chromatographer1]

Look at the plate number of the column and the plate number of the literature chromatogram. Are they the same?

Improper installation can add dead volume and ruin separations.

A column fouled with non volatile sample will also have a low plate number.

Who prepared your column? Was it packed in house? Was it commerically packed? Was it tested for resolution before you used it?

Contrary to popular belief, it is not always easy to pack a good porous polymer column, especially in long lengths. Been there, done that.

You could also be injecting more sample than the column is capable of handling.

CO2 should be a nice symmetrical peak, is it? If it is not, then you have a bad column.

Your flow rate could be too slow or you could have a front side leak.

Golly not knowing how broad your peaks are in seconds, it is hard to say more.

Good luck,

Rod