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column conditioning
Posted: Fri Dec 07, 2007 12:41 am
by ece
We just got a brand new metal capillary column from restek and we're getting ready to install it. However, we need to condition it. We have an FID and the manual has said to not connect the other end of the column to the detector when conditioning. Although we're using Helium as the carrier gas I am concerned about leaving the other end out in the oven or in the open air while it is conditioning, as when we are done we will to cap it, turn the unit off and uncap it anyway install it onto the detector anyway once it is cool.
Why do all the manuals say leave it unattached to the detector while conditioning?
Posted: Fri Dec 07, 2007 1:27 am
by chromatographer1
The primary reason is the bleed off the column as it is first conditioned will contaminate your FID and increase the noise level, raising the limit of detection of your detector.
Leaving the column in the oven is no more a problem than leaving the end of the column in the detector as it is flowing air and hydrogen to the flame tip.
Just make certain the column end does not enter the space occupied by the oven fan.
best wishes,
Rod
Posted: Fri Dec 07, 2007 5:42 pm
by ece
thanks, rod. now that i think about it i can see how that can happen.
one more question: before i put it into the detector should i leave the flow of helium on? or should i just cap it and install it as quickly as i can and then run helium through it again?
Posted: Fri Dec 07, 2007 5:58 pm
by chromatographer1
Leave the flow of helium on. Any 'capping' you do may contaminatethe column end and you wouldn't want to put a dirty end into the detector.
best wishes,
Rod
Posted: Sat Dec 08, 2007 4:23 pm
by Consumer Products Guy
(1) Capillary columns most often are put through QC test which includes running a sample, and print-out of that is most often included, so the column has already been pre-run.
(2) My guess is that the part about not connecting to an FID is a hold-over from the old packed column days and of less importance with capillary columns (with smaller amounts of phase) and bonded phases.
Posted: Mon Dec 10, 2007 6:46 pm
by ece
thanks again for all t he info.
yeah we got the QA report from them and it looked golden on the baseline. i'm still a little concerned that i should condition it, b/c of the heat sealed ends. how far down should i score it, approximately? should i still condition it anyway?
Posted: Mon Dec 10, 2007 7:10 pm
by chromatographer1
I would cut off 3 to 5 inches as a rule. Rules are made to be broken. Rules are also made to be adjusted.
best wishes,
Rod