Hi

I'm hoping someone can give me the following:

a) a calculation for GC detection limits - amazingly, my searches on the web have not turned up a standard type of calculation yet - for comparison purposes of H2 detection limits between labs -

b) a good method to revitalize Plot Q columns?
We have trouble with loss of resolution over a period of ~ 6 months...but we have invested alot of money w/ the columns and would rather regenerate if possible? I have tried standard heating/baking out..but does anyone have any other hints?

thanks
karin

Hi!

If you wont regenerate the Plot Q Column you shoud heating up it to about 180 oC and simultaneously transmit carier gas. This method must go on 12 hours.

Martin

Hello Karin,

Detection limits for H2 is a difficult one as it's related to the instrument setup and detector type. If you're using a TCD you'll obtain the best sensitivity using argon or nitrogen as the carrier/reference gas. You'll be able to drive detection limits much lower by using a pulsed discharge detector (PDD or PDID).

As the previous post states, regeneration of a PLOT Q column will take an extended bakeout. I'd recommend baking at the upper temp limit for at least 10-12 hours. Ultimately it depends upon what has contaminated the column. If the column is contaminated with very high boiling residue, then a bakeout is not likely to help very much because of the very high retention of the phase. Ideally you should bakeout the column in backflush mode to more efficiently remove the contaminant material (shortest pathway out).

Best regards,
Jason Ellis
Agilent Technical Support