Merlin microseal or Septa... should they really “SEAL” ?..

I visited a customer last week who had issues with septum particles in the injection port. Their analytes were reacting with the siloxane-septa residues resulting in poor precision. The solution was using septumless system, like the microseal.

All the GC’s used these seals, which worked very well. Interesting enough they shared that all the seals start leaking relatively fast, meaning that they ran their analysis day-in – day-out with a significant “leak” in all their systems. The methods used, did not exceed 220C, and up to this temp., the columns were stable, which is interesting.

Initially one would say: that’s asking for problems. The question is: if a seal leaks, what will be the impact? Such a leak will act as a primary septum/seal-purge. Additionally there will be a second flow passing below the seal as the “real” septum/seal-purge.. Any air that diffuses back, will be swept away.

Is it safe to say that a leaking septum or microseal is not as bad as it may seem?

Further reading: seals for Agilent GC