Chromatography Forum

Hi all,

I am strugling with high background peaks problem. I am currently suspecting the Viton O-ring I use for the GC inlet liner.

I am using Varian GC-MS, with 1177 Injector. I noticed that the O-ring became flat! I am using the Injector above 300 oC.

Do you think the Viton O-ring withstand such a high temperature?

I checked in the Agilent website for the Max temp for this O-ring but I failed to find a figure.

Any help in this regard is highly apprciated.

Thanks in advance.

Without knowing the supplier it is a little tough to get precise information but for generic Viton o-ring specs try: http://o-rings.com/pdf/TRV70875.pdf.

I have used these for a sealing application in a GC column oven. I found that they worked until I started running PBDE analysis with a 20 minute hold at ~320 degrees. They deformed enough to leak within a few hours. With a normal PCB analysis and only a short hold at that temperature they were good for weeks.

The vitons will deform at those temps, they just need to be replaced more often is all.

Agilent sells a graphite o-ring for 350 and above - I do not like to use them.

Thanks Steve and Yama,

I actually find the ring FLAT after using the high temperature above 300. But is there any possibility for bleeding to the injector ad then to the column?

Yama: what is the problem with the graphite O-rings?

I run with viton rings at 300 - they flatten out but maintain a seal - I do replace them every week or so - before they get ragged edges.

I don't like the graphite ones because careless operators tend to smear graphite around is all - they are pretty reliable otherwise.

I am a fan of the graphite o-rings - having had to peel the remains of a viton o-ring off the inlet too many times to please me.