Chromatography Forum

What is the difference between vespel and graphite ferrule. And can I use graphite as inlet ferrule to MSD column and MSD interface?

Hello

There is a lot of materials available on manufacturers websites...
For example see links below:

http://www.bioszeparacio.hu/_user/brows ... errule.pdf

https://www.sepscience.com/Techniques/G ... c-Ferrules

Regards

Tomasz Kubowicz

Vespel is hard and graphite is soft.

Mixtures of graphite and vespel have intermediate hardness/softness.

Grahpite ferrules deform very easily and shed particles that conduct electricity - these are bad news in a mass spec, so do not use graphite ferrules on the MS end of the column.

Peter

As Peter said, you should only use the graphite/vespel mixed or vespel ferrules on the MSD interface, the 100% graphite will leak and can contaminate the ion source. Vespel and graphite/vespel ferrules do shrink when heated, so you will need to retighten the fitting a day or two after installing, or keep a few ferrules in the oven in a beaker so the heating of the oven will pre-shrink them before use.

100% graphite is ok for the column inlet/injector end of the column. If you will be doing maintenance such as trimming the column on a daily basis, then graphite is the best choice since it doesn't adhere to the column and is removed and reinserted easily. Just be certain that you always trim about 1cm of column from the end AFTER you put the ferrule on the column to be sure you remove any pieces of graphite that might scrape off the ferrule as the column passes through it.

I can confirm that what the posters above me said is also common practice in our lab.

Graphite or mixed vespel/graphite (=VG) for inlet, and VG for the MSD end. I can add that we prefer to use relatively larger (longer) ferrules for the MSD end, since in our experience air leaks happen more often with the smaller ones.