Septa

[dtanner]

As a novice to the chromatography world could someone help me out?
When/why is it advantageous to use a silicone/teflon septa?
(other than the obvious of retaining the sample)
Why can't we just use a plain teflon septa?

Thanks,
Doug

[Bernd]

As a novice to the chromatography world could someone help me out?
When/why is it advantageous to use a silicone/teflon septa?
(other than the obvious of retaining the sample)
Why can't we just use a plain teflon septa?

Thanks,
Doug

Hello Dtanner,

silicon rubber is the most common matrial for septa because of the good mechanical and temperature properties. For special samples a teflon layer (in injector direction) is in use.
Plain teflon is to hard so the syringe needle is damaged during the first shoot. BTW, max temperature of silicon rubber septa: 250 to 300°C, teflon only 230 than it vaporize monomers to the injector...

rgds
Bernd

[Bas]

Also the silicone has good reseal properties avoiding carrier gas leakage.

Cheers
Bas