High temperature septum recommendation needed for GCMS

[Tony]

Hi,
We have a Thermo Trace GC 2000 fited with a SSL injector that we are running at 350°C. This high temperature is necessary to measure some high-boilers in our samples by GCMS. At the moment we are using Thermogreen LB-2 septa, which are rated to 350°C. However, we find that at any SSL temperature above 310°C, the septa start to melt and crumble at the injection point, resulting in a massive increase in bleed/background.
The disparity between the septum rating and what actually happens at the SSL set temperature may be because the Thermo SSLs are known to heat the liners more "evenly" than other brands. This means the septa are heated more. The septum rating then depends on what SSL it was tested on.
Regardless of the niceties of how the LB-2 was rated, we still need a better performing septum for our method. Can anyone recommend another brand of septum that will perform better than the LB2 at 350°? This has to be compatible with the Thermo SSL - i.e. 17mm diameter.

thanks
Tony

[CE Instruments]

The Thermogreen septa are about the best high temperature Septa for the Trace GC. The only other alternative is Septa BTO as supplied but these too melt. A compromise is to remove the top aluminium ring from the injection housing. This negates the "same temperature" over the whole injector benefits but does keep the septa cooler.
Make sure too that you fit the septa support ring the correct way up, ridges upwards. Avoid overtightening the injector as this stress forces Septa into the path of the needle allowing bits of septa to fall into the injector to cause the background peaks you are getting. Note if you are getting significant Septa peaks you have bits of septa in the injector. Cool your injector and remove the nut at the bottom to clean out the injector

[EnvironLab]

Maybe you could try a JADE inlet. I don't have any experience with them but they're supposedly rated to 400C. They are pretty expensive but are supposed to last a very long time. I'm also not sure whether they are compatible with all autosamplers.