Old column bleeds on transfer to new inlet

[laplynn]

Hello
I wonder if anyone has experience with an old column that bleeds extensively after change of inlet? I am using a column TG5-MS that has been previously used for PyGCMS analyses, consecutively 4 years, up to a T ramp of 210degC and occasional bake-out till 250degC. This column has a max T of 330degC/350degC. After changing to the next available inlet, performed column conditioning and purging, as well as an overnight bakeout, the bleeding remains high, such that my hexadecane injection standard of 140ppm remains undetected. Do you have a solution on what I can try? Thank you very much.
Lynn

[Peter Apps]

Welcome to the forum.

Pyrolysis HC often puts heavy muck onto the column that subsequently bleeds off. If you can tell which was the inlet end of the column when it was used for pyrolysis, then cut 1 m off that end and re-install. If you cannot tell which was the inlet end, then cut 1 m off both ends.

Peter

[laplynn]

Thank you so much, peter. I will go try it.