Can I use a metal column in OPTIC Inlet?
No, the OPTIC inlet is heated with a direct heating technique, this means that a current goes true the metal inlet tube here the liner is placed. If the inlet body is in contact with the chassis of the GC (electrical ground) it has a short cut and the performance is no longer normal.
When a metal column is installed in the OPTIC inlet usually a graphite ferrule is used. The graphite ferrule is not an isolator and current will go from the inlet to the column. The inlet heating performance is not optimal in this case and the current going from the inlet to the metal column will heat the column.
So if you want to use a metal column with OPTIC, please use a fused silica retention gap first and connect this to the metal column.