Chromatography Forum

Coworker is running the CDC cyanide method on a 7890/5975C. It has a Gerstel headspace autosampler attached and uses a cryotrap.

GC Method: Initial temp = 130 (hold 10 min), ramp 50 degrees to 250 (hold 5 min)

He is having problems with the Plot Q column breaking mid-run. This last time it broke off at about 1.5m from the GC inlet end.

Does anybody have any idea what would cause this column to break? It is a new column and the last one they had installed did they same thing?
Thanks!

I can say it broke just because of mechanical reasons: installation or before that (mishandling can lead to small cracks).
Luckily, the break is only 1.5 m from the inlet, you just discard the 1.5m broken piece and install the remain column to the inlet (1.5 m shorter).

If the poly amide coating and or column gets scratched during instalation the column can snap. Be extra careful when threading the column through the cryo trap. Do you have the Gerstel cryo as well? Mounted on the top of the oven? Check that there are no sharp edges on the cryo trap, and install the column so it is "relaxed" ( can't think of a better way to say it) so there is no strain on the column going through the cryo.
We have 2 styles of cryo traps, do the CDC cyanide and have never had a column break.

Thanks! Big Bear - it seems that the analyst keeps getting a large peak at the beginning of their run with ions 28 and 32m/z (N2 and O2). Is this something that you typically see when running CN?

PLOT columns are pretty fragile, at least in my experience more than normal capillary fused silica columns, and more prone to cracking/breaking. Gas peaks for nitrogen and oxygen would seem to be indicative of a leak which could be caused by a crack.