"Christmas tree" effect

[Urry]

Dear colleagues,

Could you help me to overcome the “Christmas tree” effect I’ve got performing my GC/MS analyses. A sample injected usually consists of organic acid, amino acid and sugar TMS derivatives, pyridine and chloroform or acetonitrile instead of pyridine/chloroform. The injector (Optic) is programmed from 70 to 250 degrees, initial column (SPB50) temp is 70 degrees. After a number of runs I’ve started to observe the “Christmas tree” effect in peaks. The column replacement hasn’t helped.
Could anybody tell me what might be a reason of this effect and how to overcome it?

Thank you in advance,

Urry

[Bernd]

Hello Urry,

Chrismas tree is nice at the end of the year.. but not in chromatograms.
The reason why you see this may be in a to high injection speed, so that You get liquid drops on the stationary phase and in this way "multiinjections". Also the injection amount/ volume and the compatibility of solvent mixture and stationary ph. is important.
Try to control this values.

rgds

Bernd Mischke