Chromatography Forum

Hi,

I am trying to analyze fame (gc-fid) with sp2380 (L×I.D. 30 m × 0.25 mm, df 0.20 μm) gc column. When the supelco 37-fame mix is analyzed, the separation between C18:1 trans & cis is perfect. But when I analyze olive oil, I cannot see the trans isomers. I tried higher split ratio, stable temperature at the time that these fame are observed, but with no success.

Any ideas?
Thank you for your time

Hi,

I am trying to analyze fame (gc-fid) with sp2380 (L×I.D. 30 m × 0.25 mm, df 0.20 μm) gc column. When the supelco 37-fame mix is analyzed, the separation between C18:1 trans & cis is perfect. But when I analyze olive oil, I cannot see the trans isomers. I tried higher split ratio, stable temperature at the time that these fame are observed, but with no success.

Any ideas?
Thank you for your time

First of all doe's your olive oil contain trans isomers ?
IMHO 30 m column is too short to get sufficient resolution for FAME analysis.

The olive oil that I analyzed is a reference material, so the compotitiion of fame is known. I selected this column because the chromatograph that the company provided, appeared to have perfect separation for the basic cis & trans isomers. It seems that the separation is not so good with matrix samples.
The column is recently purchased, so I am not able to buy a new one.
Do you think there is a way to achieve separation?

Thank you for your reply

I also wonder if your sample is low on trans C18:1

Have you tried to spike some of the reference sample with the trans isomer and see if it appears? If so, then maybe the reference concentration is misstated.