FAME analysis using GC-FID

[newbie2010]

Hi, I’m analysing FAME’s in food. I have been given a good prep method and using this method I’ve just finished running the standards through the GC which all seemed to go smoothly. When running a test sample with known values I’m finding that the saturated and monounsaturated levels seem ok but the polyunsaturated FA’s seem to be low. I’ve tried preparing the samples again to no avail but as I’m new to GC work I was wondering if there was something I was overlooking .

Thanks
Louise

[JGK]

You're overlooking the fact that we're not clairvoyant for a start.

Without a basic descrption of the sample preparation method we can't help you.

Also what type of sample is your test sample?

[skunked_once]

As JGK replied, we need more information.

I’m finding that the saturated and monounsaturated levels seem ok but the polyunsaturated FA’s seem to be low.

Are you trying to quantify the exact amounts of each fatty acid or are you looking for relative percent amounts of each? Please explain in more detail what you have tried and what you are hoping to do.

[chromatographer1]

Poly unsaturated FAs are quite unstable unlike the monoolefins and saturated FAs.

Your method of esterification has a great effect on errors that can reduce the yield of the polyunsaturates.

Sadly, we have no idea how you are preparing them.

Sadly, you will not have any advice that will help you.

Good luck,

Rod