GC method for vegetable oil and fame

[eddielepew]

Can anyone suggest a method for vegetable and fame using GC.

I want to be able to determine the quantities of fame within the sample of oil. Not all of the fatty acids will have been esterified and I want to know how much has.

Thankyou for any replies.

[Consumer Products Guy]

If you want help, please state clearly whether you are interested in the composition overall of the sample, or the composition of the free fatty acids, or the composition of the glycerine esters only.

[eddielepew]

Hi
I need to know the overall compostion of the sample. I want to be able to determine what percentage is fatty acids, glycerine esters and any other major constituents of the oil.

[Consumer Products Guy]

See AOCS Official Test Methods. Determine FFA by titration in hot neutral alcohol with sodium hydroxide titrant. Remainder will be triglycerides (glycerine esters). For free glycerine, use AOCS periodate titration or capillary GC after trimethylsilylation.

[chromatographer1]

It is easy to determine how much FAME is present in a mixture of esterified FA and glycerides and free acids.

Dissolve your sample into hexane or some other suitable solvent and inject onto your GC. Use an internal std to measure the FAMEs present. The Free acids and non-esterified components will remain on-column or in the injector port.

You may wish to calibrate your int std and FAMEs prior to injection of your sample.

You could also use HPLC to perform this analysis, or even TLC if qualitative results are adequate.