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Re: calculation of triglyceride ammount to fatty acid methyl
Posted: Sun Feb 06, 2011 11:33 pm
by leo1352
I can not comment on how to improved the yield of your procedure as I do not have the details - all the steps and reagents.
I am using 3% Sulfuric acid in Isopropanol vol/vol heated up at 100C for 2 hours. The matrix is standard triglyceride cocktail.
Cheers
Re: calculation of triglyceride ammount to fatty acid methyl
Posted: Tue Feb 08, 2011 3:23 am
by Don_Hilton
From the information you give, I can make reccomendations of a few things to try:
You can try changing the length of time for derivitization. Be sure the isopropanol is as dry as you can get it. (The side reaction is hydrolysis of the esters - and if there is an appreciable quantitiy of water in the isopropanol, you will generate some free acid) Check the procedure for making the sulfuric acid in isopropanol.
Re: calculation of triglyceride ammount to fatty acid methyl
Posted: Wed Jul 13, 2011 4:29 pm
by Phycal
Why use IPA for this reaction? The steric properties of IPA might not give you good results.
I would use dry methanol instead - as the derivatized products are more stable.
Also, I assume you are exracting into another solvent - like chloroform or hexane. Make sure after extraction to put the sample through anhydrous sodium sulfate to dry it. It helps to keep the samples stable.
Re: calculation of triglyceride ammount to fatty acid methyl
Posted: Wed Jul 13, 2011 6:21 pm
by leo1352
Why use IPA for this reaction? The steric properties of IPA might not give you good results.
I would use dry methanol instead - as the derivatized products are more stable.
Also, I assume you are exracting into another solvent - like chloroform or hexane. Make sure after extraction to put the sample through anhydrous sodium sulfate to dry it. It helps to keep the samples stable.
I use IPA since Methyl esters are more volatile and I have experienced lower recovery.(Hexane). also I am mostly interested on Butryric acid which in a DB-225 column comes off early with solvent tail. I use GC-IRMS(have to keep the He back-flush open for 200S to avoid solvent to the reactor).
I am interested to know why IPA esters are less stable?