Ester distribution on HPLC

[LaRKiN]

Hi everyone;

I have a question about ester distribution anaysis .
We synthesizing Glycerin oleate with gliycerin and oleic acid.We need to analysis mono di and tri ester distribution .

we have HPLC with IR and UV dedector and C18 column and GPC THF column.How we can make this anaysis? What sholud be analysis conditions?

Thank you in advance for helping !!!

[Consumer Products Guy]

Well, I'd do by high-temperature capillary GC, on a specialty metal capillary.

I'd dissolve in DMF or pyridine, make trimetyl silyl derivatives (the triglycerides will not derivatize but the glycerin, the mono, and di will). Program to like 370C and hold there a while.

HPLC won't give as much information, but we've used RP with ACN-ethanol and an ELSD detector.

[LaRKiN]

Thank you for responding ...

Unfortunately, we dont have ELSD dedector.

We obtained good chromatogram from reaction of glycerin and oleic acid with RI dedector and ACN/Acetone as a mobile phase.
But we didn't obtained any result from reaction oil acid and triethanol amine with same conditions.

Now, We are going to try with PLgel column and THF/Hexan...

Maybe it works...

[gapeev]

It can be and has been done. Here is a link to an application note:
http://www.dionex.com/en-us/webdocs/738 ... 266-02.pdf

Not sure about mono-, I do recall doing something very similar; di- and tri-glycerine esters showed reasonable behavior using ACN-water on a regular C18 column with APCI-MS. Had to start with some ACN.

The main issue is with the detection: UV is blind to these analytes and RI and ELSD are not very sensitive either. To compensate for that you would need to load more, this in turn will necessitate water-less mobile phases, this will drive you out of conventional HPLC space and you'll get a horrible headache with even rudimentary validation once you start seeing some peaks.

Even the simplest GC, the kind undegrad chemistry labs have in pretty much every college, equipped DB-1 or 5 column would be a much better tool. Might be worth asking around. Truly yours would be happy to talk with you.