Dear Sir/Madam:

My name is Ana Belen and I am a student of Chemical Engineering.
Actually I am working in my degree dissertation, which subject is :
Recovery and
Purification of sugar fatty acid ester produced through enzymatic
esterification. The reagents involved in the reaction are: methyl-
glucoside and stearic or oleic acid as acyl donor.
I have found two articles about a purification technique based on a
liquid chromatography on silica gel 60(200-400 mesh) to separate the sugar esters from
the rest of the products of the enzymatic synthesis (fatty acids,
diesters..). The articles mentioned above are:
-"Recovery of fructose laurate produced through enzymatic esterification" published in Separation and Purification Technology 19 (2000)p 229-236
- "Enzymatic Preparation of biosurfactants from sugar Alcohols and fatty acids in organic media under reduced pressure" published in Biotechnology and Bioengineering 48 (1995)p 214-221

The solvents suggested for the elution of the
differents fractions were: chloroform, chloroform/methanol, and
chloroform/methanol/water.
First, chloroform is used to remove the fatty acid, then
chloroform/methanol (90/10 v/v) to removed the diesters formed during
the esterification, and finally chloroform/methanol/water(64/10/1 v/v/v) is used to collect the desired monoester (methylglucoside stearate or oleate)
As you have a large experience in chromathography,I am writting to you
to ask for some information about this item, for instance, the method
in which the separation of ester is based (affinity....),the
equipment used in these kind of separations, as well as the conditions for the separation.
If you have some question about the proyect I am working in, you can
contact
my supervisor Eva Maria del Amor Villa, of the department of Chemical
Engineering in Dortmund University:
>
> delamor@ct.uni-dortmund.de
>
>
>
> Thanking you in advance
>
> Ana Belen

This forum is not meant to help you EARN your degree. You have all the research papers to do the work you need. Have you tried the separation yet? Don't be scared just do it.

We can't hold your hand. How are you going to function after school if you can't think or do things for yourself.

Anonymous,that was harsh. If you couldn't/wouldn't help, just be silent, as well as nameless. Ana's request was no less reasonable than most on this forum. Given that the request was well explained it deserves a courteous and thoughtful answer, if anyone has an answer. As most of us well know, chemical engineers have analytical chemists at their disposal to answer these questions after they graduate.

Ana,
I presume you want to separate these compounds on a preparative scale. I don't have experience with the methods you referenced, and probably no one else does either. So, you will just have to try it. I expect you do not have equipment for a high pressure chromatography separation. If you use the methods you referenced you will need some way to determine the composition of the fractions collected after separation. The esters of sugars esterified with smaller acids can be readily separated by reversed phase chromatography. You might use this technique, or thin layer chromatography, to check the pruity of your fractions.

Hi Ana,

It looks like you are going to do standard prep. column chromatography. The solvent order seems to make sense based on the order of elution you describe using the respective solvents. What I would recommend is to first work out some tlc conditions on silica tlc plates so that you can follow the progress of your prep. chromatography. You will understand as you read on.

Don't use your whole sample on your first try. You don't want to loose it all. Split off a small portion of your sample and try the chromatography on a small scale.

Now, when you run your packed column, don't collect all of your effluent in one shot (one fraction per solvent). Set up a bunch test tubes and collect fractions as you are doing the chromatography. You will end up with quite a bit of tubes when you are done. Now, using capillaries, take a sample of every second or fifth tube, depending on the number of tubes you have, and spike them across the bottom of a tlc plate. Develop the plate as per the chromatography conditions you established above. This will tell you what is in what tube. You can the combine the tubes of collected eluent, which contain the desired product and evaporate off the solvent. In doing this you will gain experience in your particular project and then you will be able to modify the technique.

If you need advice in packing a column and loading the sample and running the chromatography, please post and I can forward some useful tips and tricks. I assume this is a glass column. If so, please accurately describe the column, e.g. does it have a fritt on the bottom or just a valve.

Also see: Chromatography Forum: LC Message Board: TLC
By Anonymous on Wednesday, April 10, 2002 - 11:21 am:


To the first anonymous. You can not learn technique from a textbook our lecture. The most valuable skills I leaned as an industrial chemist where those "passed on from generation to generation", somewhat like mentoring. I am sure many of the skills you have today were learned by people showing you things or by you asking. How else does a "trade" get passed down?

I posted the first anon message to Ana.
I want to apologize for my harshness. I am just tired of this forum being a place for students to get answers without doing work for themselves.

It seemed that Ana already had the references she needed to start her experiments.

Please accept my apologies and best wishes with your experiments and future life as a chemist.