Hello to all!!!

can anyone tell me what kind of column and mobile phase i can use for small residue peptides. or any chiral additives for my mobile phase that i can use on my regular reverse phase C18 column. I would like to see if any enantionmers present.

Thanks

L

Hi

as far as I know, there is no chiral additives that will make your typical C-18 column able to fully resolve a compound. With long column, 25cm long, you can be able to see a split peak but I never saw nothing close to a baseline resolution.

You're best bet is to buy a chiral column from one of the many producers. You might want to try the following address www.astecusa.com

Laura;

Perhaps you are asking too much from a C18 column. I do not think is possible to do enantiomer separation of small peptides by just adding something to the mobile phase. Cyclodextrins are perhaps the only additive that could do something for you.

A better approach is to use a Crownpak column. These have been designed for the chiral separation of amino acids and amines, and in some instances the separation of small petides is possible. Please consult my publication in Journal of High resolution Chromatography 14, 816-823 (1991). There have been also a number of CE publications that have reported similar separations.

Good Luck;

Benjamin Esquivel

Hi Laura,

I haven't right now anything in my mind but I wanted just mentioned that I'm not quite agree with the two previous replies. It should be chiral reagents, hydrophobic enough that could dymamically change the properties of your C18 column to a chiral one. However that will provide some enantioselectivy for a family of compounds, it does not garranty that it would be suitable for your compounds of interest. Obviously the reagent should not interfere in terms of detection with your analytes.

Furthermore, this type of column modification sometime modify your column properties for ever (in the same way some very hydrophobic ion-pairing reagents does).

Finally, I'll agree with the previous replies that it would be more elegant to go directly for a chiral column adapted in your problem (it may safe you a lot of time!).

Hope the above helps,

Kostas

PS: I do not have the reference in mind but some years ago (more than 5) there were a publication which used amino acid derivatives (the hydrophobic side chains tested were linear alkyl or naphtalene type) in order to modify the surface of porous graphitic carbon columns. The column could then separate underivatized amino acids and I think small peptides as well. I could try to dig it out if you are interesting