Chromatography Forum

I am a researcher from Spain, my name is Cristina. At this moment, I am extracting inulin and olygosacchrides from Jerusalem Artichoke. I am looking for a method for separation of olygosaccharides (glucosa-n fructose) with different length chain. I want to know if is possible analyze and separation without use the detection for amperometric pulse.

Is it posible with a method of chromatography liquid with other detector, for example Refraction Index or DAD?

Thank you for you attention.

If your compounds are at a higher enough concentration then certainly RID may be the way to go. there are lots of specialised HPLC applications for sugars. Try a "Google" scholar search... you should literally find 1000's of hits...

Refractive index detection should be fine. If you have a water-wettable C18 column, you can run this with straight water as the mobile phase. I ran this on Resolve C18 in the late 1970's. Worked like a charm...

Thank you for your answers.
Every hits I have found use amperometric pulse to detect olygosaccharides with diferent chain length (glucosa-n fructose)
The column I have is a Shodex KS-802 and using water as the only mobile phase I can only separate until n=3, and every fructooligosaccharydes with a chain longer than 3 are detected in an unic and very wide peak.

Somebody told me it would be necessary to use a gradient method to get defined peaks of these compounds, but I don't Know if it is possible with this column and with the RI or DAD detectors.

What kind of column I must use to distinguish in different peaks the compounds from n=4?

Thank you for your attention

With RI detection, gradients are pretty much out. Try BioRad for more examples of CHO separations.

http://www.metachem.com/Products/Column ... bindex.htm

With a plain water mobile phase, you can use evaporative light scattering detection.

You might want to try Alltech's (www.alltechweb.com) Prevail Carbohydrate Column. It works well with sugar oligomers and has the ability to run a normal phase gradient with water and acetonitrile. You will need an ELSD for this. If you can use some chemistry, it may be possible to tag the reducing end of these polysaccharides with a chromophore. Then the DAD would work with this column as well.

I have also separated Inulin on Polymer Labs (www.polymerlabs.com) Aquagel-OH columns. Using two Aquagel-OH columns (30 and 40) in series I get an excellent peak for the Inulin when n=37. I am using ELSD for detection and 50 mM Ammonium Formate at pH 9. I know you are looking at much shorter chains of Inulin. Because these columns separate purely on size, it may be the short chains will retain longer and separate from the other chain lengths. Maybe PL can help you out. PL also has a Sugars column that may work.

Good luck.