Hilic and sugars

[Valerie]

Hello,

I have heard a lot about new HILIC columns, like Sequant ZIC HILIC, Waters Atlantis HILIC silica...

As HILIC retention mechanism is used since years for Carbohydrates and Sugars separations, with silica based NH2 columns, I don't understand why I can't find any application of sugars (even simple sugars : fructose, glucose, saccharose ...) on these new HILIC columns.

As NH2 column always show very bad lifetime, I think maybe unbonded phases like HILIC Silica or new generation columns like ZIC Hilic, could be a better choice for sugars applications (in LC - ELSD methods)...

Thank you for your experienced feedback !

Valerie

[Uwe Neue]

There is a second requirement for the HILIC separation of sugars: you need to work at alkaline pH. This is the reason why the common sugar column is an amino column.

However, not all of these columns are created equal. You should check out the Carbohydrate Analysis Column from Waters. It does not exhibit the large changes in retention observed with other amino columns.

[Patrik Appelblad]

Dear Valerie,
I agree with you, dedicated HILIC phases are much more suited for sugar applications than amino columns. Within short, SeQuant will be posting such applications on the web.

I quote Uwe:
"There is a second requirement for the HILIC separation of sugars: you need to work at alkaline pH. This is the reason why the common sugar column is an amino column. "

The need for a higher pH for certain applications, is one of the reasons why we developed a polymeric phase with the same functional group as for the silica version.

Please visit our www, and leave your contact details so that we can send you some of these new applications. We are currently reorganizing our web page wherefore newer applications are still not made public.

[Valerie]

Thank you for your inputs,

I have other questions : If the requirement for HILIC separation of sugars is alkaline pH, why do I see many application with only ACN : H2O (80:20) for columns such as carbohydrate Analysis from waters. Is this column a silica based or polymeric column ( I think it's silica)?

And what is special on The Waters Carbohydrate column to allow less changes in retention times?

Could you explain the effect of alkaline pH on simple sugars in HILIC retention mechanism ?

And for the Sequant ZIC HILIC column, what is the pH range of use for the polymeric column?

Thank you again

Valerie

[Uwe Neue]

The local environment on an amino column in acetonitrile water is basic (by local, I mean the pores).

I can not give you the tricks that makes the Waters Carbohydrate column work. There are too many competitors on this board who would love to figure out what to do to make a column like this.

the alkaline pH speeds up the conversion mechansim between the alpha and the beta form of the sugar, which can be separated chromatographically. You can find aout more in my book "HPLC Columns".

On the pH stability of the ZIC Hilic column, Patrick will be able to give you a better answer than I would.