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Posted: Thu Oct 09, 2008 5:58 am
by LC_Master
I just want to mention that HILIC is meant for retaining extremely polar compounds. It's works beautifully, but the drawback is that HILIC is fickle. You must get the pH exactly right.
I would go further to say first try Reverse phase, then try a PFP, and finally try a HILIC column in reference to the previous comment.
Posted: Thu Oct 09, 2008 6:29 am
by Einar Ponten
The fact that HILIC is suitable for "highly hydrophilic molecules" or "extremely polar compounds" is more of a feature than disadvantage... To quote LC_Master; "You must get the pH exactly right" seems to be problematic.
However, this is not true since optimising mobile phase pH is a nice way to modulate the selectivity by controlling analyte hydrophilicity.
Refering to the long list of phases by XL; Could it be that just being "a polar stationary phase" does not mean it is really suitable for HILIC? Should it then be denoted "HILIC column"?
Posted: Thu Oct 09, 2008 7:07 am
by XL
First off, I need to clarify that the "reversed-phase and ion-exchange mixed-mode phases" I wrote in my previous post was meant to be "reversed phase/ion-exchange mixed-mode phases." More information can be found in the following links. All three Acclaim Mixed-Mode columns (WAX-1, WCX-1 and HILIC-1) can be used in HILIC mode in addition to other capabilities:
Mentioned without examples (which I can provide upon request) in
http://www.dionex.com/en-us/webdocs/488 ... 021407.pdf
Figure 8 in
http://www.dionex.com/en-us/webdocs/658 ... PN2024.pdf
Figire 5 in
http://www.dionex.com/en-us/webdocs/618 ... PN1963.pdf
In case I didn't make it clear, here is my point: all stationary phases that have
hydrophilic surfaces can be used in HILIC mode, such as the long list (rather than a single phase) that I gave in my previous post.
Posted: Thu Oct 09, 2008 3:09 pm
by Bryan Evans
An alternative choice to a HILIC column is Unison UK-Amino.
Molecular interaction occurs via normal phase / anion exchange:
http://www.silvertonesciences.com/files/TI316E.pdf
Posted: Thu Oct 16, 2008 11:57 pm
by Einar Ponten
...and what is the advantage/disadvantage?
Posted: Mon Oct 20, 2008 1:12 pm
by Bryan Evans
In terms of advantages of Unison UK-Amino as it relates to HILIC columns:
- NH2 phase allows for improved peak shape for reducing sugars
- Elution order can be different when compared to HILIC
Take for example for melamine and cyanuric acid,
under similar conditions the elution order is:
HILIC
1. cyanuric acid
2. melamine
Unison UK-Amino
1. melamine
2. cyanuric acid
So Unison UK-Amino is a nice alternative to HILIC phases.