Sepax HILIC Columns

[hajdaei]

We have an application coming up for which we are considering using a HILIC column. I won't go into a lot of detail (since I'm not asking for method development help) but the molecules are non-ionizable.

I recently got some literature from a company called Sepax. They offer several HILIC phases. There is also Waters Atlantis HILIC and Phenomenex has a HILIC column.

Does anyone have any experience with the Sepax column - or any of these for that matter. I'm considering Sepax because they come in a more convenient variety of column diameters and particle diameters.

Any suggestions would be much appreciated.

Thank You

[Uwe Neue]

hmmh... The Atlantis HILIC silica columns come in 2, 3, 5, 10, 15 and 25 cm length, 1, 2.1, 3, 4.6, 19 and 30 mm diameters and 3.5 and 5 mm particle size. What specifically were you missing?

[lmh]

Phenomenex also do a wide range of sizes and shapes.

But do be a bit careful of getting into HILIC. Most HILIC methods are totally dependent on acetonitrile, with no possibility of substituting any other solvent, which in the current situation could be bad.

[Uwe Neue]

I do not think that one needs acetonitrile that badly. I did my first HILIC separations in 1973, and we did not use acetonitrile back then. Mixtures of water, methanol, and solvents such as ethylacetate will do equally well. The primary retention mechanism in HILIC is a partitioning of the analyte into a surface layer of water.

[hajdaei]

Uwe: Smaller particles sizes would be good. In HILIC the back pressure is somewhat lower, so it's a good opportunity to take advantage of a particle size like 2.5 or 2.2 um.

Does anyone have any experience with the performance of any of these columns. It doesn't seem like there is any uniformity in HILIC. Every manufacturer offers a completely different type of column.

[Bryan Evans]

What type of compounds will you be analyzing?
I can post data on here if you can give more detail.

[hajdaei]

Bryan: The API is benzoyl peroxide.

Uwe: Could you elaborate on your post. Are you saying that you were not able to use pure methanol as the organic solvent, but that methanol with some percentage of ethyl acetate worked.

Thanks

[Uwe Neue]

Well, I am not that sure any more what I did in 1973... The subject was sugar separations with the same techniques that we call today HILIC. I worked with ternary solvent systems that consisted out of water methanol, and a water-immiscible solvent. I am sure I used ethylacetate and methylene chloride, but I am not sure what other crazy mixes I used. It has been a while, you know...

[tom jupille]

Does anyone have any experience with the performance of any of these columns. It doesn't seem like there is any uniformity in HILIC. Every manufacturer offers a completely different type of column.

Which is not all that different from the situation in reversed-phase HPLC. The HILIC retention mechanism is generally regarded as "mostly" liquid-liquid partition, but secondary interactions with the underlying column packing play a significant role. I would not expect the same behavior from a diol column as from an amino as from a zwitterion as from bare silica as from . . .

[lmh]

I'd be really interested in any non-acetonitrile mixes that work. I've only tried amino columns and Phenomenex's diol-based hilic, and both are a disaster if I mix even a tiny proportion of methanol in the otherwise pure acetonitrile organic. But I've never tried pure silica. I just assumed, particularly with the diol column, that hydrogen bonding is probably an important part of the water's sticking to the column, and since methanol can also hydrogen bond, there's less chance of getting two properly separate phases, water on the column and methanol in the mobile part. That set me looking for non-hydrogen-bonding solvents that are miscible with water, and knowing no chemistry, I couldn't think of any. Phenomenex were also deeply negative about any solvent but ACN, but of course I don't know what they've tried.

[Bryan Evans]

Hajdaei - I'm sorry, no data for benzoly peroxide

For the discussion of different solvents other than acn:

The data below shows saccharide separation on Unison UK-Amino.
Different solvents (such as THF & acetone) are compared to
acetonitrile:

http://www.imtakt.com/TecInfo/TI455E.pdf
http://www.imtakt.com/TecInfo/TI478E.pdf

Different elution order is obtained for some of the compounds.

[HW Mueller]

On the original question: I have used and compared only silica (Atlantis) and a zwitter ionic (ZIC-HILIC) column. They gave similar results on an amino acid as well as some "simple" radioactive ions like 22Na+, some results were quite different (if memory doesn´t play tricks it was 36Cl-).
(So, obviously, if the mechanism involves a H2O layer this layer is modified/influenced by the column´s surface, or there is interaction with this surface as Tom stated).
Anyway, even though my experience is limited to two columns I think it could be prudent, in absence of unequivocal published results, to start HILIC with a silica column.

[lmh]

Thanks all! Much appreciated.

[CaliHPLCuser]

[b]Sepax HILIC info...
http://www.sepax-tech.com/HILIC.php

Down to 1.8um Analytical/Prep 120, 300A, etc...
[/b]

[/b]