Chromatography Forum

Patrik,
you can repeat some simple experiments that will show that your ZIC-HILIC is in your group
" Charged - strong electrostatic interactions
Plain silica phases, aminopropyl phases":

See if you can elute a positively charged entity (as much as micro mols) with a mobile phase consisting of 0.00001M strong aqu. base on your ZIC-HILIC.

Dear Hans,

ZIC®-HILIC Separation of Betaine from Chinese Lycium
http://www.sequant.com/sn/ufiles/SeQuan ... 00-30A.pdf
Mobile Phase (v/v): 75%, Methanol, 25%, Ammonium Acetate 10 mM, pH6
(total ionic strength 2.5 mM)

ZIC®-HILIC Separation of Choline and Inositol
http://www.sequant.com/sn/ufiles/SeQuan ... 00-40A.pdf
Mobile Phase (v/v): 80%, Acetonitrile, 20%, Ammonium Acetate 100 mM; pH 4.5
Overall ionic strength: 20 mM
The second example is at double the requested ionic strength, I know.

These are examples of positive entities eluted isocratically with reasonable retention factors (3-5) available at http://www.sequant.com/applications

Hans,

I don't know what the problem is...

I got perfect peak shapes for morphine and its glucuronide on Atlantis HILIC silica with 10 mM ammoniumformate, pH 3. The separation was done with a gradient on a 5 cm column, and there was so much space between the two peaks that you could put several HPLC instruments between them.

Lessons:
1. You get good peak shapes for basic compounds with HILIC silica.
2. HILIC is a good technique for analyzing metabolites that are difficult to retain on a C18.

Again, I am not making any qualifying statements about silica in HILIC. I am just stating that I could not find a difference in silica interactions between ZIC-HILIC and Atlantis. If I remember correctly, I even stated above that under the same ammonium salt conditions for both columns you obliterate the SiO- interaction in both columns. Patrik´s and Uwe´examples nicely show this. I added the example of 0.00001 M base for the mobile phase under which one will not elute a positively charged ion from both columns.
My problem is how one can claim that ZIC-HILIC is unique in that it does not give SiO- interactions.