By Anonymous on Tuesday, October 21, 2003 - 06:46 am:
I am testing the Bonus-RP phase for my methods and have noticed that I get more retention from the Bonus-RP than the Discovery (for equal conditions).
Has anyone any other comments when switching between the two?
The Discovery is C16 and the Bonus-RP is C14.
David
By Uwe Neue on Wednesday, October 22, 2003 - 03:44 pm:
What are your compounds? Acids? Bases? Neutrals? Everything?
By Anonymous on Thursday, October 23, 2003 - 12:31 am:
Uwe,
They are benzoic and sorbic acid with 0.1%TFA and MeCN.
David
By Uwe Neue on Thursday, October 23, 2003 - 02:43 pm:
David,
The Bonus RP is prepared in a two step process and contains large amounts of amine on the surface. On the DiscoveryAmide C16, we have not found any amine. It is probably prepared in a 1-step process.
Uwe
By Anonymous on Friday, October 24, 2003 - 12:58 am:
Uwe,
That is interesting.
It is of great advantage too on one of my other separations - where I can now get away with an isocratic run (thus saving time on re-equilibration after the gradient).
I am using a 3.5um instead of my 5um Discovery and the time savings there are significant.
When will the 1.8um RP-Bonus be out in the shops!!!
David
By Bob Ziegler on Friday, October 24, 2003 - 04:11 pm:
Your conditions suggest you are trying to resolve these in a reversed phase mode. The separation is primarily based on the hydrophobic properties of the columns and the sample. A likely explanation for the longer retention of the Bonus RP is that it is on an 80Å pore size silica. The Discovery is on 180Å silica. With the larger pore size, you don't get as much ligand bonding, and, therefore, it has less hydrophobic character. Even though it's C16 vs. C14, there will be less "carbon load".
By A.Mouse on Saturday, October 25, 2003 - 07:34 pm:
Pore size, pore volume, ligand length, derivatization are all different. Tough to tell what is the important factor. Considering the mobile phase and the pH, I don't think that the amine will play a role.