KPF6

[Mattias]

Hi,

I was asked to set up a method with this chemical, potassium hexafluorophosphate. I never used it before and it has a MSDS longer than most.

The method is a regular RP-HPLC method and I cannot really see why it is being used. What are the benefits of this buffer?

[tkubowicz]

Hello

One of the LC method for basic compounds is to use chaotropic ion which can form neutral ion pair (hydrophylic in mobile phase). Common one is PF6-
As I remember the other one that works as well is ClO4-

Regards

Tomasz Kubowicz

[Mattias]

Hello

One of the LC method for basic compounds is to use chaotropic ion which can form neutral ion pair (hydrophylic in mobile phase). Common one is PF6-
As I remember the other one that works as well is ClO4-

Regards

Tomasz Kubowicz

Thanks Tomasz!

So it is a peak shape improver for basic compounds more or less

[mattmullaney]

And PF6- (a chaotropic agent, as per the Hofmeister series of chaotropic and kosmotropic agents) will also generally increase retention of polar analytes to a degree.

If you're interested, look up papers written by Kazakevich and LoBrutto such as:

"Reversed-phase high-performance liquid chromatography behavior of chaotropic counteranions", Journal of Chromatography A, Volume 1064, Issue 1, 28 January 2005, Pages 9-18, by Y.V. Kazakevich, R. LoBrutto and R. Vivilecchia.

and

"Effect of counter-anion concentration on retention in high-performance liquid chromatography of protonated basic analytes", Journal of Chromatography A, Volume 913, Issues 1–2, 13 April 2001, Pages 189-196, by R. LoBrutto, A. Jones and Y.V. Kazakevich.