logk slope (S=4 or B=10)

Discussions about HPLC, CE, TLC, SFC, and other "liquid phase" separation techniques.

2 posts Page 1 of 1
Hi,

Kind of confused here. I've been quite familiar with tenets of LSS model and Snyder's logk' linear relationship with solvent volume fraction. It is commonly accepted that S=4 for small molecules.
However, when browsing Neue's classic papers on modelling peak capacity from a decade ago I came across his version of this relationship where the same slope (called here B and seemingly defined in the same way as S) according to Neue is typically 10 for small molecules.
Am I missing something fundamental here?
Is it the same thing that S or something entirely different, hence different typical value for small molecules?
This vale of 10 is kind of critical for Neue's peak capacity formula to show sensible results.

I'd appreciate any comments!


(...) the slope B of the relationship of the logarithm of the retention
factor and the solvent composition. For small molecules, the
value of B is about 10 (if the solvent concentration is expressed
as the volume fraction).(...)
Journal of Chromatography A, 1079 (2005) 153–161
Answering myself after a while. It appears Neue's model was based on natural logarithm and the version used today in gradient equations is decimal log, so 2.3x difference. This should explain the 'typical' B v S.

Cheers
2 posts Page 1 of 1

Who is online

In total there are 14 users online :: 2 registered, 0 hidden and 12 guests (based on users active over the past 5 minutes)
Most users ever online was 200 on Fri Nov 10, 2017 4:15 pm

Users browsing this forum: Baidu [Spider], Google [Bot] and 12 guests