Chromatography Forum

Hi,
Some time ago I used to determine log D values using an HPLC method published in 2001 by Lombardo et.al. In my opinion, the method is robust and provides good log D (log P at pH=7.4) values. Unfortunately, I had to allocate this HPLC for something else. I was wondering if anyone had had similarly successful experiences using RP-TLC plates instead of HPLC? Most of the papers on this topic are limited in their scope and do not show correlations as good as the ones published by Lombardo. Does anyone have any practical experience with RP-TLC for Log D determinations?

No specific experience, but TLC in general is a very poor technique for getting at any equilibrium distribution coefficients because it operates under inherently disequilibrated conditions (i.e., the plate starts off dry and must equilibrate with the mobile phase as the chromatography progresses).