Page 140 - Applied Pharmacognosy
P. 140
Mobile Phase Selection
How to adjust the Mobile phase Strength?
pH of Eluent and Retention of Ionic Solutes
The acid dissociation constant (pKa) of benzoic acid is 4.8.
COOH
Acidic
Increased
hydrophobicity
pH of eluent
Anionic
COO
Alkaline Increased
hydrophilicity
H+
The opposite occurs with basic (cationic) substances. 139
