Page 143 - Applied Pharmacognosy
P. 143
Mobile Phase Selection
Problems Encountered with Alkaline Eluents
❑ First Problem: Deterioration of packing material in alkaline
medium.
With alkaline eluents, although the
ionization of basic substances is
N N suppressed, and the retention
H
+ strength increases...
OH Si The pH for a standard ODS
O column should be kept
OH Si between 2-5
OH
OH …silica gel dissolves in
OH OH alkalis, so the packing
material deteriorates rapidly. 142
