Page 127 - Applied Pharmacognosy

Mobile Phase Selection

Reversed Phase

❑ St. Phase: Octadecyl C18-bonded silica gel (ODS) (Non-polar).
❑ It can be also C8 (octyl) type or C4 (butyl) type.
❑ Mobile Phase; Water, methanol, acetonitrile.
❑ Separation will depend on hydrophobic interactions with non-

polar solutes.

Si CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2
-O-Si CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH3
C18 (ODS)
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