L1 /
12
CH3041
HPLC II
Only about 15% of all chemicals can exist
in the vapour phase and so LC techniques
have a big role to play. (eg. TLC, HPLC)
in the vapour phase and so LC techniques
have a big role to play. (eg. TLC, HPLC)
• Separations rely on the polarity differences of the
components and their affinity for the
organic surface of the stationary phase.
organic surface of the stationary phase.
• Most HPLC columns (3mm, 30cm) are reverse
phase columns : the SP is less polar
than the MP. (eg. hydrocarbon bound to
silica)
• For use at pH < 7 the SP is octadecylsilane ODS on
5mm silica spheres: C18-silica.
• For pH > 7 polystyrene/divinylbenzene
macroporous
copolymer spheres are used.
• Hybrid
columns: pH 1-12, C18 - CH3-silica
