Reversed phase liquid chromatography has been widely used due to
its separation characteristics, high theoretical plate number,
reliable reproducibility and ease of use.
However high performance large-scale columns for preparation and
purification are very expensive and many chromatographers need
less expensive preparation and purification techniques.
The particle sizes that are most generally used for analytical
separations have been 5 and 10µm. However many large scale
separations don't require such a small particle size and 40 or 140µm
sized packing material is sufficient for large scale separations.
The COSMOSIL C18-PREP is
a conventional C18 packing
material based on totally porous spherical silica, which can be
effectively used for medium pressure and open column
chromatography. There are three different particle sizes, as
outlined in the table below.
Material characteristics
40C18-PREP
75C18-PREP
140C18-PREP
Silica gel
totally porous spherical silica
Average particle size
40 µm
75 µm
140 µm
Average pore size
approx. 120Å
Specific surface area
approx. 300m2/g
Stationary phase
octadecyl group
End capping treatment
near-perfect treatment
Carbon content
approx. 19%
Application
flash column chromatography
flash or open
column chromatography
Particle size, flow rate and theoretical
plate number
Because reversed phase chromatography employs effluents of high
viscosity such as methanol and water, the flow rate is lower than
that of normal phase chromatography which uses effluents of low
viscosity such as hexane and ethyl acetate.
