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.

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Ordering information

Product name	Packing Size	Code No.
COSMOSIL^® 40C₁₈-PREP	100g	37932-86
	500g	37932-15
	1kg	37932-31
COSMOSIL^® 75C₁₈-PREP	100g	37933-76
	500g	37933-05
	1kg	37933-21
COSMOSIL^® 140C₁₈-PREP	100g	37934-66
	500g	37934-95
	1kg	37934-11