Traditionally columns of either 4.6 or 4.0 mm internal diameter (i.d.) and 150 or 250 mm length have been used as the industry’s standard for analytical applications. Such columns are still the most popular although there is an on-going shift to shorter and narrower i.d. columns.

Silica :

Silica is the most popular base material for HPLC phases. Despite its necessary porosity it has a high physical strength and a surface to which a broad range of ligands can be attached using well established silanisation technology. The majority of separations are performed using these bonded materials under reversed-phase conditions.
Today most silicas are spherical in shape. They are easier to pack into columns than irregular silicas. High performance, stable and low back pressure columns can be reproducibly achieved.
Organic polymer, alumina, titania, zirconia and graphitised carbon phases are also available from us. 

Guard Cartridge Columns:

Our universal guard cartridge system is recommended for use with analytical columns.

Optimum Flow:

A flow rate of 0.76 ml/min through a 4.0 mm i.d. column gives the same relative flow rate as 1 ml/min through a 4.6 mm i.d. column.

Performance:

The efficiency of a column depends on the choice of particle size and column length. The mode and quality of manufacture will also affect its performance.
Particle size refers to the average diameter of the spherical silica particle. Commonly used silicas have a distribution of diameters. Hence a material of nominal particle size 5μm can typically contain silica particles between 4.0 and 6.5 μm diameter
Smaller particles give higher efficiencies for constant column length. However at the same time column back pressure increases significantly resulting in an effective maximum column length.
The pore size of a silica particle determines the retentivity and capacity characteristics.