C18 under 100% water phase? No problem!

July 11, 2019

C18 is retentive to non-polar compounds as the non-polarity of C18 group, but for polar compounds, sometimes the mobile phase with high water ratio should be used to make the analyte retained on the column. However, under this condition for a long time, phase collapse will occur on conventional C18, which will gradually weaken the force between the stationary phase and the mobile phase and shorten the retention time of compounds.

To solve this problem, Welch has developed unique bonding technologies: Ultisil AQ-C18, Ultisil LP-C18, Ultisil Polar-RP and Ultisil ALK-C18, which have excellent ability to withstand high proportion of water phase and maintain long service life of the chromatographic column.

Ultisil AQ-C18

Ultisil AQ-C18 column is designed to use at 100% water, which has a good compatibility with high proportion of water phase.

Features:

· Ultra-pure spherical porous Type B silica, purity> 99.999%

· Carbon Loading: 12%, Pore Size: 120 Å, Particle Size: 3μm、5μm、10μm

· Less retentive than XB-C18 for non-polar compounds

· Increased retention for polar and water-soluble compounds

Ribavirin(EP 9.0)

Ultisil LP-C18

LP phase consists of two very bulky hydrophobic protective groups to prevent siloxane bond from hydrolysis at low pH condition. Because it is not endcapped, selectivity will not be changed due to the easy hydrolysis of the endcapping reagent under acidic conditions.

Features:

· Not endcapped, prevents siloxane bond from hydrolysis at low pH condition.

· Compatible with 100% water and 100% organic phase

· Strong steric selectivity

· Suitable for samples which can’t be separated on conventional C18, could obtain ideal baseline noise with ELSD detector under strong acid conditions

Ultisil Polar-RP

A polar functional group close to the surface is embedded into C18 chain, increases the wet ability of this phase, thus decreasing phase collapse, making this phase compatible with mobile phase of up to 95% water content. The polar functional group also shields the effects of unreacted silanol groups, providing excellent peak shape for very polar and strong basic compounds and different selectivity than C18 phase.

Features:

· Excellent at 100% water content in mobile phase

· Different selectivity to other C18s

· Be retentive for polar compounds.

Amoxicillin and clavulanate potassium