Factors Affecting the Performance of C18 HPLC Columns

Physical properties of the chromatographic column could affect the performance of C18 HPLC columns.

Performance factors of C18 HPLC columns:

1. Silica gel purity
Class A silica gel has high residual silica hydroxyl with a negative charge and high metal content on the acidic surface, which leads to trailing of alkaline compounds.
Due to the low metal content and high silica hydroxyl pKa of class B silica gel, tail dragging of alkaline compounds does not occur.

2. Column size
Short column – short running time, low column pressure
Long column – high resolution, long running time
Narrow diameter column – detector has high sensitivity

3. Particle shape and size
When the mobile phase with high viscosity is used, the spherical particles can reduce the column pressure and prolong the life of the column. Smaller particles have higher column efficiency but can cause column pressure to be too high.

4. Surface area and aperture
The high surface area has strong retention capacity, column capacity and separation degree for separating multi-component samples. Low surface area fillers usually reach equilibrium quickly and are particularly important for gradient leaching.