Date: 14-APRIL2020 Last Updated: 11-OCTOBER-2025
Calculating Ligand Density for Cogent Columns
Ligand density is a key parameter that reflects how much bonded phase is present on the surface of the silica in an HPLC column. For Cogent columns, we calculate ligand density using the Berendsen-de Galan equation:
Where:α = Ligand density (µmol/m²)
- %C = Percent carbon content of the bonded phase
- MW₍carbon₎ = Molecular weight of carbon (12.01 g/mol)
- nC = Number of carbon atoms in the bonded ligand
- MW₍ligand₎ = Molecular weight of the bonded ligand (g/mol)
- SBET = Specific surface area of the silica (m²/g)
This equation accounts for the carbon contribution from the ligand and the silica surface area to estimate how densely the ligand is bonded.
Example:
Using this method, the Cogent UDC-Cholesterol™ stationary phase has a calculated ligand density of approximately 1.5 µmol/m², indicating a well-covered and stable bonded phase.
