The ligand density can be calculated using the Berendsen-de Galan equation:

α = 106 %C/(102 MW carbon nC – %C MW ligandSBET

where α is the ligand density (µmol/m2), %C is the percent carbon (%), MW carbon is the molecular weight of carbon (g/mol), nC is the number of carbon atoms per bonded ligand, MW ligand is the molecular weight of the organic bonded ligand (g/mol), and SBET is the specific surface area of silica material (m2/g).

For example, the ligand density of the Cogent UDC-Cholesterol™ stationary phase comes out to approximately 1.5 µmol/musing this equation.