differential capacitance in chromatography

Differential capacitance (per unit area of interphase or electrode; SI unit F m −2) is given by
C = ( ∂ Q ∂ E ) T , p , μ i , ...
where E is the potential of the electrode with respect to a reference electrode, μ i is a set of chemical potentials which are held constant, T is the thermodynamic temperature, Q is the electric charge (per unit area of interphase or electrode), and p is the pressure.
PAC, 1974, 37, 499 (Electrochemical nomenclature) on page 509
PAC, 1983, 55, 1251 (Interphases in systems of conducting phases (Provisional)) on page 1261