If $$\mathit{\Gamma}_{i}^{\sigma}$$ and $$\mathit{\Gamma}_{1}^{\sigma}$$ are the @[email protected] concentrations of components i and 1, respectively, with reference to the same, but arbitrarily chosen, @[email protected], then the relative adsorption of component i with respect to component 1, is defined as $\mathit{\Gamma}_{i}^{\left(1\right)} = \mathit{\Gamma}_{i}^{\sigma}- \mathit{\Gamma}_{1}^{\sigma}\ \frac{c_{i}^{\alpha}- c_{i}^{\beta}}{c_{1}^{\alpha}- c_{1}^{\beta}}$ and is invariant to the location of the @[email protected] Alternatively, $$\mathit{\Gamma}_{i}^{\left(1\right)}$$ may be regarded as the @[email protected] concentration of $$i$$ when the @[email protected] is chosen so that $$\mathit{\Gamma}_{i}^{\sigma}$$ is zero, i.e. the @[email protected] is chosen so that the reference system contains the same amount of component 1 as the real system. Hence $$\mathit{\Gamma}_{1}^{\left(1\right)}\equiv 0$$.