Chlorocomplex:

In the case of iron (III) chlorocomplex, the slope will be one and for Zinc (II) and Cd(II) chlorocomplexes, that will be two. Ideally, to drawing the plot, it should be the concentration of the free (unbound) amine. This should be the amine concentration at equilibrium. Since the amine concentration taken is about 103times more than the metal ion concentration, the free amine concentration is taken to be the same as the initial one. In this regard, the use of radiotracers for the determination of D is very useful because the metal ion concentration required is almost negligible ~ 10 ^-6 M.

That means the free amine concentration could be safely taken as the initial one.

There are other methods, including the spectroscopic, which are used for confirming the postulated extracting species or the proposed extraction equilibrium.

From the above examples of extraction in high molecular weight amines, similar to anion exchange, some authors draw analogy to classify alkylphosphoric acids, carboxylic acids and sulphonic acids as liquid cation exchangers. These acids, in the organic phase, commonly exist as dimers. The equilibrium step resulting into the transfer of the metal ion in the organic phase will be somewhat to a cation exchange.

M ^{n +}_a + n (HX)_2o ↔   M(HX)_{n o} +  n H⁺_a

It may be important to point out here that the analogy of high molecular weight amines and that of the acids to anion and cation exchangers should not be extended too far. Here, we have taken some simple equilibria. However, the parameters which can complicate the situation are role of diluent, dimerization of the extractant and the extractant simultaneously acting as an exchanger and a solvating agent. One needs to be cautious in this regard.