Fig. 5. Comparison of HETP values as function of specific resin
x1 y1 Me is eluted by a competing cation, E and the capacity for sulfonated BioGel SEC 7 PS–DVB resins for
eluent also contains a complexing reagent capable of comparable retention factors k9.
x1 reacting with Me , the whole retention model has to
consider this complex formation process [14]. The nated resins with increased degree of complexation
21 21 fraction of the total concentration of metal ion in the of the cations. The HETP for Zn and Ni with
eluent which is present in free form can be expressed stability constants of 479, respectively, 398 decrease
as: about 30% by increasing the fraction of non-complexed
metal ion from 7.7 to 30%, respectively, 9.1
[MeL] Me21L22MeL with K 5]]]] (2) to 33.7%. The HETP for Mg with a one order of L 21 22 [Me ][L ] magnitude lower stability constant remains nearly
x1 unchanged [15,16].