4. Conclusions
The better HETP values for the sulfoacylated
resins are a good indication of possible clogging or It has been shown that column performance for the
filling of smaller pores due to the bonding process of separation of cations by ion chromatography is
a sterically hindered reagent-catalyst complex re- controlled by a variety of factors. The main conclusulting
in higher diffusion coefficients and obstruc- sions of this work may be summarized as follows:
tion factors in the stationary phase as well as lower (1) This, and our previous three publications
fraction of the mobile phase and shorter diffusion [6,7,19], show two selected cases where one or a
distance inside the porous bed, which are in good series of surface reactions can lead to the introconformity
with the percolation theory [18]. duction of permanently bonded sulfonic acid groups
onto PS–DVB resins in order to produce strong
3.4. Comparison of chromatographic performance cation-exchangers which are stable over a wide range
with commercial silica based ion-exchangers of solvent composition and pH. Other modifications,
i.e. surface coating, are also possible. Nevertheless,
The theoretical plate counts for the three polymer the chromatographic performance of the functionbased
cation-exchangers and for the BioSil CAT alized materials are dramatically depending on the
exchange column (capacity: 0.55 mmol/ml) as an functional group structure. The plate height obtained