Maria Concetta Bruzzoniti,a Peter Hajos,b Krisztian Horvath,b Corrado Sarzaninia*
aUniversity
of Torino, Department of Analytical Chemistry, Via P. Giuria 5, I-10125 Torino,
Italy.
Tel.: +39(011)6707628,
Fax:
+39(011)6707615,
E-mail: corrado.sarzanini@unito.it.
bUniversity
of Pannonia, Department of Analytical Chemistry, Egyetem Utca 10, POB 158,
Veszprem, Hungary
Paper based on a presentation at the 12th
International Symposium on Separation Sciences, Lipica, Slovenia,
September
27–29, 2006.
Abstract
Retention behaviour of inorganic anions was
investigated on a cryptand-based anion exchange column (Cryptand A1) using NaOH
and KOH-based eluents. Due to the ability of the macrocycle to bind cations, the
positively charged metalcryptand complexes act as anion exchange sites. In
addition, cryptand can be partially protonated and in this form also behaves as
anion exchanger. Considering the complexation and protonation mechanisms a
theoretical retention model and a general equation were developed for describing
the simultaneous effect of the nature and concentration of the eluent on the
retention factor k. The parameters of the model were iterated and the ion
exchange constants were computed, theoretical and experimental data show a good
correspondence with correlation coefficients (r2)
0.9987-0.9998 for KOH and 0.9717-0.9883 for NaOH, experimental and computed data
differ maximally 5%.
Keywords: ion chromatography, retention mechanism, macrocyclic ligand.