Investigation of the ion-exchange behaviour of titania: Application as a packing material for ion chromatography

Abstract

Titania synthesized in this laboratory has previously been tested under reversed-phase conditions to assess its ion-exchange behaviour. Although in reversed-phase chromatography with acetic acid-sodium acetate buffer as mobile phase titania behaved as an anion-exchanger only, retention data suggested either that it behaved as a cation exchanger at higher mobile phase pH or that the retention of cationic solutes was inhibited under these conditions. The objective of our research was to clarify this point and to use titania as a packing material for ion-exchange separation. Glycine-NaCl-NaOH and glycine-NaOH buffers were used to investigate the retention behaviour of cationic solutes. When glycine-NaCl-NaOH buffer was used to increase mobile phase pH a cationic solute was not retained. In the absence of NaCl in the buffer the solute was strongly retained and its retention decreased with an increasing pH, implying that the retention of the solute was inhibited under these conditions. When dilute acetic acid-sodium acetate or bicine-NaOH buffers were used as mobile phase the titania acted as a anion- and cation-exchanger; it retained fluoride ion strongly under the range of conditions in which it acted as a cation-exchanger. We concluded that the titania had anion- and cation-exchange properties and that the material could possibly be used for simultaneous analysis of anions and cations and as a selective packing material for ion chromatography.