Use of combined ion-exclusion and cation-exchange chromatography to study photooxidation of ionic nitrogen compounds on a titanium dioxide photocatalyst

Combined ion-exclusion and cation-exchange chromatography (IEC/CEC) on a weakly acidic cation-exchange resin in the W-form (TSKgel Super IC-A/C) has been used as an advanced method for evaluation of the photooxidation of ionic nitrogen compounds, for example triethanolamine, trimethylamine, and urea, on a TiO2 photocatalyst. Formation of NH4+ and NO3- from each nitrogen compound by photooxidation on the catalyst during UV irradiation was successfully monitored by use of IEC/CEC under optimized mobile-phase conditions (6 mm tartaric acid and 3 mM 18-crown-6). It was found that the products formed depended on whether or not a molecule contained a hydroxylated nitrogen moiety or other hydroxyl group.