Simultaneous chromatographic separation of nitrate ion (NO3−), nitrite ion (NO2−) and ammonium ion (NH4+) was obtained using single injection, single column and a detector (conductivity). The principle is based on selective ion-exclusion effect for NH4+ and anion-exchange effects for NO3− and NO2− on an OH−-formed basic anion-exchange resin column (Tosoh TSKgel Super IC-AZ) with basic eluent (2 mol/m3 KOH). The present system could determine NH4+, NO2− and NO3− in 500-fold diluted artificial seawater sample in 40 min at 0.6 mL/min of flow rate, by standard addition method. Also, this method was applicable to nitrogen analysis in artificial seawater with iron matrix, by pre-column packed with an iminodiacetate chelating resin in order to remove iron or calcium ions.
