Development of simultaneous ion-exclusion/anion-exchange chromatographic determination of ammonium, nitrite and nitrate ions and its application to high-salt content sample

Abstract

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 NO 3- 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 40min at 0.6mL/min of flow rate, by standard addition method. Also, this method was applicable to nitrogen analysis in artificial seawater with iron matrix, by precolumn packed with an iminodiacetate chelating resin in order to remove iron or calcium ions.