The use of two ion chromatographic systems, with and without a chemical conductivity suppressor, is described for the determination of Cl - , NO - 3 , PO 3 - 4 and SO 2 - 4 in plant sap. Samples were prepared just by dilution. Separations have suffered from interference due to the presence of other solutes. Usually, organic acid ions such as malate coelute with sulphate ions on the non-suppressed system. An appropriate eluent, formed with boric and tartaric acids at pH 4.0, was used to overcome this problem. Organic acids were eliminated in the void volume but phosphate appeared as a negative peak and cannot be quantitated. Suppressed ion chromatography permits the measurement to be performed with more efficiency, but coelutions also occurred with carbonate-hydrogencarbonate eluent for Cl - and SO 2 - 4 . The best separation of ions was achieved on the Dionex AS 11 column with a sodium hydroxide gradient elution and a 5 min running time. The selectivity and sensitivity of the methods are discussed.