ION-CHROMATOGRAPHIC BEHAVIOR OF ALKALI AND ALKALINE-EARTH METAL-CATIONS ON SILICA-GEL COLUMNS WITH CATION-EXCHANGE CHARACTERISTICS

Ion chromatographic behavior of alkali metal cations and ammonium ion on various unmodified silica gel columns by elution with 2 mM nitric a cid (pH 2.7) was investigated. As a result it was found that one silic a gel (Develosil 30-5) column acted as a cation exchange column under acidic eluent conditions and an excellent separation of these cations was achieved. Therefore, in order to produce silica gel, which acts as a cation exchanger for ion chromatography under strongly acidic condi tions, the main cause of the cation exchange characteristics of the De velosil 30-5 silica gel was investigated. As a result it was found tha t the main cause could be attributed to aluminium present as an impuri ty in the silica gel. This finding Suggests that the modification of s ilica gel with aluminium is very useful for the production of new adva nced silica-based cation exchangers for ion chromatography. (C) 1998 E lsevier Science B.V.