METAL ION INTERACTION WITH ANION CHROMATOGRAPHY COLUMNS

Problems associated with metal ion interaction with anion chromatography columns were investigated on four different types of anion exchange columns. Exposure of the columns to metal ions caused significant loss in column capacity in Vydac 302.IC silica and Dionex latex agglomerated polystyrene divinylbenzene columns. For these columns the anion analysis performance was affected as well as a Hamilton PRPX-100 polystyrene divinylbenzene column. A Waters IC PAK polymethacrylate column was only slightly affected. Metal ions, when present in the sample, interfered with chloride analysis using any of the 4 column types. The mechanism of metal retention was determined indirectly and the results indicated that for all columns except the Dionex column the metal ions formed complexes with phthalate in the eluent and the complexes were retained in the column by a reverse phase mechanism. For the Dionex column, it was concluded that the metal ions were retained by an ion exchange process.