The comparative investigation of several stationary phases containing iminodiacetic functional groups for the high performance chelating exchange chromatography

Three chelating ion-exchangers having iminodiacetic acid functional groups immobilised at the surface of different substrates (silica gel, hydrophilic and hydrophobic polymer matrices) were compared for the separation of various alkaline-earth and transition metal ions. The retention of metal ions on two commercially available Diasorb IDA silica (250 mm x 4 mm id.) and Tosoh TSK Gel Chelate 5 PW (75 x 7 mm id.) columns and column packed with poly(styrene-divinylbenzene) substrate coated with Phthalein Purple dye was investigated in maleate, tartrate and oxalate mobile phases. Metal-ion retention increased with pH and with a decrease in eluent concentration. The complexing ability of ion-exchangers decreased in the order IDA-silica > TSK Gel Chelate 5 PW > polystyrene-divinylbenzene coated with Phthalein Purple dye. The selectivity of separation was similar for IDA-silica and TSK Gel Chelate 5 PW and was slightly different for the dye coated column. The chromatographic separation of metal ions is demonstrated in oxalate and tartrate mobile phases.