LIQUID-CHROMATOGRAPHIC DETERMINATION OF ETHYLENEDIAMINETETRAACETIC ACID AS METAL-COMPLEXES ON A POROUS GRAPHITIC CARBON COLUMN

A novel liquid chromatographic system for determination of ethylenedia minetetraacetic acid (EDTA), using a complex-forming metal ion [Fe(III )] in the eluent was developed. Optimisation of the system was obtaine d after a careful choice of complex-forming metal and pH of the eluent . The porous graphitic carbon column permits use of a wide pH range an d due to its high hydrophobicity it is possible to determine EDTA with out addition of ion-pair reagents to the eluent. The chromatographic b ehaviour of the Fe(III) complex, the free EDTA and Fe(III) ions were c onsidered and possible pitfalls due to equilibrium disturbances are sh own and discussed. Applications to analysis of EDTA in local anaesthet ic parental solutions and determination of nitrilotriacetic acid as an impurity in EDTA substance are given.