Analysis of Cobalt(II)EDTA and Cobalt(III)EDTA in Pore Water by Ion Chromatography

Abstract Monitoring and restoration activities at contaminated waste facilities throughout the USA have identified complicated mixtures of organic and inorganic contaminants in soil and groundwater. Inorganic contaminants are sometimes associated with various chelating agents (termed co‐contaminants ), which alter the geochemical behavior of the contaminants in subsurface environments. Until recently, the significance of the chelating agents was usually dismissed, and they were not routinely measured as part of environmental compliance programs. A method is presented for separating and quantifying the common subsurface co‐contaminant species of CoEDTA in aqueous solution. Cobalt(II)EDTA and Co(III)EDTA are separated by an ion chromatograph using a carbonate, bicarbonate eluant, and quantified in the presence of common pore‐water inorganic anions using electrical conductivity and visible light detectors. The chromatograph detects Co(II)‐EDTA to 0.6 µmol L −1 with a linear range >4000 µmol L −1 . Cobalt‐(III)EDTA is detected to 1.8 µmol L −1 with a linear range >860 µmol L −1 . The method has application in basic scientific research and environmental restoration activities.