Determination of Dissolved and Adsorbed EDTA Species in Water and Sediments by HPLC

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Abstract
This paper describes a method for determining EDTA species in various environmental samples at low molar concentrations by high-performance liquid chromatography (HPLC). Distinction between FeIIIEDTA and all the other species can be made. NiEDTA can be detected semiquantitatively. The fraction of EDTA adsorbed to suspended particles or to sediments can be determined after desorption with phosphate. After complexation with Fe(III), the EDTA is detected by reversed-phase ion-pair liquid chromatography as the FeIIIEDTA complex at a wavelength of 258 nm. The behavior of a variety of metal−EDTA complexes during analysis was checked. Determination of different EDTA species (FeIIIEDTA, NiEDTA, and adsorbed EDTA) is possible in river water, groundwater, and effluents from wastewater treatment plants. FeIIIEDTA was found to be the main species, at 30−70%; NiEDTA was <10% in most of the samples. Adsorbed EDTA was detected in suspended particles from rivers and wastewater treatment plants and in sediment cores from a lake. The method is suitable for a variety of different samples with different concentration ranges.