Determination of EDTA in Dairy Wastewater and Adjacent Surface Water

An HPLC-UV analytical method was developed to determine ethylenediaminetetraacetic acid (EDTA) in dairy wastewater and surface water. The optimizing separation was achieved by reversed–phase ion-pair liquid chromatography on a C18 column using methanol as mobile phase solvent, tetrabutylammonium bromide as the ion-pair reagent in pH 3.3 formate buffer solution at a flow rate of 0.9 mL min with a UV detector at 265 nm. No interference of Ca, Mg or NO3 was detected. Method performance was evaluated in terms of linearity, repeatability and reproducibility. The method detection limit was 5 μg L. The contents of EDTA in dairy effluents were 72 ~ 261 μg L at a large dairy site. A change of EDTA concentration was observed downstream of the dairy effluent discharge, but this was well under the predicted no effect concentration for aquatic ecosystem. Keywords—Dairy wastewater, EDTA, HPLC, surface water.