Sample Conservation Prior to Total EDTA and Fe(III)EDTA Measurements

Abstract

Ethylenediamine tetraacetic acid (EDTA) is a potent chelating agent and has the potential to affect the environmental mobility of heavy metals. A reliable quantification of EDTA and its speciation is required in order to accurately estimate the actual impact of this compound on the aquatic environment. This study aimed to determine the optimal conservation conditions for samples in order to accurately measure EDTA speciation and total EDTA concentration. The results obtained by studying the effects of time elapsed between sampling, conditioning [i.e., addition of reagents to complex EDTA with Fe (III)], and analysis show that the determination of EDTA speciation needs to be carried out immediately after sampling. The measurement of total EDTA may be performed within 2 mo, as long as the sample is filtered and conditioned on the day of sampling.

We are grateful to the staff of the wastewater treatment plant Aïre for their help in sample collection and to the government of the Canton of Geneva, which funded this research. We also thank Dr Madeleine Biber for helping us with the English.