Study on the Large Volume Stacking Using the EOF Pump (LVSEP) for Analysis of EDTA by Capillary Electrophoresis

Abstract

The widespread use of ethylenediaminetetraacetic acid (EDTA) has requested an urgent monitoring program regarding surface and drinking water. Analyzing EDTA at low-level concentrations such as µg l -1 in the environmental samples is quite complex using conventional methods. In this study, a simple, quick and sensitive capillary electrophoretic technique -large volume stacking using the EOF pump (LVSEP) -has been developed for determining EDTA in drinking water for the first time (EOF: electroosmotic flow). It is based on a precapillary complexation of EDTA with Fe(III) ions, followed by LVSEP and direct UV detection at 258 nm. The curve of peak response vs. concentration was linear between 5.0 and 600.0 µg l -1 , as well as between 0.7 and 30.0 mg l -1 . The regression coefficients were 0.9988 and 0.9990, respectively. The detection limit of current technique for EDTA analysis was 0.2 µg l -1 with additional 10-fold preconcentration procedure, based on the signal-tonoise ratio of 3. As opposed to the classical capillary electrophoresis (CE) method, a 1 000-fold concentration factor could be smoothly achieved on this LVSEP method. To the best of our knowledge, it represents the highest sensitivity for EDTA analysis via CE. Several drinking water samples were tested by this novel method with satisfactory results.