Purification of EDTA Monitored by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES)

Abstract

The viability and limitations of inductively coupled plasma atomic emission spectrometry (ICP-AES) for trace characterization of concentrated EDTA solutions are determined Qualitative detection of elemental impurities based on multielement scans, semiquantitative estimates of impurity levels obtained by comparison of results with calibration graphs in the 1 to 5 µg/mL range, and quantitative analyses via standard addition methods involving EDTA solutions doped with trace metals in the 01 to 10 µg/mL, and in the 001 to 016 µg/mL ranges are reported Applications of the method to the analysis of EDTA, purified by recrystallization, and to the monitoring of EDTA solutions, electrolyzed at the mercury cathode, are described Mercury cathode electrolysis is superior to the recrystallization method only in the case of removal of Cd, Cu, and Fe The recrystallization procedure provides the greater advantage of reducing the levels of a broader range of trace elements than was possible by electrolysis Both methods reduce amenable trace elemental impurities in EDTA solutions to the 100 ng/mL level or below