Reverse polarity capillary zone electrophoretic determination of ethylenediaminetetraacetic acid andN-hydroxyethyl ethylenediaminetriacetic acid in Hanford defense waste

Abstract

Previous attempts analyzing EDTA, HEDTA in Hanford defense waste (HDW) under acidic conditions involved laborious, time consuming, expensive sample pretreatment. Unsatisfactory results of poor percentages of recoveries and interferences were obtained in analyses. This investigation describes reverse polarity capillary zone electrophoretic (RPCE) analysis of HDW samples for EDTA, HEDTA under basic conditions. RPCE separation was carried out in borate buffer containing hexamethonium bromide, electroosmotic flow modifier at 9.2 pH. Synthetic Hanford waste analysis for EDTA, HEDTA by standard addition calibration method showed addition of citrate as releasing agent resulted in 95% recovery for EDTA and 85% recovery for HEDTA. Addition of excess lead(II)/citrate solution under basic conditions resulted in better than 95% recoveries for EDTA and HEDTA. RPCE method was used for analysis of real HDW samples by adding excess lead(II)/citrate solution under basic conditions obtaining total EDTA, HEDTA as Pb(II) complexes. Detection limits obtained in aqueous basic solution were 10 and 9.8 μM for uncomplexed EDTA, HEDTA, respectively, and 3.8 and 4.8 μM for PbEDTA2−, PbHEDTA−, respectively. In HDW, detection limits were 7.8 and 11.5 μM for PbEDTA2−, PbHEDTA−, respectively. Method reliability test based on matrix spike recoveries in HDW were 90–116% for EDTA and 74–108% for HEDTA. RPCE method was anion specific, reduced overall time of analysis, free of interferences, required small sample volumes which served to decrease mixed radioactive waste and radiation exposure. Results of analyses were a significant contribution to Organic Tank Safety Project at US-DOE Hanford Site, Richland, Washington. ©2000 John Wiley & Sons, Inc. J Micro Sep 12: 48–56, 2000