Trace analysis of heavy metals in groundwater samples by ion chromatography with post-column reaction and ultraviolet-visible detection

Groundwaters originating from local and regional aquifers surrounding ash d eposits produced by a coal-fired power plant were collected. These water sa mples were chemically analyzed for quantifying their heavy metal compositio n at trace levels. A highly sensitive analytical technique based on ion chr omatography with a UV-Vis detector and under isocratic eluent flow-rate con ditions was used. In order to quantify the major heavy metals (Pb, Cu, Cd, Co, Zn and Ni), three ionic separation column systems were evaluated: (1) a cationic column (HPIC-CS2, Dionex) tested with two eluents (10 mM oxalic a cid-7.5 mM citric acid; and 40 mM D-tartaric acid-12 mM citric acid); (2) a n anionic column (HPIC-AS4, Dionex) evaluated with 25 mM oxalic acid as elu ent; and (3) a bifunctional ion-exchange column (Ionpac CS5, Dionex) which was also tested with two eluents (6 mM pyridine, 2,6-dicarboxylic acid; and 50 mM oxalic acid/95 mM lithium hydroxide). The lowest detection limits ac hieved with the lonpac CS5 column and the 50 mM oxalic acid-95 mM lithium h ydroxide eluent enabled the heavy metal analysis in groundwater samples to be reliably performed. Details of this comparative study, including the ion chromatography procedure selected and its application to heavy metal analy sis of groundwater samples, are presented in tills work. (C) 2000 Elsevier Science B.V. All rights reserved.