DETERMINATION OF LEAD IN WATER SAMPLES USING ION CHROMATOGRAPHY WITH A XYLENOL ORANGE CONTAINING ELUENT

A simple ion chromatographic method has been developed for the determination of Pb(II) in polluted water samples, based upon the use of a colour-forming eluent and visible detection. Using the combination of a strong cation exchange column (HiChrom P10SCX) and an eluent consisting of 20mM sodium acetate-acetic acid buffer (~pH = 4.2) and 0.2mM xylenol orange, Pb(II) eluted as a reasonably sharp peak between 5 and 6.5 min (depending upon exact pH). Retention was due to a combination of cation exchange and surface adsorption, with sufficient eluent complexation with xylenol orange to allow sensitive visible detection at 572 nm, thus removing the need for complicated post-column reaction systems. The method showed a linear response over the range 0.05 to 20 mg/L Pb(II) with a detection limit (100 µL inj.) of 30 ± 5 µg/L. The method was highly selective, with only Fe(III) causing a eluent dip. The method was successfully applied to the analysis of a spiked river water sample and a polluted drainage sample.