DETERMINATION OF METAL-IONS AS EDTA COMPLEXES BY REVERSED-PHASE ION-PAIR LIQUID-CHROMATOGRAPHY

A reversed-phase ion-pair liquid chromatographic method was developed for the determination of metal ions in aqueous solution. Metal ions were first chelated with EDTA, followed by injection into the chromatographic system. A reversed-phase C-8 column was used to separate the chelate ions with an eluent consisting of acetonitrile-water mixture (8 + 92, v/v) containing 0.002 M tetrabutylammonium as the counter ion. UV detection at 242 nm was applied. Factors affecting the ion-pair formation and the chromatographic separation were studied. This method can be applied to the determination of metal ions such as Pb, Ni, Cd, Fe and Cu. The linear dynamic range is larger than two orders of magnitude, the detection limit is at the ng ml-1 level and the R.S.D. is ca. 3% at mid-calibration range. The method has been successfully used in metal analysis of electroplating waste water. The results are comparable to those of atomic absorption spectrometry.