Use of ion chromatography for the determination of transition metals in the control of sewage-treatment-plant and related waters

Transition metals [Fe(III), Fe(II), Cu, Ni, Zn, Co, Cd, Mn] were separated using a mixed-bed ion-exchange column (Dionex IonPac CS5A). A pyridine2-6-dicarboxylic acid eluent was used and detection was accomplished using post-column reaction with 4-(2-pyridylazo)resorcinol and absorbance monitoring at 530 nm. Under the suggested chromatographic conditions both Mg2+ and Ca2+, up to 0.1 g/l and 0.3 g/l, respectively, do not interfere with separation quantitation. Detection limits ranged from 0.06 mu g/l for Co(II) to 0.38 mu g/l for Fe(II). The calibration graphs were linear (r(2)>0.986) over two orders of magnitude (5-5000 mu g/(l)). The selective separation of eight metals in 20 min was obtained and the method was applied to the analysis of natural and waste waters related to the maintenance of a sewage treatment plant.