Ion chromatography of heavy and transition metals by on- and post-column derivatizations

A new method for the simultaneous separation and determination of mercury(II) with other heavy and transition metals by ion chromatography (IC) was developed. This method involves on-column derivatization with 2,6-pyridinedicarboxylic acid (PDCA) and anion-exchange separation, followed by a post-column reaction with 2-[(5-bromo-2-pyridyl)-azo]-5-diethylaminophenol (5-Br-PADAP) to form metal-5-Br-PADAP chelates, which can be sensitively monitored by spectrophotometric detection at 565 nm. PDCA was first combined with Na2C2O4 to separate the metals within 16 min. The optimum separation and derivatization conditions were studied in detail. The detection limits of Pb2+, CU2+, Ni2+ Zn2+, Co2+, Cd2+, Mn2+ and Hg2+ were 0.2 mgl(-1) (115 mu l loop), 1.5, 5, 0.5, 5, 5, 3 and 20 mu gl(-1) (676 mu l loop), respectively. This method was applied to the analysis of standard rice sample, waste cellpacking and municipal solid waste fly ash with satisfying results. (C) 2000 Elsevier Science B.V. All rights reserved.