N. Cardellicchio et al., New strategies for determination of transition metals by complexation ion-exchange chromatography and post column reaction, J CHROMAT A, 847(1-2), 1999, pp. 251-259
A method for the simultaneous determination of metals (Fe3+, Fe2+, Cu, Ni,
Zn, Co, Cd, Mn and Pb) at mu g/l levels in environmental matrices is demons
trated. The metals are separated by ion chromatography on a mixed-bead ion-
exchange column (IonPac CSSA) and detected by post-column reaction and spec
trophotometric detection. The use of a gradient program (based on oxalic ac
id-hydrochloric acid-sodium chloride and sodium nitrate eluents) allows the
separation of nine metals in a single run. The direct injection of a large
volume of samples lowers the detection limits to below and/or few mu g/l.
The chromatographic conditions and colour-development reaction were optimis
ed. Two post-column reagents, 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol
(5-Br-PADAP) and 4-(2-pyridylazo) resorcinol, were tested and detection li
mits were compared. The use of 5-Br-PADAP increased the sensibility for Cu,
Cd, Zn and Mn. For the proposed method, linearity, reproducibility, detect
ion limits and interference due to alkaline-earth metals (noticeably Mg and
Ca) were discussed. Under the suggested chromatographic conditions Mg2+ an
d Ca2+ up to 0.2 g/l do not interfere with separation and quantitative anal
ysis of the metals. The calibration graphs were linear (r(2)>0.986) in the
range 5-5000 mu g/l. The application of the method to the determination of
metals in coastal marine sediments is shown. (C) 1999 Published by Elsevier
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