Possibilities for speciation of Al-citrate and other negatively charged Al complexes by anion-exchange FPLC-ICP-AES

An anion-exchange fast protein liquid chromatographic-inductively coupled plasma atomic emission spectrometric procedure (FPLC-ICP-AES) was developed for speciation of Al-citrate and other negatively charged Al complexes. FPLC separations were carried out on a Mono Q HR 5/5 strong anion-exchange FPLC column over a pH range from 3.5 to 11.0. An aqueous-NaNO3 (4 mol dm(-3)) linear gradient elution was applied over 10 min for separation of a particular Al species. The separated Al species were determined in 0.5 cm(3) eluate fractions 'off line' by ICP-AES. Under optimal analytical procedures Al-citrate was separated from Al-oxalate and AI-EDTA in a neutral pH range. Good reproducibility of the FPLC-ICP-AES procedure was obtained for determination of a particular Al species al optimal measurement conditions (RSD +/- 2%). Al3+ and neutral Al-citrate species were strongly adsorbed on the column resin and did not interfere with the separation of negatively charged Al complexes. Al(OH)(4)(-) species were separated from Al-citrate in an alkaline pH region, but quantitatively determined only at a pH of 11.0. The distribution of Al species over a pH range from 3.5 to 11.0 agreed with the reported calculated data. The limit of detection (3 sigma basis) for separated Al species was 0.1 mu g cm(-3). (C) 1998 Elsevier Science B.V. All rights reserved.