ELECTROPHORESIS Rapid Capillary Electrophoretic Method for Trace Chromium Speciation Using a Zwitterionic Isoelectric Polymer Coated Capillary and Photodiode Array Detection Marion King, 1 Mirek Macka, 2 and Brett Paull 1, * 1 National Centre for Sensor Research, School of Chemical Sciences, Dublin City University, Dublin, Ireland 2 Australian Centre for Research on Separation Science, School of Chemistry, Faculty of Science, Engineering and Technology, University of Tasmania, Australia ABSTRACT A capillary electrophoretic method has been developed for the rapid screening of water samples for chromium (III) and chromium (VI). Chro- mium (III) and (VI) were separated as the anionic species, chromate and chromium pyridinedicarboxylate (CrL 2 21 ), utilising simple precapillary complexation with 2,6-pyrinedicarboxylic acid (PDCA). The two species were separated using a 30 mM phosphate buffer (pH 6.4) contain- ing 10 mM of N-carboxymethylated polyethyleneimine (CMPEI) to 2771 DOI: 10.1081/AL-200032011 0003-2719 (Print); 1532-236X (Online) Copyright # 2004 by Marcel Dekker, Inc. www.dekker.com *Correspondence: Brett Paull, National Centre for Sensor Research, School of Chemical Sciences, Dublin City University, Dublin 9, Ireland; E-mail: brett.paull@ dcu.ie. ANALYTICAL LETTERS Vol. 37, No. 13, pp. 2771–2787, 2004