Muhammed Aslam Mirza Muhammad Yar Khuhawar Rafee Arain Dr. M. A. Kazi Institute of Chemistry, University of Sindh, Jamshoro, Pakistan Received June 8, 2007 Revised August 7, 2007 Accepted August 8, 2007 Research Article Determination of uranium, iron, copper, and nickel from ore samples by MEKC using N,N 0 -ethylene bis(salicylaldimine) as complexing reagent An analytical procedure has been developed for the separation of dioxouranium(VI), iron(III), copper(II), nickel(II), cobalt(II), cobalt(III), palladium(II), and thorium(IV) by MEKC using N,N 0 -ethylene bis(salicylaldimine) (H 2 SA 2 en) as a complexing reagent with total runtime ,4.5 min. SDS was used as micellar medium at pH 8 with sodium tetra- borate buffer (0.1 M). An uncoated fused-silica capillary with an effective length of 50 cm675 mm id was used with an applied voltage of 30 kV with photodiode array detec- tion at 231 nm. Linear calibrations were obtained within 0.111–1000 mg/mL of each ele- ment with LODs within 37–325 ng/mL. The developed method was tested for analysis of uranium ore samples indicating its presence within 103–1789 mg/g with RSD within 0.79– 1.87%. Likewise copper, nickel, and iron in their combined matrix were also simultaneously determined with RSD 0.4–1.6% (n = 6). Keywords: MEKC / N,N 0 -Ethylene bis(salicylaldimine) / Ores / Sodium dodecyl sulfate / Ura- nium DOI 10.1002/elps.200700414 Electrophoresis 2008, 29, 597–603 597 1 Introduction The sensitive and selective determination of uranium with short analysis time and broad calibration range continues to be of analytical interest. The analytical procedures for the determination of uranium comprises mainly of inductively coupled plasma-MS (ICP-MS) [1–5], inductively coupled plasma-atomic emission spectrometry (ICP-AES) [6], total reflection X-ray fluorescence spectrometry [7], activation analysis [8], cathodic striping voltammetry [9], kinetic phos- phorescence [10], fluorimetery [11], spectrophotometry [12, 13], and HPLC [14–17]. HPLC methods combined with pre- column derivatization are interesting, especially when an appropriate complexing reagent is used. CE as an analytical technique has grown steadily in popularity and its main advantages include reduced method development time, reduced operating cost, low solvent con- sumption, high separation efficiencies, and analysis of solutes with limited UV chromophores [18]. In the past, simple buffer solutions were employed to separate ionic water-soluble solutes. However, as CE developed, the range of solute types has also greatly expanded. The sparingly water-soluble samples have been addressed by the use of NACE, micellar EKC (MEKC), and microemulsion EKC (MEEKC). In MEKC, surfactants are added to the buffer so- lution to make up CMC. The separation principle of MEKC is based on differential partition between the buffered aque- ous mobile phase and micellar (pseudo) stationary phase and is the basis for the separation of neutral molecules [19]. N,N 0 -Ethylene bis(salicylaldimine), [bis(salicylaldehyde)] ethylenediimene H 2 SA 2 en (Fig. 1) has been exclusively studied as the complexing reagent for copper(II), nickel(II), palla- dium(II), platinum(II), iron(II), iron(III), cobalt(II), cobalt(III), manganese(II), oxovanadium(IV), oxochromium(V), dioxomo- lybdenum(VI), and dioxouranium(VI) [20–37]. The uranyl complex of H 2 SA 2 en was reported as early as 1937 [35]. Pasini et al. [24] and El-Sonbati [37] have reported the nature of uranyl complex with tetradentate shiff bases including H 2 SA 2 en. Uden et al. [38, 39] used H 2 SA 2 en for the HPLC separation and deter- mination of copper(II), nickel(II), and palladium(II) using nor- mal and RP modes with LODs in the low nanogram/injection range. The reagent can easily be prepared from simple and inexpensive laboratory chemicals in good yield (90% theoreti- cal). It reacts with a limited number of metal ions at all con- Correspondence: Dr. Muhammed Y. Khuhawar, Dr. M. A. Kazi Institute of Chemistry, University of Sindh, Jamshoro, Pakistan E-mail: kanwalseemi@yahoo.com, makashmiri2006@yahoo.com Fax: 192-222-771372 Abbreviation: H 2 SA 2 en, N,N 0 -ethylene bis(salicylaldimine)  2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.electrophoresis-journal.com