Speciation of chromium in environmental samples by dual electromembrane extraction system followed by high performance liquid chromatography

• Speciation of chromium in different water samples.
• Chelating of Cr species with APDC and quantification using HPLC.
• Application of dual electromembrane extraction system.
• Simultaneous extraction of anionic and cationic species of Cr.
• Quantification of Cr(VI) and Cr(III) in tap, mineral and river water samples.

This study proposes the dual electromembrane extraction followed by high performance liquid chromatography for selective separation-preconcentration of Cr(VI) and Cr(III) in different environmental samples. The method was based on the electrokinetic migration of chromium species toward the electrodes with opposite charge into the two different hollow fibers. The extractant was then complexed with ammonium pyrrolidinedithiocarbamate for HPLC analysis. The effects of analytical parameters including pH, type of organic solvent, sample volume, stirring rate, time of extraction and applied voltage were investigated. The results showed that Cr(III) and Cr(VI) could be simultaneously extracted into the two different hollow fibers. Under optimized conditions, the analytes were quantified by HPLC instrument, with acceptable linearity ranging from 20 to 500 μg L−1 (R2 values ≥ 0.9979), and repeatability (RSD) ranging between 9.8% and 13.7% (n = 5). Also, preconcentration factors of 21.8–33 that corresponded to recoveries ranging from 31.1% to 47.2% were achieved for Cr(III) and Cr(VI), respectively. The estimated detection limits (S/N ratio of 3:1) were less than 5.4 μg L−1. Finally, the proposed method was successfully applied to determine Cr(III) and Cr(VI) species in some real water samples.

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