Chromium speciation using an aminated amberlite XAD-4 resin column combined with microsample injection-flame atomic absorption spectrometry

Abstract

Amberlite XAD-4 resin (AXAD-4) was chemically modified to an aminated Amberlite XAD-4 (AAXAD-4) resin and characterized by infrared spectroscopy. AAXAD-4 resin was used as an efficient solid phase for the preconcentration and speciation of Cr(III) and Cr(VI) ions by column technique. The concentration of chromium species was determined by microsample injection system-flame atomic absorption spectrometer (MIS-FAAS). Selective retention of Cr(III) ions was achieved at pH 8.0 and eluted using 1.0 mL of 3.0 mol L–1 HCl and 1.0 mL of 2.0 mol L–1 NaOH, successively, at the flow rate of 5.0 mL min–1. The maximal sorption capacity of AAXAD-4 resin for Cr(III) ions was found to be 67.0 mg g–1. The limit of detection (LOD) and limit of quantitation (LOQ) for Cr(III) ions were found to be 0.041 and 0.131 µg L–1, respectively, with preconcentration factor (PF) of 375 and relative standard deviation (RSD) of 3.75% (n = 11). The method was validated using certified reference materials (CRMs) and successfully applied to the real samples, spiked with Cr(III) and Cr(VI) ions.