title: Selective and sensitive speciation analysis of Cr(VI) and Cr(III), at sub-μgL-1levels in water samples by electrothermal atomic absorption spectrometry after electromembrane extraction.
abstract: In this work, electromembrane extraction in combination with electrothermal atomic absorption spectrometry (ET-AAS) was investigated for speciation, preconcentration and quantification of Cr(VI) and Cr(III) in water samples through the selective complexation of Cr(VI) with 1,5-diphenylcarbazide (DPC) as a complexing agent. DPC reduces Cr(VI) to Cr(III) ions and then Cr(III) species are extracted based on electrokinetic migration of their cationic complex (Cr(III)-DPC) toward the negative electrode placed in the hollow fiber. Also, once oxidized to Cr(VI), Cr(III) ions in initial sample were determined by this procedure. The influence of extraction parameters such as pH, type of organic solvent, chelating agent concentration, stirring rate, extraction time and applied voltage were evaluated following a one-at-a-time optimization approach. Under optimized conditions, the extracted analyte was quantified by ETAAS, with an acceptable linearity in the range of 0.05-5ngmL-1(R2value=0.996), and a repeatability (%RSD) between 3.7% and 12.2% (n=4) for 5.0 and 1.0ngmL-1of Cr(VI), respectively. Also, we obtained an enrichment factor of 110 that corresponded to the recovery of 66%. The detection limit (S/N ratio of 3:1) was 0.02ngmL-1. Finally, this new method was successfully employed to determine Cr(III) and Cr(VI) species in real water samples.
authors: Faculty of Chemistry, Shahid Beheshti University, G.C., 1983963113 Evin, Tehran, Iran.
authors: Zeinab
authors: Z
authors: Tahmasebi
authors: Faculty of Chemistry, Shahid Beheshti University, G.C., 1983963113 Evin, Tehran, Iran. Electronic address: ss-hosseiny@sbu.ac.ir.
authors: Saied Saeed Hosseiny
authors: SSH
authors: Davarani
keywords: 1,5-Diphenylcarbazide; Electromembrane extraction; Electrothermal atomic absorption spectrometry; Selective extraction; Speciation analysis; Water samples