title: Speciation of chromium in environmental samples by dual electromembrane extraction system followed by high performance liquid chromatography.
abstract: 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) (R(2) 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.
authors.affiliation: Faculty of Chemistry, Shahid Beheshti University, Tehran, Iran.
authors.forename: Meysam
authors.initials: M
authors.lastname: Safari
authors.forename: Saeed
authors.initials: S
authors.lastname: Nojavan
authors.forename: Saied Saeed Hosseiny
authors.initials: SS
authors.lastname: Davarani
authors.forename: Amin
authors.initials: A
authors.lastname: Morteza-Najarian
mesh_terms: D000838:Anions / Q000302:isolation & purification; D002412:Cations / Q000302:isolation & purification; D005591:Chemical Fractionation / Q000295:instrumentation / Q000379:methods*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002857:Chromium / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D055664:Electrochemical Techniques; D004566:Electrodes; D004867:Equipment Design; D006863:Hydrogen-Ion Concentration; D057230:Limit of Detection; D059627:Liquid Phase Microextraction / Q000379:methods; D011759:Pyrrolidines / Q000737:chemistry; D015203:Reproducibility of Results; D045483:Rivers / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013859:Thiocarbamates / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D000838:Anions; D002412:Cations; D011759:Pyrrolidines; D012997:Solvents; D013859:Thiocarbamates; D014874:Water Pollutants, Chemical; D002857:Chromium; C020972:pyrrolidine dithiocarbamic acid
keywords: 2-nitrophenyl octyl ether; APDC; CPE; Chromium speciation; DEME; Dual electromembrane extraction; Environmental samples; FAAS; HF; ICP; Liquid phase microextraction; NPOE; ammonium pyrrolidinedithiocarbamate; cloud point extraction; dual electromembrane extraction; flame atomic absorption spectroscopy; hollow fiber; inductively coupled plasma