Original Paper

Microchimica Acta

, Volume 166, Issue 1, pp 69-75

First online:

Speciation of chromium in water samples using dispersive liquid–liquid microextraction and flame atomic absorption spectrometry

  • Payam HemmatkhahAffiliated withDepartment of Analytical Chemistry, Faculty of Chemistry, Iran University of Science and TechnologyElectroanalytical Chemistry Research Center, Iran University of Science and Technology
  • , Araz BidariAffiliated withDepartment of Analytical Chemistry, Faculty of Chemistry, Iran University of Science and TechnologyElectroanalytical Chemistry Research Center, Iran University of Science and Technology
  • , Sanaz JafarvandAffiliated withDepartment of Analytical Chemistry, Faculty of Chemistry, Iran University of Science and TechnologyElectroanalytical Chemistry Research Center, Iran University of Science and Technology
  • , Mohammad Reza Milani HosseiniAffiliated withDepartment of Analytical Chemistry, Faculty of Chemistry, Iran University of Science and TechnologyElectroanalytical Chemistry Research Center, Iran University of Science and Technology
  • , Yaghoub AssadiAffiliated withDepartment of Analytical Chemistry, Faculty of Chemistry, Iran University of Science and TechnologyElectroanalytical Chemistry Research Center, Iran University of Science and Technology Email author 

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Abstract

A novel method for preconcentration is described for chromium speciation at microgram per liter to sub-microgram per liter levels. It is based on selective complex formation of both Cr(VI) and Cr(III) followed by dispersive liquid–liquid microextraction and determination by microsample introduction-flame atomic absorption spectrometry. Effects influencing complex formation and extraction (such as pH, temperature, time, solvent, salinity and the amount of chelating agent) have been optimized. Enrichment factors up to 275 and 262 were obtained for Cr(VI) and total Cr, respectively. The calibration graph is linear from 0.3 to 20 µg L−1, and detection limits are 0.07 and 0.08 µg L−1 for Cr(VI) and total Cr, respectively. Relative standard deviations (RSDs) were obtained to be 2.0% for Cr(VI) and 2.6% for total Cr (n = 7).

Keywords

Dispersive liquid–liquid microextraction Chromium speciation Preconcentration Flame atomic absorption spectrometry Microsample introduction Water analysis