Application of a surfactant-assisted dispersive liquid-liquid microextraction method along with central composite design for micro-volume based spectrophotometric determination of low level of Cr(VI) ions in aquatic samples

Hamid Reza Sobhi; Efat Azadikhah; Mohammad Behbahani; Ali Esrafili; Mahnaz Ghambarian

doi:10.1016/j.saa.2018.05.031

Application of a surfactant-assisted dispersive liquid-liquid microextraction method along with central composite design for micro-volume based spectrophotometric determination of low level of Cr(VI) ions in aquatic samples

Spectrochim Acta A Mol Biomol Spectrosc. 2018 Sep 5:202:36-40. doi: 10.1016/j.saa.2018.05.031. Epub 2018 May 9.

Authors

Hamid Reza Sobhi¹, Efat Azadikhah², Mohammad Behbahani³, Ali Esrafili⁴, Mahnaz Ghambarian⁵

Affiliations

¹ Department of Chemistry, Payame Noor University, Tehran, Iran. Electronic address: h.sobhi@pnu.ac.ir.
² Department of Chemistry, Payame Noor University, Tehran, Iran.
³ Faculty of Engineering, Shohadaye Hoveizeh University of Technology, Dasht-e Azadegan, Susangerd, Iran.
⁴ Research Center for Environmental Health Technology, Iran University of Medical Sciences, Iran; Department of Environmental Health Engineering, School of Public Health, Iran University of Medical Sciences, Tehran, Iran.
⁵ Iranian Research and Development Center for Chemical Industries, ACECR, Tehran, Iran.

PMID: 29777932
DOI: 10.1016/j.saa.2018.05.031

Abstract

A fast, simple, low cost surfactant-assisted dispersive liquid-liquid microextraction method along with central composite design for the determination of low level of Cr(VI) ions in several aquatic samples has been developed. Initially, Cr(VI) ions present in the aqueous sample were readily reacted with 1,5‑diphenylcarbazide (DPC) in acidic medium through complexation. Sodium dodecyl sulfate (SDS), as an anionic surfactant, was then employed as an ion-pair agent to convert the cationic complex into the neutral one. Following on, the whole aqueous phase underwent a dispersive liquid-liquid microextraction (DLLME) leading to the transfer of the neutral complex into the fine droplet of organic extraction phase. A micro-volume spectrophotometer was used to determine Cr(VI) concentrations. Under the optimized conditions predicted by the statistical design, the limit of quantification (LOQ) obtained was reported to be 5.0 μg/L, and the calibration curve was linear over the concentration range of 5-100 μg/L. Finally, the method was successfully implemented for the determination of low levels of Cr(VI) ions in various real aquatic samples and the accuracies fell within the range of 83-102%, while the precision varied in the span of 1.7-5.2%.

Keywords: Aquatic samples; Central composite design; Cr(VI); Spectrophotometric determination; Surfactant-assisted dispersive liquid-liquid microextraction.