Chromium speciation using task specific ionic liquid/aqueous phase biphasic system combined with flame atomic absorption spectrometry

• Published in: Journal of molecular liquids 2016-09, Vol.221, p.798-804
• Main Authors: Sadeghi, Susan, Moghaddam, Ali Zeraatkar
• Format: Article
• Language: English
• Subjects: Central composite design; Chromium speciation; Flame atomic absorption spectrometry; IL/aqueous phase biphasic system; Salicylate based ionic liquid
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2016.06.056

In this work, 1-alkyl-3-methylimidazolium based ionic liquids combined with salicylate or thiosalicylate anions as task specific ionic liquids were used to form a stable ionic liquids (IL)/aqueous biphasic systems for extraction of Cr(III) and Cr(VI) species prior to flame atomic absorption spectrometry (FAAS) determination. It was found that the 1-octyl-3-methylimidazolium salicylate was selective to extract Cr(III). The Cr(VI) content was calculated by subtracting Cr(III) from the total chromium with conversion of Cr(VI) to Cr(III) in the presence of ascorbic acid. Based on the preliminary experiments, the factors influencing phase behavior of the IL/aqueous biphasic system were investigated. The main factors affected the extraction of Cr(III) were modeled by using central composite design and optimized by using non-linear Nelder-Mead method. Under the defined optimum conditions, the calibration curves were linear over the concentration range of 40–470μgL−1 and 55–500μgL−1 for Cr(III) and total Cr, respectively. The limit of detection (3Sb/m) for Cr(III) was 7.7μgL−1. The relative standard deviations for six replicate determinations of 250μgL−1 of Cr(III) and total Cr were 5.5% and 7.6%, respectively. Finally, the proposed system has been successfully applied to the extraction and speciation of Cr in real water and urine samples. •The alkyl derivative-3-methyl imidazolium based task specific ionic liquids were used to prepare ABS.•The 1-octyl-3-methylimidazolium salicylate was found selective to extract Cr(III) in biphasic system.•The Cr(VI) content was obtained by subtraction of Cr(III) content from total Cr.•The main factors affected the extraction of Cr(III) were modeled by using central composite design.•The proposed system applied to the extraction and speciation of Cr in real water and urine samples