title: Cloud point extraction of Cu(II) using a mixture of Triton X-100 and dithizone with a salting-out effect and its application to visual determination.
abstract: A method for the separation and concentration of trace copper(II) ion (Cu(II)) via cloud point extraction (CPE) using a nonionic surfactant with a salting-out effect was developed and applied as a technique for the visual determination of Cu(II). Triton X-100 (TX-100), which has a cloud point at 64-67 °C in aqueous solutions, was used as the nonionic surfactant for the CPE of Cu(II). Although CPE with TX-100 requires heating of the solution to separate the surfactant-rich phase from the aqueous phase, the new method achieves phase separation at 15-30 °C owing to the addition of a large amount of salt to the solution, which lowers the cloud point. The compound 1,5-diphenylthiocarbazone (dithizone) was selected as the chelating agent for complexation and transfer of Cu(II) to the surfactant-rich phase. The extractability of Cu(II) (initial concentration: 10 μM) was 96.6±2.1% when Na2SO4 was added to a 20% TX-100/4 μM dithizone solution (pH 2). Using this method, the visual determination of Cu(II) was possible for concentrations ranging from 0.01 to 10 μM. In addition, the extraction system was successfully applied to the visual determination of Cu(II) in a river water sample.
authors.affiliation: Faculty of Science and Technology, Gunma University, 1-5-1, Tenjin-cho, Kiryu, Gunma 376-8515, Japan.
authors.forename: Nobuko
authors.initials: N
authors.lastname: Sato
authors.forename: Masanobu
authors.initials: M
authors.lastname: Mori
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Itabashi
mesh_terms: D002413:Cations, Divalent; D003116:Color; D003124:Colorimetry; D003300:Copper / Q000302:isolation & purification*; D004230:Dithizone / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D017830:Octoxynol / Q000737:chemistry*; D045483:Rivers / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013431:Sulfates / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D002413:Cations, Divalent; D013431:Sulfates; D013501:Surface-Active Agents; D014874:Water Pollutants, Chemical; C012036:sodium sulfate; D004230:Dithizone; D003300:Copper; D017830:Octoxynol
keywords: Cloud point extraction; Copper ion; Salting-out effect; Triton X-100; Visual determination