A centrifuge-less cloud point extraction-spectrophotometric determination of copper(II) using 6-hexyl-4-(2-thiazolylazo)resorcinol

A simple, cheap, and environmentally friendly centrifuge-less cloud point extraction procedure was developed for the preconcentration of traces of Cu(II) before its spectrophotometric determination. It is based on a complexation reaction with the hydrophobic azo reagent 6-hexyl-4-(2-thiazolylazo)resorcinol (HTAR), in which a complex with a stoichiometric ratio of 1:1 and an absorption maximum at 535 nm is formed. The experimental conditions for Cu(II) determination were found: HTAR concentration (8 x 10 (6) mol mL(-1)), mass fraction of the surfactant Triton X-114 (2.2%), pH (5.9, ammonium acetate buffer), and incubation time (10 min at 60 degrees C). The linear range, limit of detection, molar absorption coefficient and preconcentration factor were calculated to be 4.5-254 ng mL(-1), 1.34 ng mL(-1), 2.54 x 10(5) L mol(-1) cm(-1), and 10, respectively. The effect of foreign ions was studied, and the proposed procedure was applied to the analysis of water samples and a saline solution for intravenous infusion. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A simple, cost-effective, and environmentally friendly cloud point extraction method was developed to concentrate traces of Cu(II) for spectrophotometric determination. The method is based on a complexation reaction with the hydrophobic azo reagent HTAR, with specific experimental conditions determined for optimal Cu(II) determination. The proposed procedure was successfully applied to water samples and saline solution analysis, showing practical value in real-world applications.