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Updated: Sep 3, 2025

Extraction and Characterization of Surfactants from Atmospheric Aerosols
Published on: April 21, 2017
Use of a Hydrophobic Azo Dye for the Centrifuge-Less Cloud Point Extraction-Spectrophotometric Determination of
Kiril Blazhev Gavazov1, Petya V Racheva1, Nikolina P Milcheva1
1Department of Chemical Sciences, Faculty of Pharmacy, Medical University of Plovdiv, 120 Buxton Bros Str., 4004 Plovdiv, Bulgaria.
Abstract:
The hydrophobic azo dye 6-hexyl-4-(2-thiazolylazo)resorcinol (HTAR, H2L) was studied as part of a system for the centrifuge-less cloud point extraction (CL-CPE) and spectrophotometric determination of traces of cobalt. The extracted 1:2 (Co:HTAR) complex, [CoIII(HL-)(L2-)]0, shows an absorption maximum at 553 nm and contains HTAR in two different acid-base forms. Optimum conditions for its formation and CL-CPE were found as follows: 1 × 10-5 mol L-1 of HTAR, 1.64% of Triton X-114, pH of 7.8, incubation time of 20 min at ca. 50 °C, and cooling time of 30 min at ca. -20 °C. The linear range, limit of detection, and apparent molar absorptivity coefficient were 5.4-189 ng mL-1, 1.64 ng mL-1, and 2.63 × 105 L mol-1 cm-1, respectively. The developed procedure does not use any organic solvents and can be described as simple, cheap, sensitive, convenient, and environmentally friendly. It was successfully applied to the analysis of artificial mixtures and real samples, such as steel, dental alloy, rainwater, ampoules of vitamin B12, and saline solution for intravenous infusion.
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