A New Generation of Cloud Point Extraction Methods: Green Solvents, Nanotechnology, and Automation Prospects—A Review
DOI:
https://doi.org/10.64354/ateev533Keywords:
cloud point extraction (CPE); mixed micelles; ionic liquids; deep eutectic solvents; nanomaterials; flow-based extraction; green analytical chemistry; trace analysis.Abstract
Cloud point extraction (CPE) is a micelle-mediated sample-preparation technique that separates and preconcentrates inorganic and organic analytes. Its main advantages include low solvent consumption, simple phase separation, compatibility with spectrometric and chromatographic detection, and the potential for high enrichment factors. However, conventional CPE can require heating, centrifugation, and dilution of the surfactant-rich phase, and some surfactants may interfere with subsequent measurements. Recent developments have therefore focused on mixed-micelle systems, ionic-liquid-assisted CPE, deep eutectic solvent (DES)-assisted rapid synergistic CPE, auxiliary-energy approaches, nanomaterial-assisted extraction, and flow-based or automated formats. This review summarizes the fundamental cloud-point phenomenon and discusses these developments, emphasizing analytical performance, solvent use, extraction time, temperature, and practical limitations. It compares recent applications to trace metals, environmental and food samples, and organic compounds. The review pays particular attention to the important distinction between low volatility and overall environmental safety: ionic liquids and DESs may reduce solvent emissions, but their toxicity, biodegradability, viscosity, and life-cycle impacts must still be assessed. The review also highlights green analytical metrics as useful tools for evaluating the sustainability of CPE procedures. Future progress will depend on integrating greener extraction media with miniaturization, automation, nanotechnology, and robust sustainability assessment.
References
1. Semysim FA, Shabaa GJ, Azooz EA, Snigur D. Alternative green solvents in cloud point extraction methods: recent developments, challenges, and greenness evaluation. Trends in Environmental Analytical Chemistry. 2025;45:e00250. doi:10.1016/j.teac.2024.e00250.
2. Sznek B, Kupczyk O, Czyrski A. Cloud point extraction as an environmentally friendly technique for sample preparation. Processes. 2025;13(2):430. doi:10.3390/pr13020430.
3. Halko R, Hagarová I, Andruch V. Innovative approaches in cloud-point extraction. Journal of Chromatography A. 2023;1701:464053. doi:10.1016/j.chroma.2023.464053.
4. Snigur D, Azooz EA, Zhukovetska O, Guzenko O, Mortada WI, et al. Recent innovations in cloud point extraction towards a more efficient and environmentally friendly procedure. TrAC Trends in Analytical Chemistry. 2023;164:117113. doi:10.1016/j.trac.2023.117113.
5. Mortada WI. Recent developments and applications of cloud point extraction: a critical review. Microchemical Journal. 2020;157:105055. doi:10.1016/j.microc.2020.105055.
6. Gavazov KB, Hagarová I, Halko R, Andruch V. Recent advances in the application of nanoparticles in cloud point extraction. Journal of Molecular Liquids. 2019;281:93–99. doi:10.1016/j.molliq.2019.02.071.
7. Melchert WR, Rocha FRP. Cloud point extraction in flow-based systems. Reviews in Analytical Chemistry. 2016;35(2):41–52. doi:10.1515/revac-2015-0022.
8. Abou El-Reash YG, Algethami FK, Alotaibi AN, et al. A simple mixed-micelle process for selective microextraction of trace Th(IV) from lanthanide matrices. Frontiers. 2025.
9. Gajdošová A, Racheva P, Kiradzhiyska D, et al. Centrifuge-less mixed micelle-mediated cloud point extraction-spectrophotometric determination of vanadium using 4-nitrocatechol and cetylpyridinium chloride. International Journal of Molecular Sciences. 2025.
10. Wannas FA, Azooz EA, Al-Mushhdi AAAH, Naguib IA. Ionic liquid-based cloud point extraction for spectrophotometric determination of copper in water and food samples using a novel imidazole derivative. Journal of Food Composition and Analysis. 2024.
11. Bamdad F, Habibi Z. Surface-active ionic liquid-assisted cloud point extraction for pre-concentration and determination of cobalt ions in pharmaceutical preparations. Iranian Journal of Pharmaceutical Research. 2022.
12. Hagarová I, Andruch V, Kalyniukova A. Green hydrophobic deep eutectic solvent-based rapid synergistic cloud point extraction and quantification of ultra-trace lead. Advances in Sample Preparation. 2025;6:100225. doi:10.1016/j.sampre.2025.100225.
13. Ridha RK, Alasady DH, Azooz EA, Mortada WI. Rapid synergistic cloud point extraction based on hydrophobic deep eutectic solvent combined with hydride generation atomic absorption spectrometry for determination of selenium in tea samples. Journal of Food Composition and Analysis. 2024;132:106286. doi:10.1016/j.jfca.2024.106286.
14. El-Sheik R, Gouda AA, Ibraheem FA, Elgafary M, El Anani LEH. Development of an eco-friendly cloud point extraction method for preconcentration and spectrophotometric determination of copper in environmental samples. Bulletin of the Faculty of Science, Zagazig University. 2025.
15. Bahadır Z, Yazar M, Tümay SO, et al. Development of cloud point extraction preconcentration of cadmium and lead in solid samples using flame atomic absorption spectrometry. Desalination and Water Treatment. 2018.
16. Garoub MM, Gouda AA. An efficient ionic liquid-based cloud point extraction to preconcentrate mercury in environmental samples and hair of occupational workers before spectrophotometric detection. Bulletin of the Chemical Society of Ethiopia. 2022.
17. Abdelwahed FT, Mortada WI, El-Defrawy MM, Eltabey RM. Lead extraction from food samples by combined cloud point–micro solid phase extraction. Journal of Food Composition and Analysis. 2024.
18. Mortada WI, Awad AA, El-Defrawy MM, Khalifa ME. Air-assisted cloud point extraction coupled with inductively coupled plasma optical emission spectroscopy for the determination of samarium in environmental samples. Analytical Sciences. 2022.
19. Semysim FA, Ridha RK, Azooz EA, Snigur D. Switchable hydrophilicity solvent-assisted solidified floating organic drop microextraction for separation and determination of arsenic in water and fish samples. Talanta. 2024.
20. Habbal S, Haddou B, Kameche M, et al. Cloud point or ionic liquid extraction of furfural from aqueous solution: a comparative study based upon experimental design. Desalination and Water Treatment. 2016.
21. Naulapää J, Kangas A, Leino TO, Perea Pérez P, Helttunen K. Cloud point extraction of pyridine N-oxides using mixed micelles of PEGylated calix[4]pyrroles and non-ionic surfactants. RSC Advances. 2025.
22. Wen J, Lu Y, Shi L, Yang Y. A novel cloud point extraction based on fatty acid deep eutectic solvent combined with high-performance liquid chromatography for determination of ultraviolet absorbent in food packaging bags. Microchemical Journal. 2020.
23. Pirdadeh-Beiranvand M, Afkhami A, Madrakian T. Cloud point–magnetic dispersive solid phase extraction for the spectrofluorometric determination of citalopram. Journal of Molecular Liquids. 2017.
24. Baghban N, Haji Shabani AM, Dadfarnia S, Jafari AA. Cloud point extraction of trace amounts of copper and its determination by flow injection flame atomic absorption spectrometry. Croatica Chemica Acta. 2012;85:343–350.
25. El-Bialy NMA, Gouda AA, Ghaith ESIA, Khedr IE, Moustafa AH, Mohamed AEN, et al. Sustainable ionic liquid-assisted cloud point extraction for enrichment of trace copper(II) in water and food samples before spectrophotometric determination. Scientific Reports. 2026;16:18006. doi:10.1038/s41598-026-56689-x.
26. Gajdošová A, Racheva P, Saravanska A, Šandrejová J, Gavazov K. A sensitive cloud point extraction–spectrophotometric determination of vanadium using pyrogallol and Aliquat 336. International Journal of Molecular Sciences. 2026;27(14):6279. doi:10.3390/ijms27146279.
Downloads
Published
Issue
Section
License
Copyright (c) 2026 Chemical Interactions
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
