Nouran A. Hamed

Bio: Nouran A. Hamed is an academic researcher from Tanta University. The author has contributed to research in topics: Micelle & Critical micelle concentration. The author has an hindex of 2, co-authored 3 publications receiving 6 citations.

Spectroscopic methods for determination of critical micelle concentrations of surfactants; a comprehensive review

Abstract: The applications of surfactants in various fields are gaining more attention, which makes full characterization of surfactants of growing interest. It is fundamental to measure the critical micelle...

Simple Spectrophotometric Method to Measure Surfactant CMC by Employing the Optical Properties of Curcumin’s Tautomers

Abstract: Surfactants or surface-active agents are interesting groups of compounds with characteristic structures, allowing them to decrease the surface tension. A surfactant consists of a hydrophilic head and a hydrophobic tail. Typically, surfactant molecules aggregate into micelles at the critical micelle concentration. In this work, the concept of tautomerism has been successfully used for the determination of the critical micelle concentration of cetyltrimethylammonium bromide using curcumin as a colored probe. The ratio between diketo and keto–enol tautomers of curcumin increases by increasing the concentration of cetyltrimethylammonium bromide above the critical micelle concentration. This ratio can be monitored by measuring the absorbance ratio at Aλ360/Aλ428nm. The critical micelle concentration of cetyltrimethylammonium bromide was obtained from the inflection in the curve and was found to be 0.76 mM which agrees with the reported value.

Spectroscopic methods for determination of critical micelle concentrations of surfactants; a comprehensive review

Abstract: The applications of surfactants in various fields are gaining more attention, which makes full characterization of surfactants of growing interest. It is fundamental to measure the critical micelle...

Homogeneous liquid–liquid extraction as an alternative sample preparation technique for biomedical analysis

Abstract: Liquid-liquid extraction is a widely used technique of sample preparation in biomedical analysis. In spite of the high pre-concentration capacities of liquid-liquid extraction, it suffers from a number of limitations including time and effort consumption, large organic solvent utilization, and poor performance in highly polar analytes. Homogeneous liquid-liquid extraction is an alternative sample preparation technique that overcomes some drawbacks of conventional liquid-liquid extraction, and allows employing greener organic solvents in sample treatment. In homogeneous liquid-liquid extraction, a homogeneous phase is formed between the aqueous sample and the water-miscible extractant, followed by chemically or physically induced phase separation. To form the homogeneous phase, aqueous samples are mixed with water-miscible organic solvents, water-immiscible solvents/cosolvents, surfactants, or smart polymers. Then, phase separation is induced chemically (adding salt, sugar, or buffer) or physically (changing temperature or pH). This mode is rapid, sustainable, and cost-effective in comparison with other sample preparation techniques. Moreover, homogeneous liquid-liquid extraction is more suitable for the extraction of delicate macromolecules such as enzymes, hormones, and proteins and it is more compatible with liquid chromatography with tandem mass spectrometry, which is a vital technique in metabolomics and proteomics. In this review, the principle, types, applications, automation, and technical aspects of homogeneous liquid-liquid extraction are discussed.