Phase formation in sodium dodecylsulfate solutions in the presence of salicylic acid for preconcentration purposes

Abstract

The occurrence of surfactant-rich phases in aqueous sodium dodecylsulfate solutions in the presence of salicylic acid was investigated. The effect of acidity, electrolyte and salicylic acid concentrations on the parameters of phase formation were studied. Optimal conditions for microcomponent preconcentration were found. The features of solubilization efficiency changes of organic substances depending on their charge and hydrophobicity were established. High efficacy of preconcentration of strongly hydrophobic, positively charged substrates by low-temperature surfactant-rich phases obtained in the sodium dodecylsulfate-salicylic acid-sodium chloride ternary system is shown.

Hydrotrope-Induced Micellar Phase of Sodium Dodecyl Slfate as New Detergent for Extraction and Stabilization of Proteins

“…1). This liquid phase exists until the molecular form of hydrotrope dominates (pH < pK f HSal < 4) [5,7]. Table 1 shows the changes of composition of SDS phase in response to variations of components concentration in start micellar solution.…”

“…Nowadays, micelle extraction is a widely-used approach of environmentally benign extraction of protein substrates, that easily combines with various detection and separation techniques [5,6]. It may be caused by high capacity of micelle-forming detergents to efficient cell lysis and quantitative extraction of macromolecules that have both hydrophobic and hydrophilic domains [3].…”

“…Phase separation of the micellar solutions that occurred due to some temperatures changes and addition of hydrotropes or electrolytes improves proteins solubilization [5]. Generally, water-soluble proteins stay in solution but hydrophobic substrates precipitate with micellar phase [3,4].…”

“…Unfortunately, the application of SDS solution can lead to denaturation of protein and loss of its activity [3,4]. In addition, the volumetric crystalline SDS phases which formed at the temperature below the Kraft point (T K ) and at the presence of electrolytes are characterized by low degree of proteins extraction [5,7]. Nevertheless, previously we established that compact liquid micellar phase can be formed from mixtures of SDS and modifying additives of sodium chloride and salicylic acid (HSal) at the temperatures of approximately 298-303 K. Unlike the majority of extraction systems this phase is able to effectively extract the proteins of different nature not only at isoelectric point (pI) but also in the conditions of proteins cationic forms domination pH ≤ pI [6][7][8].…”

Sensitive ergotamine determination in pharmaceuticals and biological samples using cloud point preconcentration and spectrofluorimetric detection

“…Cloud point phenomena have been achieved typically for aqueous solutions of some nonionic surfactants. Even though some authors have proposed the use of ionic surfactant solutions as an alternative to the conventional nonionic surfactants for the preconcentration of charged substances [25], the use of the sodium dodecyl sulphate (SDS) for CPE of ergotamine was inadequate. Unlike nonionic surfactants systems, phase separation of SDS solution is induced by the presence of high levels of inert salts.…”