Salting-out assisted liquid-liquid extraction (SALLE): Principle , optimization, and applications in blood sample analysis

This review focuses on the use of Salting-Out Assisted Liquid-Liquid Extraction (SALLE) for blood sample processing prior analysis, exploring its principles, optimization parameters, and coupling with analytical techniques. SALLE is favored for its simplicity, cost-effectiveness, and rapid execution using the salting-out effect to induce phase separation in mixtures of aqueous samples and water-miscible organic solvents. The review categorizes and discusses the different types of blood samples, the main salts and solvents used, and the parameters affecting the extraction efficiency, such as solvent and salt type as well as ionic strength, pH, vortex mixing and centrifugation time. Advantages of SALLE over traditional methods like solid-phase extraction (SPE) and protein precipitation (PP) are highlighted, emphasizing its environmental friendliness, high extraction efficiency, and ease of automation. By examining recent literature and scientific publications (2014-2024), this review provides a comprehensive understanding of the factors influencing SALLE performance and its application in bioanalysis, particularly when coupled with separative techniques such as liquid chromatography (LC), capillary electrophoresis (CE), and mass spectrometry (MS).