Novel Salt-Assisted Liquid-Liquid Microextraction Technique for Environmental, Food, and Biological Samples Analysis Applications: A Review

Abstract

Background:: Sample preparation has gained significant recognition in the chemical analysis workflow. Substantial efforts have been made to simplify the comprehensive process of sample preparation that is focused on green sample preparation methodology, including the miniaturization of extraction method, elimination of the sample pre-treatment as well as the post-treatment steps, elimination of toxic as well as hazardous organic solvent consumption, reduction in sample volume requirements, reducing the extraction time, maximization of the extraction efficiency and possible automation. Methods:: Among various microextraction processes, liquid-phase microextraction (LPME) is most abundantly used in the extraction of the target analytes. The salting-out phenomenon has been introduced into the LPME procedure and has been raised as a new technique called the ‘Salt-Assisted Liquid-Liquid Microextraction (SALLME)’. The principle is based on decreasing the solubility of less polar solvent or analyte with an increase in the concentration of the salt in aqueous solution leading to two-phase separation. Conclusion:: SALLME proved to be a simple, rapid, and cost-effective sample preparation technique for the efficient extraction and preconcentration of organic and inorganic contaminants from various sample matrices, including environmental, biological, and food samples. SALLME exhibits higher extraction efficiency and recovery and compatible with multiple analytical instruments. This review provides an overview of developments in SALLME technique and its applications to till date.

Simultaneous determination of six catechins and caffeine in tea and wine using salting‐out assisted liquid–liquid extraction and high‐performance liquid chromatography with ultraviolet detection

“…A green tea sample was chosen to optimize the SALLE procedure. The SALLE technique involves adding a high concentration (up to 30%) of an inorganic salt to disrupt the solvation of target compounds and reduce their solubility in the aqueous phase [25]. This induces phase separation, facilitating the extraction, and purification of target compounds from complex sample matrices.…”

“…Meanwhile, solid-phase extraction and matrix solid-phase dispersion ensure selective purification [23]. Salting-out assisted liquid-liquid extraction (SALLE) is widely used in food analysis to extract and concentrate analytes of interest from complex food matrices [24,25]. The process involves adding a high concentration of water-miscible salt to the sample, which reduces the solubility of the analytes in the aqueous phase and promotes their partitioning into an immiscible organic solvent [24].…”

“…The process involves adding a high concentration of water-miscible salt to the sample, which reduces the solubility of the analytes in the aqueous phase and promotes their partitioning into an immiscible organic solvent [24]. This partitioning occurs due to the differences in solubility of the analytes in the presence of the salt, leading to the formation of two separate phases [25]. The organic phase, containing the target analytes, is collected, and then evaporated to yield a concentrated sample suitable for further analysis [26].…”

“…The organic phase, containing the target analytes, is collected, and then evaporated to yield a concentrated sample suitable for further analysis [26]. Its simplicity, effectiveness, and compatibility with various analytes make it an essential tool in food analysis for determining the composition and quality of different food products [24][25][26].…”

Salt-Induced Homogeneous Liquid–Liquid Microextraction of Piroxicam and Meloxicam from Human Urine Prior to Their Determination by HPLC-DAD

“…Moreover, HLLME overcomes the need for analyte back-extraction due to the compatibility of the solvent with most chromatographic systems [21]. Common types of HLLME include the saltinduced HLLME (SI-HLLME) [24] and the sugar-induced HLLME [25], in which phase separation is achieved by the addition of salts and sugars, respectively. Other paths for the induction of the formation of the extractant phase include the reduction in temperature, the introduction of small amounts of hydrophobic solvents, the addition of buffer solutions for the acidification of the sample solution and the introduction of aprotic solvents [21,23].…”