Development of sodium hydroxide-induced homogenous liquid-liquid extraction-effervescent assisted dispersive liquid-liquid microextraction based on deep eutectic solvents; Application in the extraction of phytosterols from cow cream samples

Abstract

In this study, sodium hydroxide-induced homogenous liquid-liquid extraction was combined with effervescent assisted-dispersive liquid-liquid microextraction and used for the extraction of phytosterols (lupeol, β-sitosterol, stigmasterol, campesterol, and brassicasterol) from cream samples. Two types of deep eutectic solvents (water-miscible and water-immiscible solvents) were prepared and used in the extraction procedure. In this approach, firstly, the sample was dissolved in a mixture of n-hexane and tetrabutylammonium bromide: ethylene glycol deep eutectic solvent (as extraction/disperser solvent) and a homogenous solution was obtained. After that, a few microliters of sodium hydroxide solution (as fatty acid saponification and phase separation agent) was quickly injected into the mixture. By doing so, a three-phase system was formed. Then, the supernatant phase (tetrabutylammonium bromide: ethylene glycol deep eutectic solvent) was removed and mixed with tetrabutylammonium bromide: dichloroacetic acid: octanoic acid deep eutectic solvent. The obtained solution was applied in the microextraction step. To obtain effective, reliable, robust, accurate, and precise analytical results, the effective parameters for the presented method were investigated and optimized in detail. Detection limits, extraction recoveries, and enrichment factors were in the ranges of 0.06–0.26 μg kg–1, 86–93 %, and 215–232, respectively. Intra- and inter-day repeatabilities were investigated at a concentration of 1.5 μg kg–1 (each analyte) and they were in the ranges of 5.3−7.5 and 7.2–8.8 %, respectively. Finally, the presented method was easily used in determination of the phytosterols in cow milk cream samples.