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Abstract
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Liquid-phase microextraction (LPME) undoubtedly constitutes one of the most exploited strategies within modern analytical microextraction methods for sample preparations. Since the incorporation of the Green Analytical Chemistry guidelines in the sample preparation stage, the search for new solvents to improve the environmentally friendliness of LPME methods is one of the most important research lines in the field [1]. Deep eutectic solvents (DESs) have attracted attention in recent years as new green solvents. These solvents have properties like ionic liquids, with the advantage of presenting low-cost and straightforward synthesis. The production of DESs requires low-cost raw materials from renewable sources, which makes them alternative solvents of great interest for applications in extraction processes [2]. In this study, a new DES by combining various fatty acids which can concurrently act as both hydrogen bond acceptors (HBA) and hydrogen bond donors (HBD) was prepared. Adding a third component to classical two-component eutectic solvents allows to purposefully control the density, melting point, and viscosity of the synthesized solvents. The DES was used as an extraction solvent in the ultrasound-assisted emulsification-microextraction (USAEME) of amlodipine in plasma samples. Accurate and sensitive determination of amlodipine was accomplished with the combination use of USAEME-based DES and UV-Vis spectrophotometric detection. The central composite design combined with the desirability function was applied to find out the optimal experimental conditions providing the highest global extraction efficiency. The effect of important analytical variables such as pH of sample solution, the volume of the DES, amount of added salt, and sonication time was studied and optimized. According to the optimization criteria, the experimental conditions according to the maximum one in the desirability function were found to be: pH = 9.46; DES volume, 126 μL; NaCl, 16.69% (w/v)
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