Hydrophobic Deep Eutectic Solvents as New Supported Liquid Membranes for Extraction of β-Blockers by Hollow Fiber–Electromembrane Extraction

In this work, an electromembrane extraction method is presented to extract some β-blockers in biological samples. A new hydrophobic deep eutectic solvent, as a green solvent, was synthesized. The hydrophobic deep eutectic solvent was immobilized in the wall pores of the hollow fiber membrane and used as a supported liquid membrane. β-Blockers were transported from the sample solution through an SLM, including tris-(2-ethylhexyl) phosphate, into the acceptor phase located in the lumen of the hollow fiber. High-performance liquid chromatography with ultraviolet detection has been used to separate and analyze the β-blockers. Effective parameters on the extraction efficiency of the β-blockers such as hydrophobic deep eutectic solvent molar ratio (2:1), extraction voltage (75 V), type of ion carrier and its concentration (tris-(2-ethylhexyl) phosphate, 5%), pH of donor and acceptor phases (ultrapure water and 100 mM of HCl), hollow fiber length (7 cm), extraction time (20 min), stirring speed of sample solution (600 rpm), and salt effect (0%) were investigated and optimized. The method provides a decent linearity by the coefficient of determination values higher than 0.9946. Limits of detection were in the range of 0.25–3.3 ng mL⁻¹, and limits of quantification were found in the range of 0.75–10.0 ng mL⁻¹ in water. Finally, the method was successfully used to determine the β-blockers concentrations in real urine and plasma samples with relative recoveries between 90.6% and 108.6%.