مشخصات پژوهش

In this study, the challenge of extracting the hydrophilic drug losartan potassium (LP) from human plasma was successfully addressed using a switchable deep eutectic solvent (SDES) composed of tetrabutylammonium bromide and nonanoic acid at a molar ratio of 1:3, capable of reversible polarity modulation via pH adjustment. This sustainable analytical strategy enabled efficient phase transfer of the polar analyte, overcoming limitations of conventional extraction techniques for hydrophilic compounds. Because maximum fluorescence of LP occurs in acidic media, a back-extraction (BE) step was incorporated to ensure accurate spectrofluorometric determination. Accordingly, an ultrasound-assisted liquid-phase microextraction (UA-LPME) method based on SDES, followed by BE, was developed. The method integrates simplified sample preparation, reduced organic solvent consumption, and optimized operational conditions to minimize environmental impact without compromising analytical performance. Key variables were optimized individually and through central composite design with a desirability function approach. The method exhibited a linear range of 50–1250 ng/mL, a limit of detection of 15.6 ng/ mL, precision with RSD values below 7%), and an extraction recovery of 60.9%, along with satisfactory relative recoveries in real plasma samples. Sustainability was objectively assessed using ComplexMoGAPI and benchmarked against previously reported procedures. The proposed method achieved the highest overall greenness score (83), reflecting reduced solvent usage, lower hazard profile, simplified workflow, and improved energy efficiency. The use of spectrofluorometric detection, which eliminates continuous mobile phase consumption and reduces energy demand, further enhances the environmental performance. This method represents an environmentally responsible alternative for routine pharmaceutical analysis.