Deep eutectic solvent-induced coacervation in micellar solution of alkyl polyglucoside surfactant: Supramolecular...

The number of deep eutectic solvents were investigated to induce coacervation and cause phase separation in the micellar solution of the alkyl polyglucoside C₈-C₁₀. Three fatty acids were selected as hydrogen bond donors namely hexanoic acid, heptanoic acid, and octanoic acid, while quaternary ammonium salts and a monoterpenoid thymol were used as hydrogen bond acceptors to obtain deep eutectic solvents. The precursors of the deep eutectic solvents could be incorporated into the micelle structure of alkyl polyglucoside C₈-C₁₀ and modulate its properties, improving the interaction with the target compounds and promoting phase separation due to the increasing size of the micellar aggregates. The synergy of green surfactant and deep eutectic solvent has been demonstrated in the determination of capsaicinoids as secondary metabolites retaining the pungency of chili peppers and, thus, of spicy foods. Extraction recoveries were above 75 % for target analytes. The limits of detection were found to be 1.7 μg g ^-1 for capsaicin and dihydrocapsaicin. The relative recoveries were in the range of 76 -130 %. The research presented is the first example of synergy between alkyl polyglucoside and deep eutectic solvent. The proposed extraction system has the potential to be used in many other analytical tasks, especially in the analysis of solid and heterogeneous samples. Not only fatty acid-based deep eutectic solvents but other based on alcohols, monoterpenoids, etc. can also be used for coacervation. Thus, wide range of already studied deep eutectic solvents could be investigated for this purpose.