The application of three-phase solvent bar microextraction based on a deep eutectic solvent coupled with high-performance liquid chromatography for the determination of flavonoids from vegetable and fruit juice samples
In the present study, a new three-phase solvent bar microextraction based on a deep eutectic solvent (SBME-DES) was developed for the preconcentration and extraction of quercetin (Qu) and morin (Mo) from vegetable and fruit juice samples. In this process, the target analytes were extracted from an aqueous sample into 1-undecanol as the carrier impregnated in the pores of a hollow fiber, and then back-extracted into a mixture of hydrophilic DES (tetramethylammonium chloride : ethylene glycol) and methanol was applied as the acceptor phase in SBME. The experimental results show that the efficiency of this method with the use of DES is higher than that with conventional solvents. Important extraction parameters such as the nature of the supported liquid membrane (SLM), composition of the deep eutectic solvent, pH, stirring rate, extraction time, and ionic strength were investigated and optimized. The analysis of the extracted analytes was performed via high-performance liquid chromatography coupled with an ultraviolet detector. Under the optimal conditions, linearity was observed in the range of 1–500 ng mL−1 for morin and 10–500 ng mL−1 for quercetin. The extraction recoveries obtained were in the range of 90–94%, precision (relative standard deviation) (n = 3) below 3.6% and limit of detection in the range of 0.2–2.6 ng mL−1. Finally, the new method was successfully applied for the preconcentration of morin and quercetin in onion and fruit juice samples.