Development, optimization and comparison of solid-liquid and liquid-liquid microextraction for the determination of...

Flavonoids are particularly interesting because they have a broad spectrum of biological effects, including antioxidant and free radical scavenging activities. In this work, solid-liquid microextraction and dispersive liquid-liquid microextraction enhanced by ultrasound were developed and compared with the conventional method (Soxhlet extraction) to optimize the extraction of four flavonoids: rutin, quercitrin, quercetin, and myricetin in samples of Schinus molle (Aguaribay). During the development of the analytical method, different chemometric tools were used to optimize the microextraction procedure. In addition, an analytical method based on high-performance liquid chromatography with diode array detector (HPLC-DAD) and second order calibration using multivariate curve resolution-alternating least square (MCR-ALS) is presented to quantify the flavonoids with limits of quantification between 0.011 and 0.082 µg mL^-1. Finally, solid-liquid microextraction using 4.00 mL water/ethanol (54.3:45.7%), 14 s vortex, and 45 min was selected as the most suitable method due to its high recovery rate and environmental friendliness (with a greenness score of 0.78). After the optimization step, the concentrations found in the plant samples were 1825.3, 632.6, 110.2, and 18.9 µg g^-1 for rutin, quercitrin, quercetin, and myricetin, respectively. The present work is the first achievement of simultaneously determining these four analytes with exceptional sensitivity, demonstrating lower LOQs compared to previous reports.