Optimization of ultrasonication-assisted extraction conditions using RSM-I-Optimal experimental design to recover vitamin D(2) and K(1) from selected green leafy vegetable samples

This study employed the response surface methodology to optimize the extraction conditions for recovering vitamins D(2) and K(1) from green leafy vegetables using ultrasonication-assisted extraction. The vitamin content was determined using an Accucore C18 column and a UPLC-Q-ToF/MS method. An RSM-I-Optimal design was used for designing the experiment to find the best combination of solvent level (mL), sonication time (min), sonication frequency (kHz), and temperature (°C). The experimental data from a 25-sample set were fitted to a second-order polynomial equation using multiple regression analysis. The extraction models had R(2) values of 0.895 and 0.896, respectively, and the probability values (p < 0.0001) indicated that the regression model was highly significant. The optimal extraction conditions were: solvent level of 65 mL, sonication time of 45 min, sonication frequency of 70 kHz, and temperature of 45 °C. Under these conditions, the predicted recovery (%) values for vitamins D(2) and K(1) were 90.7% and 90.4%, respectively. This study has the potential to use the reported extraction method for routine quantification of vitamins D(2) and K(1) in the laboratory using UPLC-Q-ToF/MS.