Hollow Fiber-Based Liquid Phase Microextraction Combined with Chemometrics Approach: Determination of Rosmarinic Acid in Lavandula angustifolia Products

Lavandula angustifolia (lavender) is among the most practical and widely employed medicinal plants. Rosmarinic acid constitutes a fundamental constituent of lavender. This study centers around the extraction of rosmarinic acid from prepared lavender extract using hollow fiber-based liquid phase microextraction with acetonitrile as an extractant. The optimization of extraction factors, such as the initial and extraction solvent pH, and extraction time, is achieved through the application of a chemometric method. Additionally, the quantification of rosmarinic acid in samples of commercial herbal medicines is also investigated. The results obtained from the experimental design analysis revealed that the initial solvent pH had a statistically significant impact on the efficiency of rosmarinic acid extraction (p-value < 0.0001). Furthermore, the efficiency remains unaffected by the extraction time (p-value 0.5464). In order to obtain a significant value for the rosmarinic peak area as a response, the extraction solvent pH was set to 3.17, and the extraction time was set to 17.32 min. The optimized procedure demonstrated linearity in the range of 0.5 to 200 μg/g; the determination coefficient, limits of detection, and quantification were, respectively, 0.9998, 015, and 0.5 μg/g. Consequently, it was determined that each sample of the herbal medicines contained rosmarinic acid.