Sustainable and Innovative Method for Real-Time Extraction and Analysis of Polyphenols from Green Propolis by Pressurized Liquid Extraction Coupled Inline with Photodiode Array Detection (PLE-PDA)

This article proposes an innovative process for extracting green propolis polyphenols, integrating real-time monitoring while adhering to green practices. This development is significant due to the complex propolis composition that requires extensive extraction and analytical methods, leading to an environmental impact. The study employed pressurized liquid extraction (PLE) combined with photodiode array detection (PDA) to simultaneously recover and quantify polyphenolic compounds from green propolis. The process was fully optimized regarding operational extraction variables, specifically the solvent-to-feed ratio, solvent composition, and temperature. An exhaustive extraction was achieved using ethanol as solvent, at 130 °C, 2 mL·min–1 solvent flow rate, and 1500 psi, resulting in a total polyphenolic content of 148 mg·gpropolis–1 in 35 min. Additionally, the ability to quantify the signal obtained by the PDA represents a significant advancement in real-time monitoring processes, reducing the need for toxic solvents typically required in offline chromatographic analysis and shortening extraction times. The optimized method achieved a high green analytical score of 0.9 (AGREE) and a Path2Green score of 0.477, demonstrating strong adherence to the 12 principles of green analytical chemistry and green extraction, respectively. Also, high Blue Applicability Grade Index (BAGI) of 85.0 is present, demonstrating great practicality and applicability of the method. This work highlights an innovative technique, opening new perspectives for future innovations, even when complex matrices are studied.