Optimization of solid-phase extraction for recovering phenolic compounds from NADES-based olive pomace extracts: A comparison of different copolymeric sorbents and conditioning/desorption conditions

Olive oil is delicious—but its production leaves a bitter waste problem. Now, scientists are turning olive pomace into a goldmine of antioxidants using green chemistry.

Every drop of olive oil comes with a hidden cost: mountains of olive pomace, a by-product that poses serious environmental challenges. But this waste may hold a treasure trove of phenolic compounds—natural antioxidants with proven health benefits. The challenge? Extracting them efficiently without harming the planet.

In this study, researchers used solid-phase extraction (SPE) to purify phenolics from olive pomace extracts prepared with natural deep eutectic solvents (NADES), a green alternative to conventional solvents. They tested five different SPE cartridges under various conditioning and desorption protocols, including eco-friendly solvent strategies.

The results were striking. Solvent polarity and pH played a critical role, with acidified desorption significantly improving compound elution. The C18 and HLB cartridges, especially when paired with ethanol or methanol acidified with 2% acetic acid, achieved the highest total recovery—exceeding hydroethanolic extracts by more than 50%.

Even better, specific sorbent–solvent combinations allowed selective enrichment of valuable compounds like hydroxytyrosol, verbascoside, and demethyloleuropein. This approach offers a powerful, green pathway to recover and concentrate bioactive phenolics from natural matrices, turning waste into wellness.

Key Points

• NADES extraction plus SPE purifies olive pomace phenolics.
• Acidified desorption boosts recovery; C18 and HLB best.
• Green method recovers >50% more than hydroethanolic extracts.