Profiling and evaluation of phenolic compounds in olive mill wastewater in Jordan

Abstract

Phenolic compounds (PCs) are prevalent in olive mill wastewater (OMW), offering numerous health benefits but concurrently posing environmental challenges. This study aims to comprehensively characterize PCs in OMW, both qualitatively and quantitatively. We have successfully developed an accurate, sensitive, and cost-effective method for extracting and quantifying seven PCs in OMW. The extraction procedure was optimized to achieve the highest recovery through the adaptation of a liquid–liquid extraction method. The concentrations of the identified PCs were determined using a high-performance liquid chromatography-diode array detector (HPLC-DAD). Successfully separated on an RP-C8 column within a 23-min runtime, the seven peaks were eluted by employing a gradient mobile phase. The method underwent thorough validation, producing satisfactory results. Subsequently, the developed method was applied to analyze OMW from four olive mills in Jordan. Revealing PC concentrations ranging from 139 to 430 mg/L, tyrosol and hydroxytyrosol were identified as the most abundant compounds. Additionally, gas chromatography–mass spectrometry (GC–MS) was used to separate and identify 40 PCs. The total phenolic content was also quantified and found to be 1,839 mg/L. Moreover, the antioxidant activity was assessed, yielding a maximum value of 95.8%. These results underscore the substantial levels of PCs in OMW, highlighting the importance of economically utilizing this water.