Comparison of Methods for the Study of Ellagic Acid in Pomegranate Juice Beverages

摘要

The present study aims to compare two kinds of methods to detect and quantify ellagic acid in commercial pomegranate beverages. Constant-wavelength synchronous spectrofluorimetry and high-performance liquid chromatography have been used for the study, and high-performance liquid chromatography photo diode array mass spectrometry has been used as a confirmatory technique. Ellagic acid is a polyphenol with strong antioxidant capacity which confers its numerous health benefits. Spectroflurometric is the most sensitive method (LOD = 0.021 μg/mL; LOQ = 0.024 μg/mL) in comparison with high-performance liquid chromatography (HPLC) (LOD = 0.079 and LOQ = 0.097 μg/mL), and it takes also less time to perform. The obtained results for ellagic acid concentration differ in the two studied methods; the reason could be that other compounds are detected at the same wavelength (λ ex = 383 nm) than the ellagic acid in the constant-wavelength synchronous spectrofluorometry. Among these compounds was the punicalagin which is the most important ellagitanin present in the pomegranate beverages and the hydroxicinnamic acids. Therefore, it was concluded that the most suitable method to quantify ellagic acid was HPLC-UV, and the confirmation by HPLC-MS/MS. On the other hand, constant-wavelength synchronous spectrofluorimetry is considered as a good alternative method in the ellagitannins detection in juices and beverages, since it give us an idea of the juice antioxidant power.