The macroporous adsorption resins were used to enrich the walnut pellicle polyphenols and the separation process conditions were optimized, the phenolic compounds were then identified. The results showed that the AB-8 resin was the ideal resin for enriching crude walnut pellicle polyphenols. The ideal enrichment parameters were as follows: sample concentration was 2.00 mg/mL at pH 3.0 with the static adsorption time for 3 h, meanwhile 70% ethanol was used as the eluent solvent. Dynamic adsorption study showed that the maximum loading amount was 14 BV and the amount of eluent was 4 BV. Under above conditions, the purity of walnut pellicle polyphenols was increased from 24.24% to 70.52%. The walnut pellicle polyphenols were identified using the Ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UPLC-TOF-MS/MS). There were more than 30 kinds of polyphenols compounds were tentatively identified including ellagic acid, HHDP-glucose isomer, Di-HHDP-glucose, trigalloyl-HHDP glucose, teragalloyl-glucose, casuarinin/casuarinin isomer, glansrin C isomer, ellagic acid hexose isomer, ellagic acid pentose isomer, glansreginin A. This research indicates that macroporous adsorption resin could act as a preliminary separation media for refined walnut polyphenols containing mainly ellagic acid and its derivatives.
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