# Targeted Separation of Ziziphus jujuba Pulp Polyphenols: Adsorption Kinetics Characteristics of AB-8 Resin and Product Structure Analysis

## TL;DR

This study develops an efficient method to purify polyphenols from jujube pulp using a resin-based process and analyzes the resulting compounds.

## Contribution

A novel purification protocol combining DES extraction and AB-8 resin adsorption for high-purity jujube polyphenol isolation is introduced.

## Key findings

- AB-8 resin showed maximum adsorption capacity of 62.48 mg/g and desorption ratio of 83.40%.
- Adsorption followed a pseudo-second-order model, indicating chemisorption mechanism.
- HPLC-MS identified eight key polyphenolic compounds, including chlorogenic acid and quercetin.

## Abstract

To address the challenge of purifying bioactive polyphenols from the complex matrix of Ziziphus jujuba Mill. var. spinosa pulp, this study established an integrated purification protocol combining Deep Eutectic Solvent (DES) extraction with macroporous adsorption resin (MAR) enrichment. Among five screened resins, AB-8 exhibited superior selectivity, achieving a maximum adsorption capacity of 62.48 mg polyphenols/g dry resin and a desorption ratio of 83.40%. Kinetic analysis revealed that the adsorption process strictly followed a pseudo-second-order model (R2 = 0.999), indicating a mechanism dominated by chemisorption. Through dynamic optimization, optimal column parameters were determined as a loading concentration of 2.4 mg/mL, a flow rate of 1.0 mL/min, and elution with 70% (v/v) ethanol. Structural characterization via UV-Vis and FT-IR confirmed the effective removal of polysaccharide and protein impurities, while High-Performance Gel Permeation Chromatography (HPGPC) indicated a low-molecular-weight distribution (Mw approx. 1073 Da). Furthermore, HPLC-MS profiling definitively identified eight key constituents, including chlorogenic acid, catechin, rutin, and quercetin. Collectively, this work elucidates the adsorption mechanism and provides a scalable, efficient technical foundation for the high-purity preparation of jujube polyphenols.