title: Environmentally friendly and non-polluting solvent pretreatment of palm samples for polyphenol analysis using choline chloride deep eutectic solvents.
abstract: In this work, choline chloride (ChCl) deep eutectic solvents (DESs) were evaluated for the pretreatment of palm samples in the analysis of polyphenols, such as protocatechuic acid, catechins, epicatechin, and caffeic acid. During the enrichment step of the pretreatment, eight DESs comprising ChCl with ethylene glycol (EG), glycerol (Gly), xylitol (Xyl), phenol (Ph), formic acid (FA), citric acid (CiA), oxalic acid (OA), or malonic acid (MA), were prepared and applied to the reflux extraction of polyphenols from palm samples. All the DESs exhibited higher polyphenol extraction efficiency than methanol, and the highest extraction efficiency was obtained using ChCl-FA (1:1, mole ratio). For the purification step of the pretreatment, eight ChCl DES-modified adsorbents were prepared by hydrothermal polymerization and packed into solid-phase extraction (SPE) cartridges, and ChCl-Urea, ChCl-Gly, ChCl-FA, and water, were used as eluents. The ChCl DES-modified adsorbents were characterized by Fourier transform infrared spectroscopy, thermal gravimetric analysis, scanning electron microscopy, and Brunauer-Emmett-Teller surface analysis, and the polyphenols were analyzed by mass spectrometry and high-performance liquid chromatograph-ultraviolet detection. The highest purification efficiency was obtained using the ChCl-Ph DES-modified adsorbent as the SPE packing material and ChCl-Urea-H2O (1:1:5, mole ratio), ChCl-Gly (1:1, mole ratio), ChCl-FA-H2O (1:1:5, mole ratio), and H2O as the eluents. Compared to conventional purification processes that employ commercial C18or C8SPE columns with organic solvents as eluents, the ChCl DES-based SPE purification process successfully avoided the use of expensive commercial SPE columns and organic solvents. Furthermore, it isolated a larger amount of the target compounds under the same experimental conditions, and could be applied over five cycles with good reversibility. This work indicates that DESs as green solvents have great potential for the totally green pretreatment of samples during the enrichment and purification processes.
authors.affiliation: College of Pharmaceutical Science, Hebei University & Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education, Baoding 071002, China.
authors.forename: Najing
authors.initials: N
authors.lastname: Fu
authors.affiliation: College of Pharmaceutical Science, Hebei University & Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education, Baoding 071002, China.
authors.forename: Runqiu
authors.initials: R
authors.lastname: Lv
authors.affiliation: College of Pharmaceutical Science, Hebei University & Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education, Baoding 071002, China.
authors.forename: Zhixin
authors.initials: Z
authors.lastname: Guo
authors.affiliation: College of Pharmaceutical Science, Hebei University & Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education, Baoding 071002, China.
authors.forename: Yiwei
authors.initials: Y
authors.lastname: Guo
authors.affiliation: College of Pharmaceutical Science, Hebei University & Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education, Baoding 071002, China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: You
authors.affiliation: College of Pharmaceutical Science, Hebei University & Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education, Baoding 071002, China. Electronic address: tangbaokun@hbu.edu.cn.
authors.forename: Baokun
authors.initials: B
authors.lastname: Tang
authors.affiliation: Department of Preventive Medicine and Health Management, Hebei University & Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education, Baoding 071002, China.
authors.forename: Dandan
authors.initials: D
authors.lastname: Han
authors.affiliation: Department of Preventive Medicine and Health Management, Hebei University & Key Laboratory of Medicinal Chemistry and Molecular Diagnosis, Ministry of Education, Baoding 071002, China. Electronic address: yanhy@hbu.edu.cn.
authors.forename: Hongyuan
authors.initials: H
authors.lastname: Yan
authors.affiliation: Department of Chemistry and Chemical Engineering, Inha University, Incheon 402751, South Korea. Electronic address: rowkho@inha.ac.kr.
authors.forename: Kyung Ho
authors.initials: KH
authors.lastname: Row
mesh_terms: D028023:Arecaceae / Q000737:chemistry* / Q000378:metabolism; D002794:Choline / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D013058:Mass Spectrometry; D008855:Microscopy, Electron, Scanning; D059808:Polyphenols / Q000032:analysis* / Q000302:isolation & purification; D052616:Solid Phase Extraction; D012997:Solvents / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013818:Thermogravimetry; D014508:Urea / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D059808:Polyphenols; D012997:Solvents; D014867:Water; D014508:Urea; D002794:Choline
keywords: Choline chloride; Deep eutectic solvents; Green; Polyphenol; Pretreatment