Guizhen Li

Hybrid molecularly imprinted polymers modified by deep eutectic solvents and ionic liquids with three templates for the rapid simultaneous purification of rutin, scoparone, and quercetin from Herba Artemisiae Scopariae.

Different kinds of deep eutectic solvents based on choline chloride and ionic liquids based on 1-methylimidazole were used to modify hybrid molecularly imprinted polymers with the monomer γ-aminopropyltriethoxysilane-methacrylic and three templates (rutin, scoparone, and quercetin). The materials were adopted as solid-phase extraction packing agents, and were characterized by FTIR spectroscopy and field emission scanning electron microscopy. The hybrid molecularly imprinted polymers modified by deep eutectic solvents had high recoveries and a strong recognition of rutin, scoparone, and quercetin in Herba Artemisiae Scopariae than those modified by ionic liquids. In the procedure of solid-phase extraction, deep eutectic solvents-2-hybrid molecularly imprinted polymers were obtained with the best recoveries with rutin (92.27%), scoparone (87.51%), and quercetin (80.02%), and the actual extraction yields of rutin (5.6 mg/g), scoparone (2.3 mg/g), and quercetin (3.4 mg/g). Overall, the proposed approach with the high affinity of hybrid molecularly imprinted polymers might offer a novel method for the purification of complex samples.

Magnetic Graphene Oxide modified by Imidazole-based Ionic Liquids for the Magnetic-based Solid-phase Extraction of Polysaccharides from Brown alga

Magnetic graphene oxide was modified by four imidazole-based ionic liquids to synthesize materials for the extraction of polysaccharides by magnetic solid-phase extraction. Fucoidan and laminarin were chosen as the representative polysaccharides owing to their excellent pharmaceutical value and availability. Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, and thermogravimetric analysis were applied to characterize the synthesized materials. Single-factor experiments showed that the extraction efficiency of polysaccharides was affected by the amount of ionic liquids for modification, solid-liquid ratio of brown alga and ethanol, the stirring time of brown alga and ionic liquid-modified magnetic graphene oxide materials, and amount of 1-(3-aminopropyl)imidazole chloride modified magnetic graphene oxide materials added to the brown alga sample solution. The results indicated that 1-(3-aminopropyl)imidazole chloride modified magnetic graphene oxide possessed better extraction ability than graphene oxide, magnetic graphene oxide, and other three ionic-liquid-modified magnetic graphene oxide materials. The highest extraction recoveries of fucoidan and laminarin extracted by 1-(3-aminopropyl)imidazole chloride modified magnetic graphene oxide were 93.3 and 87.2%, respectively. In addition, solid materials could be separated and reused easily owing to their magnetic properties.

Deep eutectic solvents for the purification of chloromycetin and thiamphenicol from milk

Deep eutectic solvents were used in both dispersive liquid-liquid microextraction and solid-phase extraction for the purification of chloromycetin and thiamphenicol from milk. In the dispersive liquid-liquid microextraction procedure, deep eutectic solvents mixed with chloroform at different ratios (0:1-5:1, v/v) were used as the extraction agent to optimize the procedure, and the ratio of 2:1 v/v was found to be the best extraction agent with 87.23 and 83.17% recoveries of chloromycetin and thiamphenicol, respectively. Furthermore, deep eutectic solvents were also used to modify molecular imprinted polymers in solid-phase extraction procedure, and the polymers were used to purify chloromycetin and thiamphenicol from milk. Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy were used to characterize the polymers. The solid-phase extraction recoveries with deep eutectic solvents with molecularly imprinted polymers (chloromycetin and thiamphenicol, two templates), molecularly imprinted polymers (without deep eutectic solvents), and nonimprinted polymers (without a template) for chloromycetin were 91.23, 82.64, and 57.3%, respectively, and recoveries for thiamphenicol were 87.02, 79.03, and 52.27%, respectively. The recoveries of chloromycetin and thiamphenicol from milk in the solid-phase extraction procedure were higher than using deep eutectic solvents mixed with chloroform as the extraction agent in the dispersive liquid-liquid microextraction procedure.

Optimal separation of phenol from model oils by forming deep eutectic solvents with quaternary ammonium salts

Various quaternary ammonium salts are used to separate phenol from model oil by forming deep eutectic solvents (DESs). The results indicate that the types of quaternary ammonium salt ions and the molecular symmetry of quaternary ammonium have obvious influence on recovery for phenol. Tetraethylammonium chloride (TEAC), which contains suitable ions and symmetry reveals highest phenol recovery in the model oil. The separation mechanism is discussed and the structures of DESs (TEAC/Phenol) are proved on Fourier transform infrared transform (FTIR). To recycle TEAC, diethyl ether is used as anti-solvent to precipitate TEAC from TEAC/Phenol system. The structure of regeneration TEAC is proved on FTIR and 1H NMR. The recovery for phenol is decreased from 97.45% to 14.30% with the increase of regeneration times. The optimal separation condition was obtained by response surface methodology at 30 °C (separation temperature) for 40 min (separation time) with 3.75 g TEAC (mass of TEAC) in 10 mL model oil (phenol recovery: 99.3%). In contrast to the traditional methods to separate phenol, this proposed method avoids the use of alkalis and acid, and with less effluent.

Recent Applications of Molecularly Imprinted Polymers (MIPs) on Micro-extraction Techniques

Microextraction is considered as one of the most critical steps in the entire analytical process because it can effectively remove interference and pre-concentrate the target analytes. Molecularly imprinted polymers (MIPs) are synthetic polymers with a predetermined selectivity for a given analyte, or group of structurally related compounds, which are excellent materials for sample preparation in the process of microextraction owing to their high selectivity and ability. This review provides a critical overview of the synthesis and characterization of MIPs, with a focus on recent applications in the field of solid-phase microextraction (SPME) and liquid-phase microextraction (LPME). The advantages and drawbacks of the applications of MIPs used in SPME and LPME as well as the future expected trends are also discussed.

Applications of Magnetic Molecularly Imprinted Polymers (MMIPs) in the Separation and Purification Fields

Magnetic molecularly imprinted polymers (MMIPs) have attracted considerable attention in recent years as multifunctional materials suitable for use in the separation and purification fields. When modified with a specific functional polymer, MMIPs can be used to extract chemicals from a matrix and concentrate them based on specific recognition features, enabling more convenient retrieval of analytes using an external magnetic field. This review covers the preparation, characterization, and applications of various MMIPs, with particular focus on the technique used to coat such MMIPs with functional groups. A comprehensive overview of the applications of MMIPs to electrochemistry, food, and environmental analysis, and medicine is also presented. Furthermore, the problems and trends associated with MMIP-based applications are discussed.Graphical Abstract

Selective extraction of 3,4-dihydroxybenzoic acid in Ilex chinensis Sims by meticulous mini-solid-phase microextraction using ternary deep eutectic solvent-based molecularly imprinted polymers

AbstractA ternary deep eutectic solvent (TDES) was used as both template and functional monomer in the synthesis of TDES-based molecularly imprinted polymers (TDES-MIPs). A meticulous miniaturized solid-phase microextraction (mini-SPME) method followed by high-performance liquid chromatography (HPLC) were used for the optimal speciation of 3,4-dihydroxybenzoic acid (3,4-DHBA) in the needle of a syringe system with response surface methodology (RSM). Under the optimal conditions for the determination of 3,4-DHBA (amount of adsorbent (2xa0mg), sample volume (1xa0mL), cycles for adsorption and desorption (6)), the actual extraction amount was 8.46xa0μgxa0g−1. The limits of detection (LODs, S/Nu2009=u20093) for 3,4-DHBA in Ilex chinensis Sims were 0.26–0.31xa0μgxa0mL−1, and the intra-day and inter-day precision (relative standard deviations, nu2009=u20094) after spiking with 5xa0μgxa0mL−1, 100xa0μgxa0mL−1, and 200xa0μgxa0mL−1 were both less than 4.21%. The meticulous method (TDES-MIP-mini-SPME) combined with RSM offers a significant advance over existing methods, because of the meticulous operation and excellent selectivity of 3,4-DHBA from complex samples.n Graphical abstractᅟ

Molecularly Imprinted Polymers Modified by Deep Eutectic Solvents and Ionic Liquids with Two Templates for the Simultaneous Solid-Phase Extraction of Fucoidan and Laminarin from Marine Kelp

Abstract Molecularly imprinted polymers modified by deep eutectic solvents and ionic liquids (ILs) were prepared as packing materials for the solid-phase extraction (SPE) of fucoidan and laminarin. The prepared materials were characterized by field emission scanning electron microscopy and Fourier transform infrared spectroscopy. The polymers modified by the deep eutectic solvent prepared by choline chloride and urea had the best extraction efficiencies for fucoidan and laminarin (95.5% and 87.6%, respectively) from marine kelp. The relative standard deviations for intraday and interday determination were less than 4.23%. The molecularly imprinted polymers modified by deep eutectic solvents and ILs showed outstanding applications for SPE and may offer novel sample pretreatment for other analytes.

Magnetic hybrid imprinted polymers with three-templates modified by DESs for the rapid purification of monosaccharide from seaweed

ABSTRACT Fe3O4@hybrid-molecular-imprinted polymers (Fe3O4@HMIPs) with three monosaccharide templates (D-(+)-galactose, L-(−)-fucose, and D-(+)-mannose), and hybrid materials were modified by deep eutectic solvents (DESs). The materials obtained were combined with solid-phase extraction (SPE) to purify of D-(+)-galactose, L-(−)-fucose, and D-(+)-mannose from seaweed, and the SPE procedure was optimized further. Compared to Fe3O4@HMIPs, DESs-Fe3O4@HMIPs were developed to achieve stronger recognition and higher recoveries of D-(+)-galactose, L-(−)-fucose, and D-(+)-mannose from seaweed. The optimal practical recoveries of the three monosaccharides, D-(+)-galactose, L-(−)-fucose, and D-(+)-mannose, purified by DESs-4-Fe3O4@HMIPs from seaweed were 90.12, 92.82, and 91.94%, respectively. When acetone was used as the washing solution, the actual amounts extracted were 6.87, 4.17, and 5.29u2009mgu2009·u2009g−1, respectively. GRAPHICAL ABSTRACT

Extraction and Determination of Quercetin from Ginkgo biloba by DESs-Based Polymer Monolithic Cartridge

Deep eutectic solvents (DES) were formed from choline chloride (ChCl). DES-modified polymer monolithic (DES-M), template molecular polymer monolithic and non-DES-M without a molecular template were synthesized in identical process. These polymer materials were characterized by field emission scanning electron microscopy and Fourier transform infrared spectroscopy. The significant selective adsorption properties of the polymers were assessed by an absorption capacity experiment and solid-phase extraction (SPE). The optimized extraction procedure was as follows: ultrasonic time (30 min), optimal solvent (ethanol) and liquid to material ratio (20 mL g-1). Under this condition, the amount of quercetin extracted from Ginkgo biloba was 290.8 mg g-1. The purification of G. biloba was achieved by the SPE process. Based on the results, DESs-based monolithic cartridges can be used for simple and efficient extraction and as a pre-concentration technique for the purification of bioactive compounds or drugs in aqueous environments with high affinity and selectivity.