Search

The solubility of limonin in the binary solvent mixtures (methanol + water) and (acetone + water) with various initial mole fractions of methanol or acetone was measured by high-performance liquid chromatography (HPLC) at different temperatures ranging from 283.2 K to 318.2 K. The solubility of limonin increased with increasing initial mole fraction of methanol in (methanol + water) mixtures, whereas it had a maximum point at 0.9 mol fraction of acetone in (acetone + water) mixtures. The solubility of limonin increased with increasing temperature in the two binary solvent mixtures. The solubility of limonin was correlated with temperature by the van’t Hoff model and the modified Apelblat model, and the fitting results showed that the modified Apelblat model had better correlation. The CNIBS/Redlich–Kister model and the simplified CNIBS/Redlich–Kister model were used to correlate the solubility data with the initial solvent composition, the results show that the CNIBS/Redlich–Kister model reveals better agreement with the experimental values. Furthermore, to illustrate the effects of both temperature and initial solvent composition on the changes in the solubility of limonin, the solubility values were fitted by the Jouyban–Acree, van’t Hoff–Jouyban–Acree, modified Apelblat–Jouyban–Acree, Ma and Sun models. Among the five models, the Jouyban–Acree model give the best correlation results for (methanol + water) binary solvent mixtures, while the experimental solubility in the (acetone + water) system was most accurately correlated by the van’t Hoff–Jouyban–Acree model.

In this work, the superparamagnetic Fe 3 O 4 particles prepared by the coprecipitation method were coated successively by SiO 2 , vinyl end groups and molecularly imprinted polymer (MIP) shells to afford a pomegranate-like core/shell superparamagnetic particle (Fe 3 O 4 @SiO 2 @MIP), and the MIP shell preparation conditions were optimized by multi-objective response surface methodology. In order to simultaneously enrich and separate the four taxoids (10-DAB, baccatin III, cephalomannine and paclitaxel), cephalomannine was selected as the template because of its similar chemical structure to other three taxoids and relative inexpensiveness. Especially, to avoid template leaking which may influence the accuracy of identification and quantitation of the analytes, we selected paclitaxel as the target molecular during the investigation of the adsorption property of Fe 3 O 4 @SiO 2 @MIP particles. This strategy was similar to the dummy molecular imprinting technique in which the dummy molecularly imprinted polymer was prepared by using a dummy template, structural analog of the target analyte. The as-prepared Fe 3 O 4 @SiO 2 @MIP particles were characterized by transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), and Fourier transform infrared spectroscopy (FTIR). The adsorption kinetics, isotherms and reusability were also investigated. Finally, the Fe 3 O 4 @SiO 2 @MIP particles were successfully applied to simultaneously enrich and separate these four taxoids in the extract of Taxus × media ( T. × media ).

A novel molecularly imprinted polymer (MIP) using the specific ionic liquid (i.e. 1-vinyl-3-carboxymethylimidazolium bromide, 1-vinyl-3-carboxyethylimidazolium bromide, 1-viny-3-carboxybutylimidazolium bromide, or 1-vinyl-3-carboxypentylimidazolium bromide) as functional monomer was prepared via precipitation polymerization, which can be used to selectively separate synephrine (SYN) from methanol-water media. Ionic liquids are facile to be designed with varying the cation or anion, which enables the specific ionic liquid to be effectively designed to be a functional monomer for the preparation of MIP. The MIP showed a good selectivity and high adsorption capacity for SYN in methanol-water media. The adsorption process could be described by the pseudo-first-order model, which meant that the adsorption kinetics described a diffusion-controlled process. The equilibrium data fitted well to the Freundlich model, indicating multilayer adsorption. Finally, the MIP were successfully applied as sorbent to selectively enrich and separate SYN from the extracts of Aurantii Fructus Immaturus with a relatively high recovery (80-90%).

An improved high-performance liquid chromatography method for the separation and determination of rotungenic acid and two isomeric triterpene acids (oleanolic acid and ursolic acid) was developed. Results proved that these triterpene acids can be separated with high resolution by adding hydroxypropyl-β-cyclodextrin (HP-β-CD) into the mobile phase; the resolution of the triterpene acids increased and their retention time in the column decreased with HP-β-CD concentrations increasing due to the formation of inclusion complexes between triterpene acids and HP-β-CD. The formation of 1:1 inclusion complexes was assumed and apparent formation constants of triterpene acids with HP-β-CD were determined experimentally at 20°C and 35°C. At last, the method was used to determine rotungenic acid, oleanolic acid, and ursolic acid in the leaves of Diospyros kaki and proved to be sensitive, rapid, accurate, and suitable.

In this work, molecularly imprinted solid-phase extraction (MISPE) has been used to selectively enrich, purify, or remove synephrine from Aurantii Fructus Immaturus. To this end, a molecularly imprinted polymer (MIP) was prepared by self-assembly from the template synephrine, the functional monomer methacrylic acid, and the crosslinker ethylene glycol dimethacrylate in 1:4:20 molar ratio. Subsequent molecular interrogation of the MIP binding sites revealed preferential structural selectivity for synephrine relative to other structurally related naturally occurring compounds (i.e. octopamine and tyramine ). This selectivity was subsequently exploited to achieve substantial sample clean-up of extracts of crude Aurantii Fructus Immaturus and Aurantii Fructus Immaturus stir-baked with bran. The purity of synephrine in the extracts after MISPE represented approximately 24.21-fold enrichment of the synephrine in the untreated extracts of Aurantii Fructus Immaturus stir-baked with bran. High recoveries (85-90%) from the samples proved that the method was valid for selective enrichment, purification, or removal of synephrine from Aurantii Fructus Immaturus.

Ionic liquid (IL) based ultrasonic assisted extraction (ILUAE) was developed for the effective extraction of puerarin from Radix Puerariae Lobatae (RPL). The ILUAE parameters including the type of ILs, IL concentration, RPL amount, ultrasonic power and time were optimized by single-factor experiment and response surface methodology. Under the optimized experimental conditions, the best results were obtained using RPL amount 0.43 g in 10 mL 1.06 mol L −1 1-butyl-3-methylimidazolium bromide aqueous solution, ultrasonic time 27.43 min and ultrasonic power 480 W. Scanning electron microscope images of RPL samples were obtained to provide visual evidence of the sonication effect. Compared with the conventional ultrasonic assisted extraction and refluent extraction, the proposed ILUAE offered shorter extraction time and remarkable higher efficiencies due to the higher penetration ability and solubility of IL and the cavitation phenomenon produced in the solvent by the passage of an ultrasonic wave, which further supported the suitability of the proposed approach.

The feasibility and generic applicability of directly integrating conventional discrete operations of cell disruption by high pressure homogenizer and the product capture by aqueous two-phase extraction (ATPE) system have been demonstrated for the extraction of intracellular L-asparaginase from E. coli. In a side-by-side comparison with the conventional ATPE process, including cell disruption, centrifugal clarification and following ATPE, purification of L-asparaginase via this novel in situ ATPE process yielded a product of L-asparaginase with a higher specific activity of 94.8 U/(mg protein) and a higher yield of 73.3%, both of which in the conventional ATPE process were 78.6 U/(mg protein) and 52.1 %, respectively. In the purification of L-asparaginase (pI=4.9), product-debris interactions commonly diminish its recovery. It was demonstrated that immediate extraction of L-asparaginase in ATPE systems when it is released at pH 5.0 during cell disruption effectively increased its recovery in the top phase due to the reduced interaction between L-asparaginase and cell debris and the reduced degradation by contaminated protease. In addition, no clarification step and/or disruptate storage are required in this in situ ATPE, which reduced the number of unit operations and thus shortened the overall process time. This novel process has a good potential for the separation of other intracellular biological products.