Enantioseparation of racemic amlodipine using immobilized ionic liquid by solid-phase extraction.

In this paper, a novel l-glutamate based immobilized chiral ionic liquid (SBA-IL (Glu)) was prepared by chemical bonding method and applied as a solid sorbent for chiral separation of amlodipine. The performance of SBA-IL (Glu) was investigated for the absorption of (S)-amlodipine and separation of amlodipine enantiomer. The static experiment showed that equilibrium adsorption was achieved within 80 minutes, and the saturation adsorptions capacity was 12 mg/g. The complex was then packed in a glass chromatographic column for the separation of amlodipine and the enantiomeric excess (%ee) of (S)-amlodipine reached 24.67%. The immobilized ionic liquids exhibit good reusability, and the separation efficiency remains 18.24% after reused five times, which allows potential scale-up for the chiral separation of amlodipine.

Enantioseparation of flurbiprofen enantiomers using chiral ionic liquids by liquid-liquid extraction.

Flurbiprofen is a kind of nonsteroidal anti-inflammatory drug, which has been widely used in clinic for treatment of rheumatoid arthritis and osteoarthritis. It has been reported that S-flurbiprofen shows good performance on clinic anti-inflammatory treatment, while R-enantiomer almost has no pharmacological activities. It has important practical values to obtain optically pure S-flurbiprofen. In this work, chiral ionic liquids, which have good structural designability and chiral recognize ability, were selected as the extraction selector by the assistance of quantum chemistry calculations. The distribution behaviors of flurbiprofen enantiomers were investigated in the extraction system, which was composed of organic solvent and aqueous phase containing chiral ionic liquid. The results show that maximum enantioselectivity up to 1.20 was attained at pH 2.0, 25°C using 1,2-dichloroethane as organic solvent, 1-butyl-3-methylimidazole L-tryptophan ([Bmim][L-trp]) as chiral selector. The racemic flurbiprofen initial concentration was 0.2 mmol L-1 , and [Bmim][L-trp] concentration was 0.02 mol L-1 . Furthermore, the recycle of chiral ionic liquids has been achieved by reverse extraction process of the aqueous phase with chiral selector, which is significant for industrial application of chiral ionic liquids and scale-up of the extraction process.

Continuous Synthesis of Uniformly Dispersed Mesoporous SBA-15 Supported Silver Nanoparticles in a Coiled Flow Inverter Reactor.

Mesoporous silica supported nanocatalysts have shown great potential in industrial processes due to their unique properties, such as high surface area, large pore volume, good chemomechanical stability and so on. Controllable and tunable synthesis of supported nanocatalysts is a crucial problem. Continuous synthesis of supported nanoparticles has been reported to get uniformly dispersed nanomaterials. Here, a method for continuous synthesis of uniformly dispersed mesoporous SBA-15 supported silver nanoparticles in a coiled flow inverter (CFI) microreactor is described. Compared to Ag/SBA-15 synthesized in the conventional batch reactor and Ag synthesized in continuous flow, mesoporous silica nanocatalysts synthesized in continuous flow are found to have smaller average size (7-11 nm) and narrower size distribution. The addition of capping agents can effectively change the characteristic of catalysts. Moreover, two kinds of support with different surface area and pore size have been added into the continuous synthesis. This method can provide further understandings for the synthesis of uniformly dispersed supported nanocatalysts in continuous flow, especially for mesoporous nanomaterials, which provides the possibilities of large-scale yield process of supported nanocatalysts in industry.

Exploiting equilibrium-kinetic synergetic effect for separation of ethylene and ethane in a microporous metal-organic framework.

Physisorption is a promising technology to cut cost for separating ethylene (C2H4) from ethane (C2H6), the most energy-intensive separation process in the petrochemical industry. However, traditional thermodynamically selective adsorbents exhibit limited C2H4/C2H6 selectivity due to their similar physiochemical properties, and the performance enhancement is typically at the expense of elevated adsorption heat. Here, we report highly-efficient C2H4/C2H6 adsorption separation in a phosphate-anion pillared metal-organic framework ZnAtzPO4 exploiting the equilibrium-kinetic synergetic effect. The periodically expanded and contracted aperture decorated with electronegative groups within ZnAtzPO4 enables effective trapping of C2H4 and impedes the diffusion of C2H6, offering an extraordinary equilibrium-kinetic combined selectivity of 32.4. The adsorption heat of C2H4 on ZnAtzPO4 (17.3 to 30.0 kJ mol-1) is substantially lower than many thermodynamically selective adsorbents because its separation capability only partially relies on thermodynamics. The separation mechanism was explored by computational simulations, and breakthrough experiments confirmed the excellent C2H4/C2H6 separation performance of ZnAtzPO4.

Sample capacity in preparative high-speed counter-current chromatography.

High-speed counter-current chromatography (HSCCC) is a versatile technique in preparative separation and purification of pure compounds from complex matrices. As a preparative chromatography, there is a need to maximize the column production. Based on the plate theory of Van Deemter, the effect of the sample load on the separation was investigated in a preparative HSCCC with a 1000 ml column capacity. The test samples of hydroquinone, pyrocatechol and phenol were separated using a two-phase solvent system of n-hexane-ethyl acetate-ethanol-water (1:1:1:1, v/v/v/v) at different sample loads. The results showed that for the case of HSCCC, the agreement of the effect of sample load on peak height and peak width between the Van Deemter's theory and the experiments is excellent. Furthermore, the factors limiting the mass load, including the resolution between the peaks, the partition isotherm and the solute solubility were also discussed.

Simultaneous quantification of three major bioactive triterpene acids in the leaves of Diospyros kaki by high-performance liquid chromatography method.

The leaf of Diospyros kaki, which is a traditional Chinese medicine, has been used for the treatment of various diseases. In order to improve the quality assurance of the leaves of D. kaki, derived extracts and phytomedicines, a simple, rapid and accurate high-performance liquid chromatography (HPLC) method was developed to simultaneously assess the three bioactive triterpene acids: barbinervic acid (BA) and its epimer, rotungenic acid (RA), along with 24-hydroxy ursolic acid (HA). This HPLC assay was performed on a reversed-phase C18 column with methanol and aqueous H3PO4 as the mobile phase and using a monitoring wavelength at 210 nm. This method was successfully applied to quantify these three bioactive triterpene acids in five different solvent extracts of the leaves of D. kaki and in the leaves from six different locations in China. The results demonstrated the total content and quantity of each of the main bioactive compounds were strongly dependent on the extraction solvents and locations, indicating that the quality control of the bioactive ingredients in the leaves of D. kaki, derived extracts and phytomedicines is critical to ensure its clinical benefits. The content of the total triterpenoids was also determined by the less selective colorimetric method, and the comparison with the HPLC method was given.

Axial dispersion coefficient in high-speed counter-current chromatography.

Experimental measurements of axial dispersion coefficients in high-speed counter-current chromatography have been carried out in the single-phase and two-phase modes. Axial dispersion coefficients were calculated from the residence time distribution curve (or the elution profile). The experimental data obtained were used to develop a model involving Peclet number Pe, Reynolds number and the ratio of flow velocity u to linear angular velocity u(theta) for predicting the axial dispersion coefficient. Furthermore, the models obtained from the single-phase and two-phase modes were compared, and a counterintuitive phenomenon was found in that the effects of the flow rate and the rotation speed on the axial dispersion coefficients are inconsistent: the axial dispersion coefficient decreases with the rotation speed and increases with the flow rate in the single-phase mode, but increases with rotation speed and decreases slightly with the flow rate in the two-phase mode.

Simultaneous determination of four sesquiterpene alkaloids in Tripterygium wilfordii Hook. F. extracts by high-performance liquid chromatography.

Wilfortrine, wilfordine, wilforgine and wilforine are four major bioactive sesquiterpene alkaloids in Tripterygium wilfordii Hook. F. The first analytical determination of the four major bioactive alkaloids is described. The four alkaloids are well-resolved within 15 min using the developed HPLC method. The identity of the analytes was confirmed by an HPLC-MS experiment, with all compounds being clearly assignable by atmospheric pressure chemical ionization (APCI) positive mode analysis. The method was validated for limit of qualification, linearity and inter-day variation of precision and accuracy. Seven T. wilfordii samples (extracts and commercial product) were successfully analysed.