Further study of the viscoelastic phase separation of cyanate ester modified with poly(ether imide)

In this study, the viscoelastic phase separation process was studied further by time‐resolved light scattering, differential scanning calorimetry, and scanning electron microscopy in the system of poly(ether imide)‐modified bisphenol‐A dicyanate. It was observed that the evolution time of phase structure and relaxation time of diffusion flow of the bisphenol‐A dicyanate were similar with the phase diagram of curing conversion versus content of PEI. The results suggested that the viscoelastic phase separation was affected by the curing conversion of the system at the onset point of phase separation. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 517–523, 2006     

高速逆流色谱法分离茶叶中的生物碱

以氯仿－甲醇－磷酸二氢钠缓冲液（２３ｍｍｏｌ／Ｌ,ｐＨ５．６）（体积比４∶３∶２）为溶剂系统,上相为固定相,下相为移动相,从茶叶的总生物碱中分离出三个成分,其中一个是咖啡碱,一个是茶碱,另一个待定。将分离结果与ＴＬＣ分离结果相比较,证实了高速逆流色谱法的有效及实用性。     

高速逆流色谱法分离纯化续随子种子中的七叶内酯

建立了高速逆流色谱(HSCCC)技术分离纯化续随子种子中七叶内酯的方法。将续随子种子的乙酸乙酯萃取物直接进行高速逆流色谱分离,考察了不同溶剂系统的分离效果。结果表明,最佳的溶剂系统为氯仿-甲醇-水(体积比为4:3:2),以其上相为固定相,下相为流动相。从200 mg续随子种子乙酸乙酯萃取物中分离得到80 mg七叶内酯,纯度为99.04%。HSCCC技术可高效分离纯化续随子种子中的七叶内酯,为得到高纯度的七叶内酯提供了制备技术。     

FOUR COMPONENT PHASE EQUILIBRIA WITH TETRAMETHYLDIOCTYLDISILOXANE

A complete phase diagram was determined for the system: water, butanol, propanol, and tetramethyldioctyldisiloxane (TDDS) using refractive index and gas chromatography. The solubility limits were established by quantitative analysis and compared to the refractive index of known single-phase mixtures. The system contained three two-phase regions and one three-phase region, which separated from one large continuous single phase. The system exhibited a preferential phase stability, which inversely changed with the increase in polarity of the solution. Once a ratio of 3-1 water-propanol was obtained, the phase separation shifted from TDDS to water. The content of the amphophilic components influenced the solubility of TDDS and is reflected in the phase equilibria.     

HPLC technique for quantitation of Chimassorb 944, and its evaluation in analysis of real and standard samples of polyolefins

A high performance liquid chromatography (HPLC) method is presented for the determination of Chimassorb 944 in polymeric matrix. A reversed phase column octadecyl silane (ODS) is used as a stationary phase. As a mobile phase, a mixture of THF:methanol:triethanol amine (90:10:1.5) (v:v:w) is used. The HPLC system was equipped with an UV detector and the absorbance of the analyte was recorded at 240 nm. In the case of polymers, 0.5 g of them along with 100 mg Irganox 1010 (for preventing oxidation of Chimassorb 944) were dissolved in boiling xylene, and then extracted with sulfuric acid 1 M four times. The extract was neutralized with sodium hydroxide solution and the analyte was re-extracted into carbon tetrachloride and then injected to the HPLC system. This method is an accurate and relatively fast technique for determination of Chimassorb 944 in polymers.     

Preparative separation of cichoric acid from Echinacea purpurea by pH-zone-refining counter-current chromatography

pH-zone-refining counter-current chromatography was successfully applied to the separation of cichoric acid from Echinacea Purpurea (L.) Moench. A 3.0 g quantity of sample was separated using the following two-phase solvent system: MtBE-CH3CN-water (4:1:5, v/v), 10 mM trifluoroacetic acid in organic stationary phase and 10 mM ammonia in aqueous mobile phase. The obtained fractions were analyzed by high-performance liquid chromatography and negative ion electrospray ionization mass spectrometry. Double separations were performed with the same solvent system yielding 563 mg cichoric acid at 95.6% purity.     

Efficient protocol for purification of diosgenin and two fatty acids from Rhizoma dioscoreae by SFE coupled with high-speed counter-current chromatography and evaporative light scattering detection

Supercritical fluid extraction (SFE) was used to extract diosgenin, linoleic acid, and linolenic acid following acid hydrolysis from Rhizoma dioscoreae, a famous traditional Chinese medicine. The process was performed using a preparative SFE system under 35 MPa of pressure, 65 degrees C of temperature, and modified CO(2) with 95% ethanol for 180 min dynamic extraction. Then, the crude extract was successfully isolated and separated by high-speed counter-current chromatography (HSCCC) with evaporative light scattering detection (ELSD). A two-phase solvent system composed of n-hexane/ethyl acetate/methanol/water was used for HSCCC separation in a stepwise elution mode. The upper phase of the solvent system at the volume ratio of 1:1:1.4:0.6 by volume was used as the stationary phase, and the mobile phase after 200 min was changed into the lower phase of the solvent system at the volume ratio of 1:1.2:1.4:0.6 by volume. The separation produced a total of 20.8 mg diosgenin, 12.1 mg linoleic acid, and 18.4 mg linolenic acid from 300 mg crude extract in one-step purification. The purities of the products were 98.9, 99.0, and 99.4%, respectively, as determined by HPLC. Their chemical structures were identified by MS, UV, and the standards.     

Reverse phase thin-layer chromatographic separation of bromodiphenhydramine and diphenhydramine.

A thin-layer chromatographic system is described for the separation of diphenhydramine and bromodiphenhydramine which is based on a reverse phase paper chromatographic system developed by J. Vecerková (2,3) in 1962. Chromatographic systems for this separation described in the literature and several systems attempted in this laboratory using normal chromatography have not proven successful. The method using reverse phase thin-layer chromatography involves a stationary phase of mineral oil on silica gel G and a mobile phase of ethanol:water:ammonium hydroxide, 28% NH3, (55:43:2). A 10-cm length of run requires about three hours and provides an excellent separation of the two compounds for identification-differentiation purposes.     

Binary versus ternary interactions in a completely miscible three‐polymer blend system: Poly(ϵ‐caprolactone) with two different methacrylic polymers

A truly miscible ternary miscible blend consisting of poly(?‐caprolactone) (PCL), poly(phenyl methacrylate), and poly(benzyl methacrylate) (PBzMA) was discovered. The three‐polymer blend system was completely miscible within the entire composition range at ambient temperature up to about 150 °C, and ternary phase diagrams at increasing temperatures were characterized and interpreted. A ternary‐interaction model based on the modified Flory–Huggins expression was used to describe the phase diagrams with the individual binary interaction strengths. The model fitted well with the experimental‐phase diagram for the ternary blend system at T = 250 °C, where the binary PCL‐PBzMA blend system is on the critical points of phase separation. Interpretation of discrepancy between the model and experimental at other temperatures was handled with an empirical approach. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 747–754, 2002     

低速逆流色谱分离制备栀子黄色素中的藏花素

建立了低速逆流色谱技术(SRCCC)从栀子黄色素中快速分离制备藏花素的方法。两相溶剂系统由叔丁基甲基醚-正丁醇-乙腈-水(2:2.5:1:5, v/v/v/v)组成,以上相为固定相,下相为流动相。在转速为50 r/min和流速为5 mL/min的条件下,从5 g栀子黄色素粗样中分离得到2.47 g藏花素,纯度为96.8%。该方法制备量大、安全、高效,有可能成为工业级分离制备藏花素的一种有效手段。     

Preparative isolation and purification of coumarins from Peucedanum praeruptorum Dunn by high-speed counter-current chromatography

A preparative high-speed counter-current chromatography (HSCCC) method for isolation and purification of coumarins from Peucedanum praeruptorum Dunn (Baihuaqianhu in Chinese) was successfully established by using light petroleum-ethyl acetate-methanol-water as the two-phase solvent system in gradient elution mode. The upper phase of light petroleum-ethyl acetate-methanol-water (5:5:5:5, v/v) was used as the stationary phase of HSCCC. The mobile phase used in HSCCC was the lower phase of light petroleum-ethyl acetate-methanol-water (5:5:5:5, v/v) and light petroleum-ethyl acetate-methanol-water (5:5:6.5:3.5, v/v) that was changed in gradient. Four kinds of coumarins and another unknown compound were obtained and yielded 5.3 mg of qianhucoumarin D, 7.7 mg of Pd-Ib, 35.8 mg of (+)-praeruptorin A, 31.9 mg of (+)-praeruptorin B and 6.4 mg of unknown compound with the purity of 98.6%, 92.8%, 99.5%, 99.4% and 99.8% in one-step separation, respectively. The structures of the coumarins were identified by 1H NMR and 13C NMR.     

Chemically induced phase separation in the preparation of porous epoxy monolith

A methodology for preparing porous epoxy monolith via chemically induced phase separation was proposed. The starting system was a mixture of an epoxy precursor, diglycidyl ether of bisphenol‐A (DGEBA), a curing agent, 4,4′‐diaminodiphenylmethane (DDM), and a thermoplastic polymer, polypropylene carbonate (PPC). As DGEBA was cured with DDM, the system became phase‐separated having PPC particles dispersed in epoxy matrix. After PPC particles were removed by thermal degradation, a porous structure was obtained. The phase separation mechanism was determined by the initial composition and illustrated by a pseudophase diagram. The pore size increased with increasing the concentration of PPC and raising the curing temperature. The intermediate and final morphologies of the system were studied using optical and scanning electron microscopy, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010     

Application of preparative high-speed counter-current chromatography for separation of chlorogenic acid from Flos Lonicerae

Chlorogenic acid, an ester formed between caffeic acid and quinic acid, is a major phenolic compound in the traditional Chinese medicinal herb Flos Lonicerae. The separation and purification of chlorogenic acid from the crude extract of Flos Lonicerae was achieved by high-speed counter-current chromatography (HSCCC). A high acid, highly polar two-phase solvent system containing n-butanol-acetic acid-water (4:1:5) was run on a preparative scale. The upper phase was used as the mobile phase in the head to tail elution mode. A 300-mg quantity of the crude extract containing 5.97% chlorogenic acid was loaded on a 342-ml HSCCC column. Double separations were performed with the same solvent system yielding 16.9 mg chlorogenic acid at 94.8% purity with approximately 90% recovery.     

Three‐phase solvent systems for the comprehensive separation of a wide variety of compounds from Dicranostigma leptopodum by high‐speed counter‐current chromatography

A three‐phase solvent system was efficiently applied for high‐speed counter‐current chromatography to separate secondary metabolites with a wide range of hydrophobicity in Dicranostigma leptopodum. The three‐phase solvent system of n‐hexane/methyl tert‐butyl ether/acetonitrile/0.5% triethylamine (2:2:3:2, v/v/v/v) was selected for high‐speed counter‐current chromatography separation. The separation was initiated by filling the column with a mixture of intermediate phase and lower phase as a stationary phase followed by elution with upper phase to separate the hydrophobic compounds. Then the mobile phase was switched to the intermediate phase to elute the moderately hydrophobic compounds, and finally the polar compounds still retained in the column were fractionated by eluting the column with the lower phase. In this research, 12 peaks were eluted out in one‐step operation within 110 min, among them, eight compounds with acceptable purity were obtained and identified. The purities of β‐sitosterol, protopine, allocryptopine, isocorydione, isocorydine, coptisine, berberrubine, and berberine were 94.7, 96.5, 97.9, 86.6, 98.9, 97.6, 95.7, and 92.8%, respectively.     

Analysis of protein gels formed by interfacial partitioning

 A special combination of alcoholic precipitation and salting out of proteins was described as three-phase partitioning (TPP). Proteins are accumulated in a coherent middle phase in the partitioning system composed of tert-butanol, ammonium sulphate and water. Partitioning systems with various ratios of components were investigated. The composition and the mechanical properties of the middle phase were determined in model systems using bovine serum albumin or ovalbumin. Quantitative analysis revealed that beside the protein content (2–10wt%) other components of the middle phase formed two immiscible liquid phases. The stress–deformation relationship obtained by uniaxial compression showed the elastic behaviour of the middle phase. The results suggested that the middle phase formed in TPP is an emulsion gel. A possible mechanism of the formation of an emulsion gel was outlined. Received: 3 August 2000 Revised: 23 November 2000 Accepted: 29 November 2000     

Enrichment and separation of antitumor triterpene acids from the epidermis of Poria cocos by pH‐zone‐refining counter‐current chromatography and conventional high‐speed counter‐current chromatography

Triterpene acids were extracted from the epidermis of Poria cocos (Schw.) Wolf. These acids were found to inhibit the growth of lung cancer cells in vitro and in vivo. An efficient method for the preparative separation of antitumor triterpene acids was established that involves the combination of pH‐zone‐refining counter‐current chromatography and conventional high‐speed counter‐current chromatography. We used pH‐zone‐refining counter‐current chromatography to concentrate the triterpene acids using a two‐phase solvent system composed of petroleum ether/ethyl acetate/methanol/water (3:7:5:5, v/v/v/v), trifluoroacetic acid (10 mM) was added to the upper phase as a retainer, and ammonia (10 mM) was added to the lower phase as an eluter. As a result, 200 mg concentrate of triterpene acids was obtained from 1.0 g of crude extract. The concentrate was further separated by conventional high‐speed counter‐current chromatography using a solvent system composed of petroleum ether/ethyl acetate/methanol/water (0.8:1.2:1.2:0.9, v/v), yielding 50 mg of poricoic acid A and 5 mg of poricoic acid B from 120 mg concentrate, respectively. The inhibitory activity of the major compound on lung A549 cells was examined and poricoic acid A was found to significantly inhibit the growth of A 549 cells.     

正交轴逆流色谱法分离标准蛋白质及实际样品

 以m(质量分数为 12 .5 %的PEG80 0 0 )∶m(质量分数为 2 5 %的磷酸氢二钾 ) =1∶1或m(质量分数为 12 .5 %的PEG80 0 0 )∶m(质量分数为 30 %的磷酸氢二钾 ) =1∶1为溶剂系统 ,用下相作流动相 ,上相作固定相 ,操作时采用5 0 0r/min的转速和 6 0mL/h的流动相流速 ,考察了正交轴逆流色谱法对标准蛋白质及羊肚菌糖蛋白和枸杞糖肽的分离情况。将结果与高效液相色谱分离结果相比较 ,前者在分离度损失不大的基础上提高了进样量 ,证明了其用于制备的有效性 ,从而为分离制备天然生物大分子提供了一个新方法。     

Phase Equilibria in Systems of Water,Naphthenic Acids,and Phenols

A partial phase diagram has been determined for the system based on 5‐phenylvalerate, 4‐pentyphenol, and water at 25 °C. The system showed a very rich phase behavior in which many different isotropic solutions and liquid crystals were found. Both normal and reverse self‐assembly structures of the micellar and hexagonal types were noted. In the middle of the phase diagram, a lamellar liquid crystalline phase with a large swelling capacity was observed. When the aromatic alcohol was replaced by a long‐chain alcohol the reverse hexagonal structure disappeared. The effect of temperature and salinity on the phase behavior was also studied. Raising the temperature increased the micellar regions, while the lamellar phase was slightly reduced and the reverse hexagonal phase disappeared. Addition of salt gave the lamellar phase a smaller region of existence and the large extension towards the water apex disappeared. Introduction of an acid to the system resulted in a remarkable change of the phase behavior: both the normal micellar and lamellar regions were significantly reduced, while the reverse micellar region was significantly increased.     

Separation of five oligostilbenes from Vitis amurensis by flow‐rate gradient high‐performance counter‐current chromatography

A rapid and efficient high‐performance counter‐current chromatography (HPCCC) method was developed to separate five oligostilbenes from the roots of Vitis amurensis. An n‐hexane/ethyl acetate/methanol/water system (4:8:4:10, v/v/v/v) was selected as an optimal two‐phase solvent system of which the upper phase was used as the stationary phase and the lower phase was used as the mobile one. Partition coefficient values for the target compounds under these optimized conditions were 0.28 ( 1 , ampleosin A), 7.12 ( 2 , (+)‐g‐viniferin), 2.26 ( 3 , vitisin A), 5.38 ( 4 , wilsonol C), and 11.23 ( 5 , vitisin B). Flow‐rate gradient HPCCC (4 mL/min in 0–70 min, 8 mL/min in 70–250 min) was applied to isolate the target compounds in as high purity as possible within the shortest possible run time. Under these conditions, ampelopsin A (12.1 mg), (+)‐g‐viniferin (10.4 mg), vitisin A (2.8 mg), wilsonol C (3.2 mg), and vitisin B (37 mg) were isolated with >95% purity from 150 mg of enriched oligostilbene extract. Although the K_D of the last eluted compound, vitisin B (K_D = 11.23), was relatively large, it was eluted in 115–145 min using the two‐phase solvent system. This study shows that HPCCC is an efficient tool for the isolation and purification of natural products.     

The intercalated smectic A phase. The liquid crystal properties of the α-(4-cyanobiphenyl-4'-yloxy)-ω)-(4-alkyloxycinnamoate)alkanes

A novel system of non-symmetric dimers containing 4-n-alkyloxy-substituted cinnamic acid and cyanobiphenyl groups has been studied. Two series were prepared: in one the flexible spacer was varied in length while the spacer was fixed. The spacer length has a profound influence on the nematic-isotropic transition temperature of these materials and a large odd-even effect is observed for the series. The terminal chain also plays a significant role in determining the liquid crystal phase behaviour: a smectic A phase is exhibited for the ethyl and propyl homologues, in addition to a nematic phase; this smectic phase vanishes for intermediate chain lengths but then reappears for the nonyl and decyl members of the series. X-ray diffraction has revealed the structure of the smectic A phase for the ethyl homologue to be intercalated, whereas that for the decyl compound is interdigitated. The existence of the intercalated smectic A phase has previously been explained in terms of a charge-transfer interaction between unlike mesogenic groups. However, for the non-symmetric liquid crystal dimers described here this specific interaction appears unlikely and we discuss, therefore, other possible mechanisms for the formation of intercalated smectic phases.