Enantiomeric separation of citalopram analogues by HPLC using macrocyclic glycopeptide and cyclodextrin based chiral stationary phases

The enantiomeric separation of a novel series of twenty-eight racemic mixtures of citalopram analogues was performed by high performance liquid chromatography (HPLC). Due to the effectiveness of citalopram as an antidepressant drug, the development of new compounds based on its chemical structure is interesting, and their enantiomeric separation is needed to allow further pharmacokinetic studies. Several bonded cyclodextrin (both native and derivatized) and macrocyclic glycopeptide based chiral stationary phases (CSPs) were evaluated for their ability to separate this set of compounds via HPLC. Polar ionic, polar organic, and reversed phase modes were tested. Twenty-five of the racemic mixtures were separated with resolutions and enantiomeric selectivities up to 2.9 and 1.33, respectively. A total of eighteen baseline separations were achieved, while seven compounds were partially separated. Vancomycin based columns operated in the polar ionic mode resulted in the greatest number of separations. Lastly, the chromatographic behaviors of similar compounds were compared based on their chemical structure and also on the chiral selectors used.     

The origin of enhanced photocatalytic decomposition of ATP on TiO2 powders as induced by surface modification with lanthanide ions: important roles of ATP adsorption to the modified surface

Surface modification of TiO₂ powders with lanthanide salts (EuCl₃ or YbCl₃) enhanced photocatalytic decomposition of ATP. In comparison with the unmodified catalyst, a 3-fold increase in the ATP decay rate was observed with TiO₂ powders as prepared in 5 mM EuCl₃ (or YbCl₃) solution. The reason was ascribed to enrichment of ATP to TiO₂ powder with the lanthanide ions. Evidence was obtained by adsorption experiments where ATP concentration was monitored after dispersing TiO₂ powders into the solution. The ATP molecules adsorbed faster to TiO₂ powder and strongly stabilized there in the presence of Yb³⁺ than otherwise.     

Less common applications of simulated moving bed chromatography in the pharmaceutical industry

Simulated moving bed (SMB) chromatography is often perceived in the pharmaceutical industry as chromatographic method for separating binary mixtures, like racemates. However, SMB can also be used for unbalanced separations, i.e. binary mixtures of varying compositions and multi-component mixtures. These less common application modes of isocratic SMB chromatography are exemplified for four different compounds (racemates and diastereomers) and discussed in view of the so-called 'triangle theory' from an industrial perspective.     

HPLC determination of organic acids, sugars, phenolic compositions and antioxidant capacity of orange juice and orange wine made from a Turkish cv. Kozan

Organic acids, sugars, phenolic compositions and antioxidant capacities of orange juice and orange wine obtained from the cv. Kozan of Turkey were determined. High-performance liquid chromatographic methods were used to identify and quantify of these compounds. Three organic acids (citric, malic and ascorbic acids) and three sugars (sucrose, glucose and fructose) were determined. The major organic acid was found as citric acid. With regard to sugars, sucrose was present in the largest amounts for orange juice and wine. A total of 13 phenolic compounds were identified and quantified in orange juice and wine, including hydroxybenzoic acids (2), hydroxycinnamic acids (5), and flavanones (6). Hesperidin, narirutin and ferulic acid were the most abundant phenolic compounds in orange juice and wine. Antioxidant activities of orange juice and wine were measured using the DPPH^• (2,2-diphenyl-1-picrylhydrazyl) assay, and the antioxidant capacity of orange juice was found to be higher than that of orange wine.     

溶剂浮选分离富集鬼箭羽中黄酮类化合物

采用溶剂浮选法分离富集鬼箭羽提取液中黄酮类化合物,并利用紫外可见分光光度法和高效液相色谱法对总黄酮及槲皮素的含量作了测定。黄酮类化合物最佳浮选条件为浮选溶剂正丁醇,溶液pH为3.0,氮气流量300 mL·min~(-1),浮选时间50 min。该法运用于鬼箭羽中黄酮化合物的分离富集,总黄酮浮选效率在70.8%～75.0%之间,浮选液旋干后总黄酮的含量是药材提取液旋干后的4.6倍;通过高效液相色谱法研究了以槲皮素为目标物的纯化分离效果,并测定其中槲皮素的含量,结果显示槲皮素浮选效率在88.9%～92.2%之间,浮选液旋干后槲皮素的含量是药材提取液旋干后的5.7倍。     

Viscous and dielectric properties of α-tocopherol and α-tocopherol acetate

This article presents the results of the shear viscosity and the dielectric relaxation measurements performed for α-tocopherol and α-tocopherol acetate, two principal compounds from the vitamin E group. The temperature dependence of the viscosity and dielectric relaxation time of the compounds can be very well reproduced with the Vogel–Fulcher–Tammann equation. It was found that for both tocopherols, the viscosity and the relaxation time attain their infinite high value (solid-like state) at the temperature of ～60 K below the transition to the glass state.     

整体柱在线固相微萃取-高效液相色谱法分析爽肤水中痕量雌激素

以甲基丙烯酸缩水甘油酯(GMA)为功能单体、乙二醇二甲基丙烯酸酯(EDMA)为交联剂,偶氮二异丁腈(AIBN)为引发剂、甲醇及正己烷(14∶5,v/v)为二元致孔剂,通过原位聚合反应制备了聚甲基丙烯酸缩水甘油酯(Poly(GMA-co-EDMA))毛细管整体柱。研究表明,制备的Poly(GMA-co-EDMA)整体柱具有良好的通透性和较低的柱压(1.5×106Pa,冲洗流速0.5 mL/min)。该整体柱对雌二醇、炔雌醇、雌酮和己烯雌酚的富集倍数分别为86、116、77和86。构建了整体柱在线微萃取接口装置,建立了整体柱在线固相微萃取-高效液相色谱(HPLC)测定爽肤水中痕量雌二醇、炔雌醇、雌酮和己烯雌酚的分析方法。该分析方法的检出限(S/N=3)为0.05~0.20μg/L。将方法应用于爽肤水中雌激素的检测,加标回收率为69.3%~111.3%,RSD5.0%。所建立的方法简单、快速、灵敏、准确,可满足爽肤水中痕量雌激素的分析。     

键合型手性固定相的研究进展

手性分离在生物医药等领域具有重要意义。高效液相色谱(HPLC)因其经济、快速、高效等特点被广泛应用于手性化合物的分离分析中。手性固定相(CSP)是HPLC实现手性分离的核心,而制备有效CSP的关键在于手性选择剂的筛选。近年来,大量文献报道了新型CSPs的制备,其中键合型CSPs因具有溶剂耐受性和较高稳定性等优点受到了广泛关注。该文对近年来以手性单分子、多糖、环糊精、大环抗生素、冠醚、杯芳烃及生物碱等为手性选择剂制备的新型键合型CSPs进行了归纳整理,并对其发展前景进行了展望。     

Facile synthesis of temperature-sensitive ABA triblock copolymers by dispersion RAFT polymerization

1. Download : Download high-res image (94KB)
2. Download : Download full-size image

     

Copper (I) Iodide-Catalyzed Solvent-Free Synthesis of α-Aminophosphonates

Abstract

A method for the synthesis of α-aminophosphonates through the three-component coupling reaction of aldehydes, amines, and diisopropyl phosphite using copper (I) iodide salt catalyst is demonstrated, The reaction is highly efficient, economic, and also environment friendly.

[Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: Table S1, Figures S1–S9.]

GRAPHICAL ABSTRACT