聚硅氧烷冠醚做气相色谱固定液的研究

自从Pedersen首次发现冠醚能和金属离子形成稳定的络合物之后,冠醚在分析化学中得到了广泛的应用。它在液相色谱中的应用开发较早。低分子冠醚在气相色谱中的应用在1985年首先由李如松报道。Zagorevskaya等人则把低分子冠醚涂渍在碳分子筛上分离各种烷烃、芳烃和含氯化合物。金永浩等用武汉大学环科系合成的漆酚冠醚涂渍成毛     

气相色谱固定相研究进展

介绍了气相色谱固定相的研究进展，重点对各种冠醚固定相的特征，应用和分离机理进行了评述。     

双苯甲酰胺冠醚固定相的合成及毛细管柱气相色谱性能…

合成了一种新型的双苯甲酰胺冠醚固定相：（１Ｓ，２Ｓ）－１－（对苯甲酰胺基）苯基－２－苯甲酰胺基－１６－冠－５，其结构经红外光 谱、核磁共振、质谱及元素分析数据证实这种固定相的柱交、热稳定性、极性及选择性等色谱特性。该类固定相对极性位置异构分离效果良好。由于冠醚上引入苯甲酰胺取代基，因而对苯胺类及不经衍生化 碱性化合物能特殊选择性地分离。     

手性冠醚聚硅氧烷固定相的制备及其气相色谱性能

以Ｄ－甘露醇和）＋）－２－氨基－１－丁醇为手性源，合成了两种含末端烯基的手性冠醚。通过硅氢加成反应制备了两种新型手性冠醚聚氧烷相色谱固定相ｃｈｉｒａｓｉｌ－ｍａｎ－１８Ｃ６－２５和ｃｈｉｒａｓｉｌ－ａｚａ－１５Ｃ－２５。     

气相色谱手性固定相进展

1966年Gil-Av等人首次用手性固定相在毛细管柱上分离了氨基酸对映体。至今这种方法已发展为研究和分离对映体的一种重要技术,并愈来愈多地用于天然产物绝对构象(外激素、香料成分等)的测定,不对称选择合成中对映体纯度及过剩量测定,手性药物中对映体纯度的测定,手性化合物在化学转移机理等方面的研究。目前气相色谱中用于分离对映体的     

毛细管柱气相色谱固定液的新进展

本文作者曾对近年来用于毛细管柱的气相色谱固定液作过一些评述。但近二年又有几类新的毛细管柱用气相色谱固定液问世。本文将对这两年出现的几类新固定液作一简要概述。     

八种冠醚固定液的McReynolds常数的研究

冠醚在气相色谱分析中的应用研究已有论文发表。本文测定了八种冠醚固定液的McReynolds常数,并讨论了它们的色谱性质。 1 实验 1.1 主要仪器与试剂 103气相色谱仪,上海分析仪器厂,φ4×1 000 mm不锈钢柱;电子秒表(±0.01 s);Chromosorb G-AW-DMCS(60～80目,美国);正构烷烃,     

套索冠醚固定相的气相色谱研究

用一种新合成的套索冠醚Ｎ，Ｎ′－双（乙酰苄胺）－二氮杂－１８－冠－６作为固定相，涂渍在弹性石英毛细管内，测其柱效、惰性、热稳定性、平均极性及选择性等性质。实验表明，它具有良好的色谱性能，中等极性，分离选择性高，适用于对醇、卤代烃、芳香烃等各类异构体的分离，并从分子结构和热力学参数等探讨了保留机理。     

毛细管气相色谱用固定液的进展

一、前言 自从1979年弹性石英毛细管柱问世之后.毛细管气相色谱得到了迅速的发展。以毛细管柱代替填充柱的趋势日益明显.特别是1983年大内径厚液膜毛细管柱的发展和应用使这种趋势更加肯定了。当然目前在国内填充柱气相色谱仍在例行分析中占主导地位,但是随着毛细管色谱技术在国内的进一步发展,填充柱会逐步地被毛细管柱所取代。     

Synthesis and characterization of β-cyclodextrin modified hyperbranched carbosilane as stationary phase for GC

A new β-cyclodextrin modified hyperbranched carbosilane stationary phase for gas chromatography was synthesized by substituting the -OH groups ofβ-cyclodextrin with hyperbranched carbosilane and was coated on the inner wall of fused silica capillary column for gas chromatography.The chromatographic behaviors of the stationary phase were studied.The initial testing results showed mat it possessed good separation abilities for several kinds of mixtures,such as benzenes,acrylates,ketones and alkylchlorides.     

Capillary electrochromatography of methylated benzo[a]pyrene isomers. II. Effect of stationary phase tuning

For Part II of our ongoing study, we present a strategy for stationary phase optimization for the capillary electrochromatographic (CEC) separation of the 12 methylated benzo[a]pyrene (MBAP) isomers. Utilizing the optimum mobile phase conditions from Part I of our study as a guide, seven commercially available stationary phases have been evaluated for their ability to separate highly hydrophobic MBAP isomers. Ranging in design from high-performance liquid chromatography (HPLC) to CEC application, each phase was slurry packed in house and tested for CEC suitability and performance. Several stationary phase parameters were investigated for their effects on MBAP separation including bonding type (monomeric or polymeric, % carbon loading, surface coverage), pore size, particle size, and type of alkyl substituent. In this manner, the present state of commercially available packings has been assessed in our laboratory. Utilizing the optimum polymeric C18-5 microm-100 A-PAH stationary phase, the effects of CEC packed bed length and capillary inside diameter (I.D.) were also evaluated. A 50 microm I.D. capillary, 25 cm packed bed length and 75% (v/v) acetonitrile, 12.5 mM Tris, pH 8.0, 20 degrees C at 30 kV, provided resolution of 11 out of 12 MBAP isomers thus showing the effectiveness of CEC for analysis of structurally similar methylated polyaromatic hydrocarbons.     

Separation of positional isomers on polymeric calix[4]arene-siloxane stationary phases in capillary GC

Summary Poly(p-tert-butyldimethoxydipropyloxycalix[4]arene-tetramethyldisiloxane) (TBCX-TMDS) and poly(dimethoxydipropyloxycalix[4]arene-tetramethyl-disiloxane) (CX-TMDS), have been prepared and used as stationary phases for isothermal capillary gas chromatographic separations of positional isomers. Retention factors and separation factors for the isomers were measured. The isomers investigated were well-resolved on the two phases. Retention of all the solutes investigated is greater on TBCX-TMDS than on CX-TMDS, probably because of extra dispersive interactions of the solutes with thetert-butyl groups of the phase. Separation factors for closely-eluting isomer pairs are similar on the two phases. This seems to indicate either that the solutes are retained by non-inclusion processes or that if the isomer molecules do enter the cavity of the calixarene, i.e. the solute is retained by inclusion, thetert-butyl groups do not play a role in discriminating between the isomers.     

Separation of polychlorodibenzo-p-dioxins and-dibenzofurans on the new polar stationary phase DB DIOXIN

Summary A complete assignment of the polychlorodibenz-p-dioxins (CL_xDD) and polychlorodibenzofurans (Cl_xDF) (x=4–8) separated on the new polar polysiloxane phase which contains 44% methyl, 28% phenyl, 20% cyanopropyl and 8% polyoxyethylene (Carbowax) groups (DB DIOXIN) is presented.     

Preparation and evaluation of 1,3-alternate 25,27-bis-(pentafluorobenzyloxy)-26,28-bis-(3-propyloxy)-calix[4]arene-bonded silica gel high performance liquid chromatography stationary phase

A 1,3-alternate 25,27-bis-(pentafluorobenzyloxy)-26,28-bis-(3-propyloxy)-calix[4]arene-bonded silica gel stationary phase (CalixBzF₁₀) was synthesized, structurally characterized, and used as a selector in liquid chromatography. The selectivity study of this phase was done by using fluorine-containing compounds (fluorobenzenes, fluoro-pyrimidine bases), as well as non-fluorinated analytes (non-steroidal anti-inflammatory drugs, sulfonamides, xanthines and polynuclear aromatic hydrocarbons). The effects of organic modifiers on the retention of various compounds possessing basic, acidic and neutral characteristics were studied. It was shown that only basic analytes exhibit a “U-shaped” retention profile and that retention depends on the mobile phase pH. Selectivity comparisons of the novel phase vs. the 1,3-alternate 25,27-bis-(benzyloxy)-26,28-bis-(3-propyloxy)-calix[4]arene phase (CalixBz) were performed. The retention mechanism is also discussed. The results indicate that the fluorinated calixarene stationary phase behaves like reversed-phase packing material; however, fluorine–fluorine interactions seem to be involved in the separation process of fluorine-containing analytes.     

Development and application of a new 25,27‐bis(l‐phenylalaninemethylester‐N‐carbonylmethoxy)‐26,28‐dihydroxy‐para‐tert‐butylcalix[4]arene stationary phase

A 25,27‐bis(l ‐phenylalaninemethylester‐N‐carbonylmethoxy)‐26,28‐dihydroxy‐ para‐tert‐butylcalix[4]arene‐bonded silica gel stationary phase was synthesized, structurally characterized and used for LC. Its separation mechanism was studied and compared with octadecyl‐bonded stationary phase, as well as our previously prepared para‐tert‐butylcalix[4]arene‐1,2‐crown‐4 stationary phase. Meanwhile, the chromatographic behaviors were investigated by using polycyclic aromatic hydrocarbons, monosubstituted benzenes, anilines, phenols, Tanaka tests solutes, fluoroquinolones, and flavonoids as probes. Mechanisms involved in the chromatographic separation included hydrophobic, π‐π and π‐electron transfer, hydrogen bonding, and inclusion interactions. Moreover, the column was successfully employed for the analysis of the illegal additive of melamine in milk product.     

Studies on the New Constituents of Sal via Miltiorrhiza Bunge

Two novel constituents were isolated from the roots of Chinese medicinal herbs, Salvia miltiorrhiza. Their structures were determined by spectroscopic technique. The compounds were named 13,14-dihydroxy-15-methyl-benzo[2,3-a]-7,7-dimethyl-12-oxa-tricyclo[4,4,21.4,0]dodecane(1) and 16-methyl-tropono[2,3-c]-7,7-dimethyl-12-oxa-tricyclo[4,4,21.4,0]dodecane(2).     

Enantioselective behaviour of ethylated γ-cyclodextrins as GC stationary phases for chlorinated pesticides and phase characterisation by HPLC

Summary Small composition changes can influence the enantiomeric selectivity of alkylated cyclodextrins used as stationary phase in high resolution gas chromatography. A method is presented for the characterisation of such cyclodextrins using high performance liquid chromatography combined with evaporative light scattering and mass spectrometric detection (atmospheric pressure chemical ionisation in the positive ion mode). The method was applied to different batches of octakis (2,3,6-tri-O-ethyl)-γ-cyclodextrins (TEG-CD). Some showed a very good enantiomer selectivity for chlorinated pesticides. Separation evaluations were carried out with an improved test mixture containing selected, partly enantiomer enriched pesticides. Capillaries based on underethylated TEG-CD with up to 4 free OH groups dissolved in OV 1701-OH allowed the separation of α-HCH, o,p’-DDT, compounds of technical chlordane (cis-and trans-chlordane, U82, MC5, MC7, MC8) as well as chlordane metabolites (cis- and trans-heptachlor epoxide, oxychlordane) into enantiomers.     

Liquid chromatographic behavior of two alanine‐substituted calix[4]arene‐bonded silica gel stationary phases

Two new kinds of alanine‐substituted calix[4]arene stationary phases of 5,11,17,23‐p‐tert‐butyl‐25,27‐bis(l ‐alanine‐methylester‐N‐carbonyl‐methoxy)‐26,28‐dihyroxycalix[4]arene‐bonded silica gel stationary phase (BABS4) and 5, 11, 17, 23‐p‐tert‐butyl‐25,26,27,28‐tetra(l ‐alanine‐methylester‐N‐carbonyl‐methoxy)‐calix[4]arene‐bonded silica gel stationary phase (TABS4) were prepared and characterized in the present study. They were compared with each other and investigated in terms of their chromatographic performance by using polycyclic aromatic hydrocarbons, disubstituted benzene isomers, and mono‐substituted benzenes as solute probes. The results indicated that both BABS4 and TABS4 exhibited multiple interactions with analytes. In addition, the commonly used Tanaka characterization protocol for the evaluation of commercially available stationary phases was applied to evaluate the properties of these two new functionalized calixarene stationary phases. The Tanaka test results were compared with Zorbax Eclipse XDB C₁₈ and Kromasil phenyl columns, respectively. BABS4 has stronger hydrogen‐bonding capacity and ion‐exchange capacity than TABS4, and features weaker hydrophobicity and hydrophobic selectivity. Both of them behave similarly in stereoselectivity. Both BABS4 and TABS4 are weaker than C₁₈ and phenyl stationary phases in hydrophobicity and hydrophobic selectivity.     

Preparation,characterization and application of a new 25,27‐bis‐[2‐(5‐methylthiadiazole)thioethoxyl]‐26,28‐dihydroxy‐para‐tert‐butyl calix[4]arene stationary phase for HPLC

A new para‐tert‐butylcalix[4]arene column containing thiadiazole functional groups was prepared and used for the separation of polycyclic aromatic hydrocarbons, phenolic compounds, aromatic amines, benzoic acid and its derivatives by high‐performance liquid chromatography (HPLC). The effect of organic modifier content in the mobile phase on retention and selectivity of these compounds were investigated. The results indicate that the stationary phase behaves like reversed‐phase packing. However, hydrogen bonding, π–π and inclusion interactions seem to be involved in the separation process. The column has been successfully employed for the analysis of clenbuterol in pork and pig casing; the limit of detection and the limit of quantitation for this method by HPLC‐UV detection was 0.03 and 0.097 μg/mL, respectively; the method is demonstrated to be suitable and a competitive alternative analytical method for the determination of clenbuterol.