Profiling of Permeable Compounds in Ligusticum chuanxiong by Biopartitioning Micellar Chromatography

The potential of biopartitioning micellar chromatography (BMC) for screening and analysis of traditional Chinese medicines (TCM) for permeable compounds has been investigated by chromatography of methanolic extracts of Ligusticum chuanxiong, as example. Six other ordinary TCM were also studied. Results showed that more than ten components of Ligusticum chuanxiong extract are significantly retained in BMC. According to relationships between retention in BMC and oral drug absorption, cell-membrane permeability, and blood–brain barrier permeability, the cell-membrane permeability and absorption properties of the permeable components of Ligusticum chuanxiong extract could be predicted from their retention in BMC. Effects on the chromatography of components of Ligusticum chuanxiong methanolic extracts of column temperature, mobile phase pH, and concentration of Brij 35 in the mobile phase are also discussed.     

Solvatochromic Linear Solvation Energy Relationships (LSER) for Solubility of Gases in Various Solvents by Target Factor Analysis

A linear solvation free energy relationship has been conducted to study the effects of solvent and solute properties on the free energy of solvation of inert gases and normal alkanes in different solvents. Factor analysis combined with target factor analysis was used to identify and quantify the factors controlling the variation of free energies of solvation, without the need to postulate any priori hypothetical method. Factor analysis of the solvation data revealed that there are two factors affecting the solubility of both types of gases in non‐polar as well as polar solvents. Target testing of the solvent parameters indicated that the Hildebrand solubility parameter of solvents is the major factor controlling the solubility of gases. Moreover, it was found that the coefficient of the Hildebrand solubility parameter in the linear solvation free energy equations has linear correlation with energy of vaporization and Lennard‐Jones force parameter of inert gases and number of carbon atoms and energy of vaporization of normal alkanes.     

Study of Quantitative Structure-Retention Relationships for s-Triazine Derivatives in Different RP HPTLC Systems

JPC – Journal of Planar Chromatography – Modern TLC - Quantitative structure-retention relationships (QSRR) have been used to study the chromatographic behavior of some s-triazines....     

Linear Solvation Energy Relationships in the Determination of Specificity and Selectivity of Stationary Phases

The retention of fifty structurally different compounds has been studied using linear solvation energy relationships. Investigations were performed with the use of six various stationary phases with two mobile phases (50/50 % v/v methanol/water and 50/50 % v/v acetonitrile/water). Packing materials were home-made and functionalized with octadecyl, alkylamide, cholesterol, alkyl-phosphate and phenyl molecules. This is the first attempt to compare all of these stationary phases synthesized on the same silica gel batch. Therefore, all of them may be compared in more complex and believable way, than it was performed earlier in former investigations. The phase properties (based on Abraham model) were used to the classification of stationary phases according to their interaction properties. The hydrophilic system properties s, a, b indicate stronger interactions between solute and mobile phase for most of the columns. Both e and v cause greater retention as a consequence of preferable interactions with stationary phase by electron pairs and cavity formation as well as hydrophobic bonds. However, alkyl-phosphate phase has different retention properties, as it was expressed by positive sign of s coefficient. It may be concluded that most important parameters influencing the retention of compounds are volume and hydrogen bond acceptor basicity. The LSER coefficients showed also the dependency on the type of organic modifier used as a mobile phase component.

     

Linear Solvation Energy Relationships in the Determination of Specificity and Selectivity of Stationary Phases

The retention of fifty structurally different compounds has been studied using linear solvation energy relationships. Investigations were performed with the use of six various stationary phases with two mobile phases (50/50?% v/v methanol/water and 50/50?% v/v acetonitrile/water). Packing materials were home-made and functionalized with octadecyl, alkylamide, cholesterol, alkyl-phosphate and phenyl molecules. This is the first attempt to compare all of these stationary phases synthesized on the same silica gel batch. Therefore, all of them may be compared in more complex and believable way, than it was performed earlier in former investigations. The phase properties (based on Abraham model) were used to the classification of stationary phases according to their interaction properties. The hydrophilic system properties s, a, b indicate stronger interactions between solute and mobile phase for most of the columns. Both e and v cause greater retention as a consequence of preferable interactions with stationary phase by electron pairs and cavity formation as well as hydrophobic bonds. However, alkyl-phosphate phase has different retention properties, as it was expressed by positive sign of s coefficient. It may be concluded that most important parameters influencing the retention of compounds are volume and hydrogen bond acceptor basicity. The LSER coefficients showed also the dependency on the type of organic modifier used as a mobile phase component.     

Quantitative Structure-Retention Relationship and 3D Molecular Modeling Studies of the Unusual Chromatographic Behavior of Triphenylmethane Derivatives in RPTLC Systems

JPC – Journal of Planar Chromatography – Modern TLC - Dual retention behavior is observed for triphenylmethane (TPM) derivatives in RPTLC on silica gel plates when the composition of...     

正相薄层色谱中常见人参皂甙结构与保留值之间关系的初步研究(英文)

 在硅胶薄层板上用氯仿-乙酸乙酯-甲醇-水(体积比为15∶40∶22∶10)作展开剂,测定了常见人参皂甙的Rf值。为了研究它们的结构与保留值之间的关系,对它们的17种结构参数进行了计算。除了拓扑指数和理化参数外,引入了代表构成人参皂甙的母体化合物种类并反映它们分子极性特征的新参数“E”。通过相关分析优化选出范德华分子表面积AW、拓扑指数0B和参数E,建立了多参数线性回归方程,较好地描述了在正相薄层色谱中常见人参皂甙结构与保留值之间的关系,并与人工神经网络方法进行了比较。     

Evaluation of Retention Factors for Nine Solutes with Ionic Liquid Additives via Linear Solvation Energy Relationships

<正>A linear solvation energy relationships(LSERs) model was used to examine the fundamental chemical interactions governing the retention of 9 organic compounds on a C_(18) column by means of reversed-phase high performance liquid chromatography(RP-HPLC).Three ionic liquids,1-hexyl-3-methylimidazolium tetrafluoroborate ([Hmin][BF_4]),1-butyl-3-methylimidazolium tetrafluoroborate([Bmin][BF_4]) and 1-octyl-3-methylimidazolium tetrafluoroborate([OMIm][BF_4]) as additives,were added to a methanol-water mobile phase.The effects of these three ionic liquids additives on the retention of nine organic compounds were investigated,and a comparison between the predicted and experimental retention factors was made via the LSERs model,which indicated that the LSERs model could be used to reproduce the experimental retention factors of the solutes under different mobile phase conditions. It is also a useful tool for modeling the interactions of the solutes between the stationary and mobile phases and evaluating the retention characteristics of HPLC.     

Quantitative Structure-Retention Relationship Modeling of the Retention Behavior of Guanidine and Imidazoline Derivatives in Reversed-Phase Thin-Layer Chromatography

JPC – Journal of Planar Chromatography – Modern TLC - The quantitative structure-retention relationship (QSRR) study has been performed in order to investigate the retention behavior of...     

分子相似性方法用于药物反相色谱定量结构色谱保留关系的研究

 应用分子相似性方法研究药物的反相色谱定量结构 色谱保留关系 (QSRR)。在全面考察药物的分子结构参数的基础上 ,采用分子相似性计算方法 ,将化合物结构信息变量转换为相似系数变量 ,并结合人工神经网络技术 ,对 16 2种药物进行反相色谱定量结构与色谱保留关系的研究。成功地应用分子相似性方法实现了对容量因子这一色谱保留参数的预测 ,建立了物理意义明确、预测能力较强的分子结构参数与反相色谱流动相溶剂强度和容量因子之间的定量关系模型 ,实验验证的结果也比较理想。     

基于反相高效液相色谱法构建 QSRR 模型测定萘类及蒽醌类化合物的正辛醇-水分配系数

正辛醇-水分配系数(Kow )是评价药物毒性、活性及跨膜转运等的重要参数,但直接测定法实验过程复杂。本研究采用反相高效液相色谱(RP-HPLC)法,以甲醇-水为流动相,以29种已知 Kow的酸性和中性苯系物及萘类、醌类衍生物为模型化合物,以保留时间两点校正法( DP-RTC)校正保留时间,并由 Snyder-Soczewinski方程得100%水相保留因子(kw ),建立了表观正辛醇-水分配系数 Kow＂与 kw 的定量关系(Quantita-tive structure-retention relationship, QSRR)模型,并对模型进行了内、外部验证。结果表明,不同 pH 下的 QSRR模型线性相关性 R2=0.974~0.976,内部验证( R2cv =0.970~0.973)和外部验证结果(6种验证化合物,1.4%≤相对误差(RE)≤7.9%)令人满意,与考虑了分子结构参数后建立的线性溶剂化能模型(LSER)相比无差异。将建立的 QSRR 模型应用于11种萘类和蒽醌类化合物的 Kow测定,并与软件计算值、摇瓶法实验值比较,结果表明,本方法准确性更高,且简单快捷,可用于快速准确预测复杂混合物体系中组分的 Kow。     

Selectivity Control in Micellar Electrokinetic Chromatography by Modification of Micellar Surface with Cyclohexanol

Abstract

The effect of cyclohexanol added to the micellar solution of sodium dodecyl sulfate in the micellar electrokinetic chromatography of several aromatic compounds was investigated. Cyclohexanol (0.05–-0.10 M) diminished the capacity factors (k') of the solutes possessing hydrophilic functional groups which were solubilized near the micellar surface, whereas little changed the k' of the hydrophobic solutes solubilized in the micellar core. This selective effect was ascribed to the saturation of the micellar surface with cyclohexanol.     

Study of the Effect of Mobile Phase Additives on Retention in Reversed Phase HPLC Using Linear Solvation Energy Relationships

Linear solvation energy relationships (LSERs) were used to delineate which specific intermolecular interactions are responsible for changes in retention for a variety of well characterized analytes when acidic and basic additives were used in reversed phase HPLC. The effects of trifluoroacetic acid, triethylamine and a combination of trifluoroacetic acid and triethylamine on the LSERs were compared to those observed in the absence of additives. These effects were examined using four different mobile phase modifiers and five different stationary phases. Trifluoroacetic acid alone and in combination with triethylamine produced LSER regression coefficients nearly identical to those obtained with no additive present in the mobile phase. Triethylamine alone produced different LSER regression coefficients from the other systems unless the mobile phase contained trifluoroethanol as the mobile phase modifier, or the stationary phase consisted of a polymeric support.     

全自动定量胶束电动毛细管色谱检测化妆品中5种防腐剂

研制了一套全自动高精度可控温定量毛细管电泳仪,通过引入10 n L的进样阀实现定量进样,配合自主研制的自动进样系统和恒温液冷系统,以提高毛细管电泳的定量重复性和准确性。采用全自动定量胶束电动毛细管色谱(q MEKC)测定市售化妆品中苯甲酸、对羟基苯甲酸甲酯(MP)、对羟基苯甲酸乙酯(EP)、对羟基苯甲酸丙酯(PP)、对羟基苯甲酸丁酯(BP)5种防腐剂的含量,优化了分析条件。以15 mmol/L硼砂-100 mmol/L SDS混合溶液(p H 9.3)为背景电解质溶液,工作电压为20 k V,5种防腐剂在该条件下得到了良好的分离和定量结果,峰面积的相对标准偏差(RSD)小于2%。该方法快速、准确,对于化妆品中防腐剂的限用量控制具有重要意义。     

对-叔丁基-杯[4]芳烃键合硅胶及其它硅胶基质键合固定相的色谱保留性质

利用线性溶剂化能相关,在相同色谱条件下,研究了对-叔丁基-杯[4]芳烃键合硅胶固定相与其它硅胶基质键合固定相的反相色谱行为。结果表明,对-叔丁基-杯[4]芳烃键合硅胶固定相和其它固定相在保留机理上有很大不同。控制溶质保留的两个主要因素不是溶质的体积和氢键受体碱性,而是溶质的过剩摩尔折光率和氢键给体酸性。r系数值较大说明π-π作用对溶质的保留贡献较为明显,说明该新固定相对高极化率溶质如稠环芳烃具有较高的选择性。     

Effect of Preferential Solvation on the Thermodynamic Properties of Antidepressant Drug Trazodone in Aqueous Ethanol: Linear Free‐Energy Relationships

Dissociation constants (pK_a) of trazodone hydrochloride (TZD⋅HCl) in EtOH/H₂O media containing 0, 10, 20, 30, 40, 50, 60, 70, and 80% (v/v) EtOH at 288.15, 298.15, 308.15, and 318.15 K were determined by potentiometric techniques. At any temperature, pK_a decreased as the solvent was enriched with EtOH. The dissociation and transfer thermodynamic parameters were calculated, and the results showed that a non‐spontaneous free‐energy change (Δ_dissG^o>0) and unfavorable enthalpy (Δ_dissH^o>0) and entropy (Δ_dissS^o<0) changes occurred on dissociation of trazodone hydrochloride. The free‐energy change or pK_a varied nonlinearly with the reciprocal dielectric constant, indicating the inadequacy of the electrostatic approach. The dissociation equilibria are discussed on the basis of the standard thermodynamics of transfer, solvent basicity, and solute‐solvent interactions. The values of Δ_transG^o and Δ_transH^o increased negatively with increasing EtOH content, revealing a favorable transfer of trazodone hydrochloride from H₂O to EtOH/H₂O mixtures and preferential solvation of H⁺ and trazodone (TZD). Also, Δ_transS^o values were negative and reached a minimum, in the H₂O‐rich zone that has frequently been related to the initial promotion and subsequent collapse of the lattice structure of water. The pK_a or Δ_dissG^o values correlated well with the Dimroth‐Reichardt polarity parameter E_T(30), indicating that the physicochemical properties of the solute in binary H₂O/organic solvent mixtures are better correlated with a microscopic parameter than the macroscopic one. Also, it is suggested that preferential solvation plays a significant role in influencing the solvent dependence of dissociation of trazodone hydrochloride. The solute‐solvent interactions were clarified on the basis of the linear free‐energy relationships of Kamlet and Taft. The best multiparametric fit to the Kamlet‐Taft equation was evaluated for each thermodynamic parameter. Therefore, these parameters in any EtOH/H₂O mixture up to 80% were accurately derived by means of the obtained equations.     

酸性磷型萃取剂萃取稀土的线性自由能关系

用线性回归分析探讨了各种类型和结构的一元酸性磷型萃取剂萃取稀土的表观萃取平衡常数 (lgKex)与萃取剂分子中取代基的电子效应参数 (ΣσΦ)和空间效应参数 (Συ )之间的相关关系。结果表明 ,对于这类萃取体系 ,线性自由能关系式lgKex=ρΣσΦ ψΣυ h 普遍成立。据此讨论了萃取剂结构与萃取性能之间的定量关系 ,可用于初步预测一定结构的这类萃取剂萃取稀土的lgKex值。     

Determination of Saikosaponins in Bupleuri Radix by Micellar Electrokinetic Chromatography with Experimental Design

The important pharmacological components of Bupleuri radix include saikosaponins a–d. A multivariable approach with experimental design was employed in this study to determine four saikosaponins in different species of Bupleuri radix by cyclodextrin-modified micellar electrokinetic chromatography. Compared to traditional multiple-parameter investigations, the current experimental design can shorten the time necessary for method development, and the multivariable approach can be used to evaluate the separation capability of the method and to explore the interactions of the different parameters. The significant influences of two experimental variables, including the concentration of γ-cyclodextrin and the percentage of methanol, on the responses were investigated using chromatographic resolution statistics. The optimized conditions were as follows: 25?mM of borate (pH 9.18) containing 50?mM of sodium dodecyl sulfate, 5?mM of γ-cyclodextrin, and 15% methanol (v/v) as running buffer. After the separation conditions were optimized and good resolution was acquired, solid phase extraction was performed to reduce the interference of crude extracts of Bupleurum kaoi and Bupleurum chinense DC. The simple and rapid analytical method was successfully applied, allowing for the determination of four saikosaponins and the identification of species of Bupleuri radix.     

Linear Free Energy Relationships in SNAr Reactions of Aryl and Diaryl N-Anions with Aryl Halides

A good correlation has been established between the Brønsted coefficients _{N u c} and _{o x} for reactions of aryl-containing N-anions with various aryl halides. This correlation reflects the dependence of the internal barrier of aromatic nucleophilic substitution on the oxidation potentials of nucleophiles.     

Simultaneous Determination of Phenolic Additives in Cosmetics by Micellar Electrokinetic Capillary Chromatography with Electrochemical Detection

A micellar electrokinetic capillary chromatography method with electrochemical detection (MECC‐ED) has been developed for the simultaneous determination of eight phenolic additives, including propyl gallate (PG), tert‐butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), methylparaben (MP), ethylparaben (EP), propylparaben (PP) and butylparaben (BP) in cosmetic products. Method development involved optimization of the working electrode, the pH value of running buffer, the concentration of sodium dodecyl sulfate (SDS), the separation voltage, and the sample injection time. Under the optimum conditions, all analytes can be well separated within 26 min at the separation voltage of 18 kV in a 9 mmol·L^?1 sodium dodecyl sulfate (SDS) ?60 mmol·L^?1 borate running buffer (pH 8.0). A 300 μm diameter carbon disk electrode generated good response at +0.90 V (vs. SCE) for all analytes. Linearity of the present method was over three orders of magnitude of analyte concentration with detection limits (S/N=3) ranging from 1.1×10^?7 to 1.2×10^?6 g·mL^?1 for all analytes. This proposed method has been successfully applied to the simultaneous determination of the above additives in commercial cosmetics, and the assay results were satisfactory.