毛细管电中中性溶质在氰基柱上分离机理的研究

 对中性溶质在氰基柱上的毛细管电色谱（CEC）分离特征进行了研究 ,讨论了流动相中有机调节剂种类及其体积分数、缓冲液种类等对溶质迁移速率的影响。通过对样品在氰基柱上的分离行为与其在反相ODS柱和正相SI柱上的分离行为的比较 ,说明中性溶质在氰基柱上的分离机理既具有部分反相特征又具有部分正相特征。受两种机理的影响 ,在不同的操作条件下极性不同的中性溶质在氰基柱上的迁移速率差别很大 ,较一般的正相和反相电中更易出现出峰顺序变化的现象 ,也说明这种分离模式更易于进行分离选择性调节。     

毛细管离子交换电色谱的分离行为

在离子交换毛细管色谱柱上实施电色谱，并对其分离行为进行了研究，采用７５μｍ（ｉ．ｄ．）２０ｃｍ的毛细管强阳离子交换柱（３μｍ）以ＮａＨ２ＰＯ４－Ｈ３ＰＯ４缓冲液为淋洗剂，紫外柱上检测（２１４ｎｍ）考察了流动相的ｐＨ值，有机改性剂及分离电压等因素对分离的影响，研究表明，不同的ｐＨ溶质的流出次序发生改变，随着有机改性剂含量增加，溶质的保留时间减小，而电渗流却增大，同时，对分离的柱效和方法的重现性进行了     

反相毛细管电色谱中溶质保留值与溶剂化结构参数间的定量关系

利用线性溶剂化能关系（ＬＳＥＲ）方法,研究了反相毛细管电色谱（ＲＰ－ＣＥＣ）中溶质保留值与溶剂化结构参数间的定量关系。发现决定溶质在ＲＰ－ＣＥＣ中保留行为的主要因素为溶质的体积及溶质作为氢键受体的碱性大小;建立了溶质在ＲＰ－ＣＥＣ中的ｌｏｇｋ′以及保留方程ｌｏｇｋ′＝ｌｏｇｋ′ｗ－Ｓφ中ｌｏｇｋ′ｗ,Ｓ与溶质的溶剂化结构参数间的定量关系;此外,还建立了不同流动相体系间溶质的ｌｏｇｋ′ｗ和Ｓ值的换算方程。     

反相毛细管电色谱中溶质保留值与溶剂化结构参数间的定量关系

利用线性溶剂化能关系（ＬＳＥＲ）方法，研究了反相毛细管电色谱（ＲＰ－ＣＥＣ）中溶质保留值与溶剂化结构参数间的定量关系。发现决定溶质在ＲＰ－ＣＥＣ中保留行为的主要因素为溶质的体积及溶质作为氢键受体的碱性大小；建立了溶质在ＲＰ－ＣＥＣ中的ｌｏｇｋ′以及保留方程ｌｏｇｋ′＝ｌｏｇｋ′ｗ－Ｓφ中ｌｏｇｋ′ｗ，Ｓ与溶质的溶剂化结构参数间的定量关系；此外，还建立了不同流动相体系间溶质的ｌｏｇｋ′ｗ和Ｓ值的换算方程。     

MECC保留值与logP的相关性

研究了不同有机改性剂下胶束电动毛细管色谱 (MECC)中电中性化合物的保留值与其正辛醇 水分配系数 (logP)间的相关性。结果表明 :溶质在MECC中的保留值 (logk′)与logP的相关性决定于MECC体系在分配行为上与正辛醇 水体系的相似性 ,用logk′w 代替logk′并不能改善相关性 ;溶质的受质子碱性是影响相关性的最主要的溶质性质 ;使用有机改性剂可以调节溶质在MECC体系中的分配行为接近于正辛醇 水体系 ,THF是调节溶质受质子碱性的影响的最佳有机改性剂 ;要使MECC体系在溶质分配行为上全面接近于正辛醇 水体系 ,同时加入两种作用相互补充的有机改性剂可能是更好的方法     

毛细管电色谱有机流动相双二元双台阶分离

根据毛细管电色谱中溶质保留值与有机改性剂种类和浓度之间的相互关系，首次实现了毛细管电色谱有机流动相双二元双台阶分离。利用此方法分离含１２种芳香族化合物的混合样品，各组分在六次连续进样中保留时间的ＲＳＤ（％）值均在１．６５％以内，并将样品的分离时间缩短到等度洗脱方式下的三分之一。这说明该方法分离复杂样品快速、可靠。此外还推导了双二元双台阶分离方式下溶质保留值的预测公式，并对该公式的准确性进行了检验，预测值与实测值间的相对误差在５．７３％以内。     

反相毛细管电色谱中中性化合物的保留及有机改性剂对其保留值的影响

以硫脲作为电渗流标记物测定的死时间和以苯同系物线性回归方法测定的死时间为基础，将液相色谱中溶质保留值方程应用到电色谱中，得到了容量因子与二元流动相体系中有机改性剂含量之间的关系曲线；通过实验数据说明了一些极性的电中性化合物在电场作用下也会发生迁移而引起保留值的变化，且这种变化还受有机改性剂含量的影响。     

芳香化合物在氰基键合填充柱上的电色谱保留行为

在３μｍ氰基键合固定相上实施毛细管电色谱,采用乙腈／Ｔｒｉｓ反相洗脱,在７５μｍｉ．ｄ．×２５ｃｍ的毛细管柱上分离了几种芳香化合物,并对其保留行为进行了研究。利用溶剂特征显色比较法对溶质的保留进行了预测。同时还研究了乙腈的比例对电渗流的影响。对于不保留的溶质,获得了小于２．０的折合塔板数。     

反相液相色谱中保留值变化规律的研究: 同系物和柱温对保留值的影响

根据反相液相色谱保留模型和Martin方程, 采用热力学方法导出了一组包括各种色谱参数(如柱温、流动相中有机改性剂浓度以及溶质、溶剂和键合相表面烷基配体中的碳数)的线性保留方程。利用这组方程能够解释反相液相色谱中各种线性保留规律和实验现象, 并预测和实验验证了多种文献未报道的线性规律。     

多肽的反相梯度加压毛细管电色谱分离

以C18为固定相，采用电压和压力联合驱动流动相，研究反相加压毛细管电色谱分离多肽；考察了加压电色谱中，电压对带电和中性物质迁移的影响，实现了梯度加压毛细管电色谱分离6种多肽；结果表明，加压电色谱可以很好地抑制气泡形成，实验结果准确，重复性好；梯度加压毛细管电色谱在复杂样品的分离分析中，具有很大的潜力。     

Intersection Point Rule for the Retention and Mobile Phase Composition of the Homologues in Reversed-Phase Capillary Electrochromatography

Capillary Electrochromatography is a kind of micro-separation techniques newly developed in resent years. It is of both high selectivity of HPLC and high efficiency of capillary electrophoresis. This subject is being studied widely now. However, still many imperative problems need to be explored in the respect of retention rule. In this paper,based on the retention rule in RP-HPLC, the intersection point rule for the retention of homologues and the volume fraction of the organic modifier in the mobile phase in the reversed-phase capillary electrochromatography (RP-CEC) was derived, and was testified by a lot of experimental data.     

混合固定相电中溶质的输运特征

 以离子交换和反相固定相构成的混合固定相电中 ,溶质迁移在受到疏水、离子交换作用的同时 ,对于带电溶质而言 ,还受到电泳迁移的影响。根据离子独立迁移原理 ,结合过程中的多种相互作用 ,得到了描述溶质表观迁移速率与其各形态迁移速率、各种相互作用之间相互关系的理论表达式 ;讨论了混合模式电中流动相的 pH及其中的有机调节剂浓度、混合固定相配比等对电渗流的影响及不同形态溶质在柱内的输运特征。结果表明 ,在电中采用混合固定相可以在较大的 pH和有机调节剂浓度范围内得到较强且稳定的电渗流。     

Effect of Temperature on the Chromatographic Behavior of Epirubicin and its Analogues on High Purity Silica Using Reversed-Phase Solvents

The influence of temperature on the retention behavior of epirubicin and its analogues on high purity silica with reversed-phase solvents has been systematically investigated. It was found that temperature effects on retention are highly dependent on the type and concentration of organic modifier, as well as the pH of the mobile phase. In organic-rich mobile phases, the type of organic modifier plays an important role. With an aprotic solvent as modifier, retention times show anomalous increases with elevated temperature. At the same time, both efficiency and resolution are significantly improved but this is not the situation with a protic solvent as modifier. In addition, temperature shows different effects on retention time and selectivity when the pH is changed, and temperature-dependent selectivity reversal is found at higher pHs. In aqueous-rich mobile phases, regardless of the nature of the organic solvent and pH, retention of solutes drops as temperature is raised. It seems that the effect of temperature on chromatographic behavior of the solutes on bare silica using mobile phases containing various organic modifiers or pHs, results from a number of different retention mechanisms.     

Retention of ionizable compounds on HPLC. Modelling retention for neutral and ionizable compounds by linear solvation energy relationships

Summary A global LSER model that relates HPLC retention to mobile phase composition and pH is tested for a varied group of solutes, both neutral and ionizable, in a polymeric column and methanol-water mobile phases. It is compared to the local LSER model developed only for a given mobile phase, i.e., a fixed organic modifier content, and to the global LSER model set only for neutral solutes. The global LSER model for neutral and ionizable solutes requires a few supplementary parameters over the other models tested, but it accounts for retention under any experimental conditions for a given column and methanol-water mobile phases, describing properly the interactions established in the HPLC system (hydrophobicity, hydrogen-bond acidity and basicity, dipolarity/polarizability…). This paper is number 13 of a series with the same general title: “Retention of Ionizable Compounds on HPLC” published in various journals.     

Separation of acidic and neutral compounds by strong anion-exchange capillary electrochromatography dynamically modified with sodium dodecylsulfate

Summary Acidic and neutral compounds have been separated by strong anion-exchange capillary electrochromatography (SAXCEC) dynamically modified by addition of sodium dodecylsulfate (SDS). It was found that separation of neutral solutes by SAXCEC without addition of SDS is difficult because of the weak interaction of the solutes with the hydrophilic packing surface. The hydrophobicity of the packing surface increases on addition of SDS to the mobile phase, however, and the capacity of separating neutral solutes increases. Acidic solutes are retained, mainly because of the ion-exchange properties of this system. The influence of mobile phase composition, e.g. SDS concentration, ionic strength, and organic modifier fraction, on the retention of acidic and neutral solutes was investigated. Three acids and five neutral solutes were separated in only 5 min under optimized conditions, because the direction of the strong electroosmotic flow (EOF) was the same as that of electrophoretic migration of the acids under the conditions used. The repeatability of this system in terms of migration time relative standard deviation (RSD) is good—less than 0.48% for 10 consecutive runs of all the solutes tested. Column efficiencies for acids were > 125000 plates m⁻¹; those for neutral solutes varied from 25000 to 100000 plates m⁻¹.     

Chromatographic behavior of epirubicin and its analogues on high-purity silica in hydrophilic interaction chromatography

Hydrophilic interaction chromatography has been applied for the separation of epirubicin and its analogues using high-purity silica column with aqueous-organic mobile phase. Parameters affecting the chromatographic behavior of the solutes such as organic modifier, buffer pH, ionic strength and sample size, have been investigated. Of utmost importance for successful separation of these analogues is the choice of organic modifier, since it impacts both the solvent selectivity and the ionization of silica silanols as well as buffer solution, and consequently the retention behavior of solutes. Acetonitrile was shown to offer superior separation of these analogues to methanol, isopropanol or tetrahydrofuran. Results of the effects of organic modifier, buffer pH and ion strength indicate that the retention mechanism is a mixed-mode of adsorption and ion exchange. In addition, an irreversible adsorption of these compounds was found on silica in the weakly acidic or neutral mobile phases, and the effect of various factors on irreversible adsorption was also preliminarily discussed. More significantly, these basic compounds have exhibited peaks with a slanted front and a sharp tail, a typical overloading peak profile belonging to the behavior of competitive anti-Langmuir isotherm by increasing the sample size at the experimental conditions.     

固定化有机改进剂RP－HPLC固定相的研究

通过在ＲＰＨＰＬＣ固定相Ｃ１８表面键合氨基硅烷，引入氨基基团，将有机改进剂固定至硅胶键合相表面，克服了固定相表面硅羟基对含氮有机化合物的不可逆吸附。以最简单的ＣＨ３ＯＨ－Ｈ２Ｏ洗脱体系即能获得含氮有机物的最佳分离，从而可简化分离操作，提高柱寿命，降低分离成本。     

Lipophilicity characterization by reversed-phase liquid chromatography of some furan derivatives

Lipophilicity is one of the properties which influences the partition of a substance in biological media. The present study reports on the chromatographic behaviour of a newly synthesised series of furan derivatives by RP-HPLC and RP-TLC, with methanol-water and acetonitrile-water as mobile phases, in order to establish if the linear relationships between the retention parameters (log k, R(M)) and the concentration of organic modifier in the mobile phase, phi, allows the extrapolation procedure. Good correlations between the retention parameters were obtained by RP-HPLC and RP-TLC, and the concentration of organic modifier (methanol, acetonitrile) in the mobile phase was established for the studied furan derivatives. However, for the discussed compounds, acetonitrile has a lower sensitivity to changes in the structures. A good correspondence was obtained between the extrapolated parameters for the methanol-water mobile phase when using RP-HPLC and RP-TLC. However, stronger interactions occur in RP-TLC between the compounds and the residual silanol groups than in RP-HPLC.     

固定化有机改进剂RP－HPLC固定相的研究

通过在ＲＰＨＰＬＣ固定相Ｃ１８表面键合氨基硅烷，引入氨基基团，将有机改进剂固定至硅胶键合相表面，克服了固定相表面硅羟基对含氮有机化合物的不可逆吸附。以最简单的ＣＨ３ＯＨ－Ｈ２Ｏ洗脱体系即能获得含氮有机和的最佳分离，从而可简化分离操作，提高柱寿命，降低分离成本。