塔板理论对柱内和柱外浓度分布曲线的描述

使用Visual Basic和QBasic程序，分别在Excel和DOS上，在不做任何化简的情况下，对塔板理论描述的柱内和柱外组分浓度分布进行了研究。发现符合线性分配的样品组分在色谱柱内存在3种不同的浓度分布形态，在色谱柱外则都是拖尾峰形态。分析了不同分配比对柱内和柱外浓度分布曲线最高点和次高点的影响。     

10°锥角台锥型液相色谱柱尺寸等比例放大和柱内谱带流型的可视化研究

摘要利用改进的可视化装置, 研究了10°锥角的台锥型液相色谱柱内的谱带流型与柱参数变化的关系. 将有机玻璃柱管加工成内圆台外方型的一体结构, 选择折射率一致的色谱固定相硅胶和流动相环己烷, 使整个色谱柱成为高度清晰的透明体, 能直接观察柱中彩色样品谱带的动态三维流型. 研究结果表明, 在实验条件范围内, 流动相流速对谱带流型无影响, 填料的形状和性质对塞子状流型有一定程度的影响. 比较了柱长为5cm和等比例放大后柱长为10cm锥型柱内的流型, 发现放大后的锥型柱内仍然保持塞子状流型, 总柱效等比例增加. 表明继续按比例放大成为工业规模色谱柱后仍能保持塞子状流型.     

毛细管电色谱中超长进样溶质在柱内的分布特征

在毛细管电色谱中，对浓度极稀的样品，通过加长进样时间，控制操作条件可能有效地实现溶质在柱内的富集，提高检测灵敏度。本文根据驰豫理论的基本原理，从理论上探讨了进样过程中溶质在固定相上的吸附作用对其分布的影响规律。理论和试验皆证明：采用超过时间进样的方法，通过控制进样区带与运行区带中有机调节剂浓度、离子强度等条件，导致溶质在区带界面处的速度产生阶跃，能够使中性溶质仅保留在柱内较窄的区带中，这一过程类似于完成一次固相微萃取过程，能够达到较好的富集效果。对于药物安息香达到了超过2000倍的富集效果。     

铝酸钠溶液晶种分解附聚过程研究

苛性钠浓度Na2Ok=140g·L-1,苛性比αk=1.37的铝酸钠溶液中,在种子比Ks=0.25,温度T=76℃的条件下对附聚过程进行了研究.通过粒度分布对时间变化的分析,探讨了晶种附聚过程的规律.实验发现细粒子在短时间内就可以附聚完全.两相邻时间段粒度分布曲线的交点rp在30u m左右,在一定时间内rp值基本保持不变,但在整个分解时间内略有右移.rp以下的粒子附聚可能性大,rp以上的粒子附聚可能性小.     

制备型液相色谱动态轴向压缩柱技术和应用

综述了动态轴向压缩技术装填液相色谱柱的原理、装置及装置设计的发展状况,对动态轴向压缩装填过程和柱性能的影响因素如柱长、填料和调浆溶剂的性质、压缩压力进行了分析,讨论了柱内密度分布不均、柱壁效应两种现象和解决的办法,评价了这种技术的优缺点,介绍了其应用、发展现状与前景。引用文献50篇。     

气流床煤气化炉内流动、混合与反应过程的研究进展

气流床气化过程涉及高温高压下湍流多相流动与复杂化学反应过程的相互作用,涵盖喷嘴雾化与弥散、复杂多相射流流动、炉内湍流混合、复杂气化反应、火焰结构及温度分布等诸多方面,是世界各国研究的热点.对近年来世界各国在气流床气化过程研究上取得的进展进行了综述,包括喷嘴雾化与颗粒弥散机理与雾化过程的影响因素、撞击流驻点偏移规律和撞击面振荡规律、撞击火焰结构与炉内三维温度场、典型煤种气化反应特性与石油焦气化特性以及气流床气化过程模拟.对气流床气化过程未来的研究重点进行了展望.     

用激光衍射法研究电解气泡的大小及其分布

应用激光衍射法研究了电化学反应中析出的氢和氧气泡的大小及其分布.发现在一定电解条件下气泡的大小在较宽的范围内变化,并给出了其统计规律.电流密度和电极材料对于较少发生聚并的氢气泡的大小及分布影响较小,对发生聚并的氧气泡影响较大.当电解液由碱性变为酸性时,氢气泡显著增大,而氧气泡急剧减小,二者的分布规律也发生根本变化.     

毛细管区带电泳中场增强进样柱内富集的非线性特征

直接柱头场效应进样是一种毛细管区带电泳柱内富集,其进样过程中样品在柱内的分布可分为两部分,即在运行缓冲溶液中的堆积区段和由电渗流引入的样品溶液区段.通过对溶质输运行为的研究表明:两区段长度与进样时间之间并非简单的线性关系,因此进样量与进样时间的关系也非线性,且与溶质淌度有关;进样量的增加并不能导致富集倍数的同步增加,由于层流的作用使得场效应进样柱内富集效果降低.为了在保持柱效基本不变情况下得到好的富集效果,除需使溶质在运行缓冲溶液和样品溶液中的电导率比极大外,进样时间也应与之匹配.     

色谱动力学过程的分析

]本文对样品在色谱柱中经历的进样、上柱、柱内、柱末端及柱外这一系列动力学过程中谱带的宽度所发生的变化及相互间的关系进行了分析。     

电中性溶质在反相毛细管电色谱柱上峰展宽的研究

根据溶质在色谱柱中迁移的基本特征及柱分离过程弛豫理论的一般输运方程,在平衡色谱和不单独考虑逆向流的简化情况下,得到了能够说明多种因素对半峰宽影响的流出曲线的二阶中心矩表达式。通过反相毛细管电色谱实验,讨论了电压、柱长及保留因子等因素与峰展宽之间的关系,也探讨了溶质在色谱柱内峰展宽的规律。结果表明:半峰宽随柱长的增加和保留因子的增大而线性增加,随电压的增加而呈非线性减小。     

Regeneration of tetrabutylammonium ion-pairing reagent distribution in a gradient elution of reversed phase ion-pair chromatography

The regeneration of ion-pairing reagent distribution on liquid chromatography columns after gradient elution has been well recognized as the cause for long column equilibration time, a major drawback associated with gradient elution reverse phase ion-pair chromatography. To date, the majority of studies have focused on optimizing the separation conditions to shorten the equilibration time. There is limited understanding of the ion-pairing reagent distribution process between the mobile phase and stationary phase in the course of gradient elution, and subsequent column re-equilibration. The focus of this work is to gain a better understanding of this process. An ion-pair chromatographic system, equipped with a YMC ODS C(18) column and a mobile phase containing tetrabutylammonium (TBA) hydroxide as the ion-pairing reagent, was used in the study. The TBA distribution profile was established by measuring its concentration in the eluent fractions collected during the gradient cycle using different column equilibration times with an ion chromatographic method. Furthermore, the analyte retention time was evaluated as the function of the column equilibration time and TBA concentration in the mobile phase. The column equilibration and its impact on the method robustness will also be discussed.     

Development of dual gradient column in liquid chromatography

The dual gradient column, in which both the chemical property of the stationary phase and the flow velocity in the mobile phase are heterogeneous longitudinally along the column, is developed to obtain the mobile phase gradient-like elution in an isocratic condition. Here, the step-wise dual gradient columns were prepared by connecting an inlet column (I.D. 50 microm, packed with ODS) serially to an outlet column (I.D. 100-200 microm, packed with the mixture of ODS and C1 [9:1]). The retention behavior of alkylbenzenes was able to be controlled in the dual gradient column depending on the variation in the flow velocity. Moreover, the change in retention behavior induced by the flow velocity variation for the dual gradient columns was quite different from that by the variation in organic modifier content of the mobile phase in isocratic elution for a single gradient column and can induce the similar effect with an ordinary gradient elution in a mobile phase composition.     

Reversed-phase high-performance liquid chromatographic separation of mono- and divinyl chlorophyll forms using pyridine-containing mobile phases and a polymeric octadecylsilica column

Summary The separation of chlorophyll forms was studied employing a wide bore polymeric octadecylsilica column and pyridine containing mobile phases, giving consideration to considering the influence of mobile phase composition and column temperature on the resolution of monovinyl forms from their divinyl analogues. A method involving gradient elution and operating at 15°C is proposed for the separation of several polar and non-polar mono- and divinyl chlorophylls from etiolated tissues of higher plants and from marine phytoplankton. The advantages of pyridine as a mobile phase additive in the reversed-phase liquid chromatography of chlorophylls are discussed.     

Theoretical and experimental comparison of mobile phase consumption between ultra-high-performance liquid chromatography and high performance liquid chromatography

Ultra performance liquid chromatography (UPLC) using small particles and very high pressure has demonstrated higher resolution and speed compared with conventional HPLC. An additional benefit of UPLC is the significantly reduced consumption of mobile phase. This report discusses how column length, particle size, inner column diameter, extra column void volume, and capacity factor contribute to the reduction of mobile phase consumption in UPLC compared with HPLC. In addition, theoretical and experimental comparison of mobile phase consumption was made between isocratic HPLC and UPLC as well as between gradient HPLC and UPLC. Both theoretical and experimental results indicate that UPLC typically saves at least 80% of mobile phase in isocratic and gradient conditions when compared with HPLC.     

梯度液相色谱中梯度曲线变形对色谱峰宽的影响

在梯度液相色谱中,溶剂混合以及轴向扩散等因素会使梯度曲线发生变形,而这在阶梯梯度以及高斜率的线性梯度中表现得尤为明显。本文探讨了这种梯度曲线变形对色谱峰宽的影响。首先以C18色谱柱为固定相,甲醇-水为流动相,联苯和苯乙酮为样品,测得不同线性梯度和阶梯梯度条件下的色谱峰。然后以205 nm为检测波长,记录相应条件下未接色谱柱时甲醇的响应值,得到柱入口处的梯度曲线。接着根据所设定的梯度条件以及柱入口处测得的梯度曲线,分别计算相应情形中色谱峰宽的理论值,将其与实验值进行了比较。研究结果表明,梯度曲线的变形会对色谱峰宽产生影响。当将这种影响考虑在内后,理论值与实验值更为吻合。     

Can the theory of gradient liquid chromatography be useful in solving practical problems?

Advances in the theory of gradient liquid chromatography and their practical impacts are reviewed. Theoretical models describing retention in reversed-phase, normal-phase and ion-exchange modes are compared. Main attention is focused on practically useful models described by two- or three-parameter equations fitting the experimental data in the range of mobile phase composition utilized for sample migration during gradient elution. The applications of theory for gradient method development, optimization and transfer are addressed. The origins and possibilities for overcoming possible pitfalls are discussed, including the effects of the instrumental dwell volume, uptake of mobile phase components on the column and size of the sample molecules. Special attention is focused on gradient separations of large molecules.     

Column radial homogeneity in high-performance liquid chromatography

The radial distribution of analyte molecules within an elution band in HPLC was determined by local, on-column, fluorescence detection at the column outlet. Several optical fiber assemblies were implanted in the exit frit at different points over the column cross-section and the fluorescence of a laser-dye analyte was measured. The individual elements of a diode array were used as independent detectors. The distribution of the mobile phase velocity across the column was measured for a number of standard size analytical HPLC columns of different efficiencies, operated at different mobile phase linear velocities. The dependence of the column efficiency on these profiles is discussed.     

The principle of optimization of binary mobile phase composition of multi-step linear gradient elution

The basic principle of optimal method called “moving overlapping resolution mapping method” to select the optimal binary mobile phase composition of multi-step linear gradient liquid chromatography is discussed with simultaneously considering effects of position of solute inside the column and mobile phase composition on peak resolution and retention value, then a BASIC program based on this principle is developed in IBM-PC computer. The validities of both principle of optimization and BASIC program are confirmed by separation of samples containing bile acids and PAHs in RP-HPLC.     

Separation of ferrichromes and other hydroxamate siderophores of fungal origin by reversed-phase chromatography

Iron(III) chelates of nineteen trihydroxamate siderophores of fungal origin, including ferrichromes, coprogen and triacetylfusarinine C, were separated on a preparative scale with a reversed-phase column using the octadecyl silica gels LRP-1 or LRP-2 as the stationary phase and a water-methanol gradient as the mobile phase. Using this system in combination with silica gel column chromatography, most siderophores can be obtained in pure form. Factors affecting the mobility of these compounds in the reversed-phase system are discussed.     

反相高效液相色谱中流动相线性梯度洗脱条件下溶质保留时间预测的新方法

 在计算溶质的梯度保留时间时 ,根据流动相在色谱柱内的分布规律 ,对溶质在色谱柱内的迁移距离和流动相梯度同时进行校正 ,从而建立了一种预测溶质线性梯度洗脱条件下保留时间的新方法。该方法在不同的仪器系统中 ,对于弱保留和强保留溶质在不同线性梯度洗脱条件下保留时间的预测 ,都具有良好的准确度。以 15种氨基酸和 8种苯的同系物为例 ,该方法对于弱保留溶质保留时间的预测 ,相对平均误差分别为 3 70 %和 4 90 % ,远小于文献方法得到的结果 (2 3 6 1%和 31 16 % ) ;对于强保留溶质保留时间的预测 ,相对平均误差分别为 0 2 1%和6 0 1% ,略小于文献 。