Effect of Alkyl Chain Length of Bonded Silica Phases on Separation,Resolution and Efficiency in High Performance Liquid Chromatography

Abstract

A comparative study of alkyl bonded phases was carried out under optimum solvent conditions for each phase. Three columns, RP-2, RP-8 and RP-18, were tested for their efficiency and resolving power using three groups of compounds in three binary organic-water mobile phases. The organic solvents were acetonitrile, methanol and tetrahydrofuran which are widely used as solvent modifiers.

The results indicate that each of the three factors, i.e. solvent, solute and bonded alkyl chain length, play an important role, with the solvent being the most significant. When tetrahydrofuran-water was used as the mobile phase, the ratio of THF/H₂O did not vary by much when an RP-2, RP-8 or RP-18 column was used to separate naphthalene from biphenyl, dimethylphthalate from diethylphthalate or anthraquinone from methyl, anthraquinone and ethyl anthraquinone. When acetonitrile-water and methanol-water were used the ratio of organic modefier to water changed so as to accomodate the hydrophobic properties of the columns. The efficiency of the columns, expressed as theoretical plates per meter (TPM) was highest when acetonitrile-water was used as the mobile phase. Although there were variations in TPM and resolution from column to column, the three columns gave good separation of the components of the three groups of compounds.     

Direct Resolution of Enantiomers in Column Liquid Chromatography

Abstract

Important progress has been performed during the ten past years, in the direct resolution (without derivatization) of enantiomers by column liquid chromatography. Generally chiral packings proceeding from natural or synthetic optically active polymers are used. Complete resolutions of hole families of chiral solutes is obtained in systems involving a steric locking interaction (charge transfer between aromatic substituents, crown ether cavity, crowded complexes with metal ions). For analytical purposes an other proraising way is the use of a classical packing and a chiral mobile phase.     

Quantitative High - Resolution Gas Chromatography and High - Resolution Gas Chromatography/Mass Spectrometry Analyses of Carbonaceous Fine Aerosol Particles

Abstract

Methods have been developed for the quantification of low-microgram levels of the extractable organic matter contained in the atmospheric fine aerosol fraction. Extract quantification is accomplished by computer-assisted high-resolution gas chromatography (HRGC) used in conjunction with a procedural recovery mixture containing perdeuterated compounds of differing polarity and molecular weight. Recovery data for these species indicate that relative volatility rather than functional group classification is the primary factor affecting overall recovery. Routine quality control analysis is performed on a per-sample basis by high-resolution gas chromatography/mass spectrometry (HRGC/MS) for confirmation of the standard components and for identification of procedural contaminants. By the way of illustration, fine aerosol samples have been analyzed from Anaheim. California. The absolute solvent extract yields range from 49 to 346μg of organic carbon, and demonstrate a seasonal variation with winter maximum and summer minimum concentrations.     

高分辨气相色谱/高分辨质谱联用测定大气降尘中的二噁英

样品采取索氏抽提,抽提液依次经多段混合硅胶柱、氧化铝柱和硅胶柱净化后,采用同位素稀释法和高分辨气相色谱/高分辨质谱联用仪(HRGC/HRMS)对其中的17个2,3,7,8-氯取代二噁英(PCDD/Fs)同系物进行了测定。研究结果表明,用本法4次分析二噁英标准溶液,其结果的RSD<7.1%;回收率可达62%~103%;标准参考样品的分析结果与标准值基本吻合,3次实验结果的RSD≤15%;仪器检出限为2,3,7,8-TCDF 0.1 pg,2,3,7,8-TCDD 0.2 pg,OCDD 0.8 pg;测定某降尘样品中二噁英,计算得降尘通量为14.02 pgTEQ m-2day-1。     

手性有机磷化合物液相拆分的研究进展

 综述了近年来手性有机磷化合物液相拆分的研究进展。对间接拆分和直接拆分法,特别是各类手性固定相法在拆分有机磷化合物中的应用作了介绍,探讨了相应的拆分机理。85篇。     

An Analysis of Imperfect Resolution in the Chromatography of Particle Suspensions

Abstract

Here-in is reported a general method of correction for imperfect resolution in the chromatography of particle suspensions. It overcomes most of the limitations of previously reported methods. A non-linear particle diameter - retention volume calibration curve and a generalised spreading function are considered. Moment equations are developed for two types of general detectors; the first type includes a refractive index detector and a turbidity detector with Rayleigh scattering while the second type includes a tubidity detector with Mie scattering. The moment equations were applied to the analysis of chromatograms of narrow Dow polystyrene latices measured by size exclusion chromatography.     

The Efficiency of Substance Separation in Countercurrent Liquid Chromatography

The effect of hydrodynamic parameters and the specific features of instrument design on the efficiency of substance separation in countercurrent liquid chromatography (CCC) was studied using a constant retention factor of the stationary phase in the column. The study was conducted with the separation of benzyl alcohol and p-cresol in a two-phase liquid system heptane–ethyl acetate–methanol–water (1.4 : 0.6 : 1 : 1) in as an example. It was shown that the peak resolution is improved with an increase in the rotational speed of the column and a decrease in the flow rate of the mobile phase. The best peak separation was attained using columns for which the ratio of the column rotation radius to the radius of column revolution was 0.615. It was shown that countercurrent chromatography allows the separation of substances with low partition constants (K < 1) in dilute solutions. The volume of the test sample may be up to 15% of the total volume of the chromatography column.     

手性配位体交换流动相添加剂法拆分对映体

综述了手性配合基交换色谱法通常采用三种手性相系统中的流动相添加剂方法。主要内容有：（Ａ）手性配合基交换机制,给出了描述对映体对在色谱系统中的保留时间和分离选择性的公式,包括手性选择剂在固定相和流动相中的各种不同情况。公式表明整个色谱往系统的对映体选择性不同于溶液中所存在的选择剂与被选择物作用的情况;（Ｂ）影响配合交换的参数,讨论了金属离子、金属离子／配位体比率、金属离子络合物浓度、固定相、流动相ｐＨ、洗脱顺序、有机调节剂、离子对试剂、流动相离子强度、温度、立体选择性和手性交互识别;（Ｃ）应用。     

高效液相色谱法对二氢吡喃酮衍生物的手性拆分

介绍了利用手性chiralcel OD和chiralpak AD柱在高效液相色谱上对一系列二氢吡喃酮衍生物进行手性拆分，获得了良好的分离结果，考察了部分对映体在这两种柱上的色谱行为。实验表明手性化合物与手性柱之间存在着化学作用与空间作用，两者的共同作用决定了分离结果。     

用气液分配色谱对外消旋2-辛醇的析解

我们曾报导^[1]用光学活性试剂α-乙酰氧基-L-丙酰氯与外消旋2-丁醇反应,生成相应的一对非对映异构体酯,经气液分配色谱作定量测定,达到快速、微量分析其旋光异构体含量的目的。     

高效液相色谱法拆分雷喏嗪

用高效液相色谱法(HPLC)在正相条件下,用自制的涂敷直链淀粉-三(3,5-基苯基氨基甲酸酯)(ADMPC)手性固定相直接拆分了高效低毒的抗心绞痛药物雷喏嗪外消旋体(Ranolazine),并考察了二元及三元流动相体系对样品分离的影响,结果表明,三元流动相中的拆分结果远远好于二元流动相,流动相中不同种类醇改性剂及含量对样品保留时间和立体选择性有不同程度的影响．     

液相色谱手性拆分机理的热力学方法研究

手性识别是分子识别的一个重要组成部分。液相色谱手性拆分机理研究有助于色谱条件的优化和新型手性固定相的设计,也有助于理解手性识别机制。本文就线性色谱与非线性色谱条件下手性拆分过程对应热力学参数的推求方法进行了评述,阐述了相关热力学参数的涵义及其在色谱保留及手性拆分机理探讨中的应用,并展望了该领域的研究前景。     

液相色谱手性拆分机理的热力学方法研究

手性识别是分子识别的一个重要组成部分。液相色谱手性拆分机理研究有助于色谱条件的优化和新型手性固定相的设计,也有助于理解手性识别机制。本文就线性色谱与非线性色谱条件下手性拆分过程对应热力学参数的推求方法进行了评述,阐述了相关热力学参数的涵义及其在色谱保留及手性拆分机理探讨中的应用,并展望了该领域的研究前景。     

脲型手性固定相高效液相色谱拆分苯基琥珀酸对映体

苯基琥珀酸(PSA)是药物原料N 甲基 α 苯基琥珀酰亚胺(phensuximide)的重要中间体。(S) ( ) PSA是一种很好的扑尔敏药物手性拆分剂,并可作为手性选择子合成液相色谱手性固定相[1]。外消旋的PSA通常采用光活性的番木鳖碱或(-) 脯氨酸化学衍生结晶拆分[2,3]。PSA对映体的高效液相色谱(HPLC)拆分未见文献报道。1　实验部分　　仪器　美国TSP公司HPLC仪:3500 3200型高压梯度泵,UV2000型双波长紫外吸收检测器,Rheodyne7725i进样阀,PC1000色谱工作站。PE341型旋光仪。　　试剂　正己烷、1,2 二氯乙烷、乙醇、三氟乙酸,均为国产分…     

吡氟禾草灵的高效液相色谱法拆分与测定

在流动相为正庚烷-异丙醇-三氟乙酸(99.3:0.5:0.2,体积比),流速为0.6 mL·min-1,检测波长为273 am,柱温为10℃的分析条件下,利用手性色谱柱Nucleosil chiral-2实现了吡氟禾草灵对映体的手性分离,在优化的色谱分离条件下,R-型异构体的峰面积与其对应浓度之间保持线性关系,其对应的线性回归方程为A=(236.30ρ 1.94)×100,其相关系数为0.9991.据此可定量测定R型异构体.     

Centrifugal Partition Chromatography. II. Selectivity Efficiency

Abstract

Centrifugal Partition Chromatography (CPC) is a technique that uses two immiscible liquids. One liquid is used as a stationary phase, the second one as the mobile phase. Using the liquid systems methanol-hexane and octanol-water, the selectivity and efficiency of CPC apparatus were tested. It is shown that CPC can be used to determine partition coefficients or to purify compounds. The selectivity can be changed the same way as in liquid chromatography. The efficiency study has shown that the plate count presents a minimum value at a particular flow rate. By plotting the number of channels required to obtain one theoretical plate versus the flow rate, it is possible to obtain a “van Deemter-type” plot. Interestingly, these plots show maxima for CPC. These results are opposite to those found for liquid or gas chromatography which have minima. A flow change, from laminar to nonlaminar is thought to explain these results. Reynolds numbers were determined for all solvent systems. Efficiency in CPC was also found to be solute dependent: the larger the partition coefficient, the lower the efficiency.     

高分辨气相色谱-高分辨质谱测定活性污泥中的多溴联苯醚

建立了利用高分辨气相色谱-高分辨质谱定量测定多溴联苯醚(PBDEs)的方法,参与了测定PBDEs的国际比对实验,实验结果表明该法是可行的。对不同地区（北京、山东临沂、上海）的3个污水处理厂的活性污泥进行了索氏提取、多层复合硅胶柱分离,然后用所建立的方法测定了19种多溴联苯醚单体的含量。结果表明,北京某污水处理厂的活性污泥中PBDEs的总量高于其他两者。     

β-环糊精固载硅胶薄层色谱法拆分盐酸克伦特罗对映体

以羧甲基纤维素钠为交联剂,将β-环糊精固载在硅胶GF254表面上,并用其制备薄层色谱板。使用该薄层板拆分了盐酸克伦特罗对映异构体。考察了薄层拆分中展开剂的影响,发现展开剂中醇的种类和比例对拆分效果有较大的影响。分别考察了10种醇与乙腈混合溶剂作展开剂对拆分的影响,结果显示,只有正丁醇-乙腈、仲丁醇-乙腈、叔丁醇-乙腈混合溶剂作展开剂可拆分盐酸克伦特罗对映体。薄层色谱法拆分盐酸克伦特罗对映体的条件为：以1.00 g β-环糊精固载在15.00 g硅胶GF254表面上,并用其制备薄层板,以乙腈-仲丁醇(体积比为20∶80)混合溶剂作展开剂,于室温下展开。在此条件下,盐酸克伦特罗对映体单体在薄层色谱板上的比移值Rf分别为0.34和0.72,分离度Rs为4.09,实现了基线分离,而且样品在薄层色谱板上的斑点大小一致,拆分效果最好。     

气相色谱/高分辨双聚焦磁式质谱联用仪定量检测市售猪肉中二噁英

采用高分辨气相色谱 高分辨双聚焦磁式质谱联用仪 (HRGC HRMS)定量检测了市售猪肉中 1 7个 4～ 8个氯原子取代的二英和呋喃 (PCDDs Fs)。样品中的二英经过索式抽提、浓缩、碳柱富集、色谱柱纯化和分离 ,以HRGC HRMS 多离子检测方式对样品中的PCDDs Fs进行定性分析 ,同位素稀释技术定量 ,该方法定量可精确到pg g水平。结果表明 :该方法的检出限TCDF和TCDD均为 0 0 1pg g。同位素标准物的回收率分布于 68.6%～ 92 .4 %之间。样品中 1 7个同系物异构体以OCDD的含量为最高 ,为 0 .65 3pg g,OCDF为0 1 2 6pg g,其它均未检出。采用WHO的毒性等量因子 (TEF)计算样品的PCDDs Fs浓度为 0 .0 0 0 1pgTEQ g。该方法定性、定量准确 ,为目前国际上权威认可的二英定量检测方法